CONTENTS
UNIT VI
REPRODUCTION
Chapter 1 : Reproduction in Organisms
Chapter 2 : Sexual Reproduction in Flowering Plants
Chapter 3 : Human Reproduction
Chapter 4 : Reproductive Health
UNIT VII
GENETICS AND EVOLUTION
Chapter 5 : Principles of Inheritance and Variation
Chapter 6 : Molecular Basis of Inheritance
Chapter 7 : Evolution
UNIT VIII
BIOLOGY IN HUMAN WELFARE
Chapter 8 : Human Health and Disease
Chapter 9 : Strategies for Enhancement in Food Production
Chapter 10 : Microbes in Human Welfare
UNIT IX
BIOTECHNOLOGY
Chapter 11 : Biotechnology: Principles and Processes
Chapter 12 : Biotechnology and its Applications
UNIT X
ECOLOGY
Chapter 13 : Organisms and Populations
Chapter 14 : Ecosystem
Chapter 15 : Biodiversity and Conservation
Chapter 16 : Environmental Issues
UNIT VI
REPRODUCTION
CHAPTER – 1
REPRODUCTION IN ORGANISMS
LIFE SPAN- The period from birth to the natural death of an organism represents its life span.
REPRODUCTION- It is defined as a biological process in which an organism give rise to young ones (offspring) similar to itself. It may be also defined as the process of self replication of organism either by the utilization of somatic cell or germ cell. Based on whether there is the utilization of somatic cell or germ cell, reproduction is of two types:-
REPRODUCTION
ASEXUAL REPRODUCTION SEXUAL REPRODUCTION
ASEXUAL REPRODUCTION
In Asexual reproduction, offspring is produced without the involvement of gamete formation. In this method the somatic cell which forms the vegetative body divides into new vegetative body which has the capacity to form the complete organisms which are genetically and morphologically similar to their parent known as clone.
A single individual is capable of producing offspring.
Higher animals do not naturally reproduce asexually. It is common in single celled organism, animals and plants with simple organization.
Asexual reproduction takes place by several methods:-
i. FISSION
a) BINARY FISSION: - It is a method of reproduction, where a cell divides into two halves i.e. two daughter cells by mitosis an each rapidly grows into an adult. Example- Amoeba, paramecium, euglena.
b) MULTIPLE FISSION:- During this process firstly the single cell undergoes the process of encystment. After that the protoplasm divides into a number of small unit after a series continuous mitotic cell division. Each unit resembles with an unicellular cell which burst out from the cyst and each one develop into a new organism.
Example - Malarial parasite (sporozoa), plasmodium.
ii. BUDDING: - It is a process in which a new individual is produced as an out growth (bud) of a parent and is later released as a self supporting, identical copy of the parent.
Example- Hydra.
iii. SPORULATION: - A spore is a small reproductive body which is microscopic and unicellular containing a small amount of cytoplasm and a nucleus. The groups of algae and fungi reproduce by the formation of asexual spores as a result of mitotic cell division. The spores may be zoospores, conidia or simple spores.
iv. FRAGMENTATION: - It is the breaking of an organism into two or more parts each of which grows to form a new individual. Example- Spirogyra.
v. VEGETATIVE PROPAGATION: - In plants the asexual mode of reproduction is referred to as vegetative propagation. The vegetative parts which are responsible for vegetative propagation are known as vegetative propagules and they are- rhizome, runner, bulb, sucker, tuber, offset and leaf.
SEXUAL REPRODUCTION
The process of reproduction in which there is the involvement of germ cell in the form of gametes which fuses to form the zygote and the zygote is the first cell of next generation is known as sexual reproduction. Before the formation of gametes the organism undergoes the process of growth and this period of growth is known as juvenile phase and vegetative phase in plants.
Sexual reproduction takes place in dioecious as well as in monoecious animals.
Monoecious animals are those which possess male and female reproductive organs in the same individual. Also called bisexual or hermaphrodite. Example- Pheretima.
EVENTS IN SEXUAL REPRODUCTION: - The fusion of gamete is known as sexual reproduction. As fertilization which is completed in three main stages-
i.Pre fertilization
ii.Fertilization
iii.Post fertilization
PRE FERTILISATION: - This is the stage of gamete formation and its transfer. The process of gamete formation is known as gametogenesis and the transfer of gamete is known as pollination in case of plant.
TYPES OF GAMETES: - As per the shape and size and the role of gamete during fertilization, gametes are of following types:-
a)ISOGAMETES:- The gametes of unicellular organisms are similar with each other known as isogametes or homogametes. Example- Algae
b)ANISOGAMETES:- When the gametes are dissimilar in shape and size known as heterogametes. In such organisms the small gamete is the male gamete known as antherozoid or sperm and the larger gamete is the female gamete known as egg or ovum.
SEXUALITY IN ORGANISM
i. MONOECIOUS: - If the organism bears or develops both the male and female reproductive structure in the same body known as monoecious, homothallic or bisexual organism.
ii. DIOECIOUS: - If the male and female reproductive parts develop in different body known as dioecious, heterothallic or unisexual organism. The unisexual male plants are known as staminate plants and the female plants are known as pistillate plants.
In animals most of the species of unisexual and few are hermaphrodite bearing both reproductive organs.
CELL DIVISION DURING GAMETE FORMATION:-
During the process of asexual reproduction and vegetative propagation there is a process of mitotic cell division for reproduction. All the cells remain diploid during the process of mitosis.
In sexual reproduction specialized cells known as gamete mother cells or meiocytes which are diploid in nature undergoes the process meiosis to form the haploid gametes.
In lower organisms like few algae and fungi possess the haploid body automatically produce the haploid gametes after the process mitosis. Gametes fuse to form the diploid zygote, zygote undergoes meiosis forms haploid body.
GAMETE TRANSFER: - In plants male gametes are present inside the pollen grains which need to be transferred to the stigma for the process of fertilization by the mechanism pollination. The agents like insects, wind, water responsible for pollination are known as pollinating agents. The female gamete is known as egg which is present inside the embryo sac.
FERTILISATION: - The process of fusion of male and female gamete results in the formation of diploid zygote by the process known as fertilization or syngamy. The process of fusion if taking place inside the body part of the organism, it is known as internal fertilization.
Example-Higher animals, angiosperms etc.
PARTHENOGENESIS: - Sometimes the female gametes may develop into a new organism without fertilization and the process is known as parthenogenesis. Seedless fruits are developed after the process of parthenogenesis.
EXTERNAL FERTILISATION: - In most aquatic organism, fertilization occurs in aquatic medium (water), i.e. outside the body of the organism. This type of gametic fusion is called external fertilization. Example - amphibians.
POST-FERTILIZATION EVENTS: - Events in sexual reproduction after the formation of zygote are called post-fertilization events.
THE ZYGOTE: - Zygote is diploid in nature which undergoes mitotic cell division to form the diploid organism. Before forming the complete organism, embryo forms from the zygote by the process of embryogenesis.
EMBRYOGENESIS: - This refers to the process of development of embryo from the zygote. During embryogenesis, zygote undergoes cell division (mitosis) and cell differentiation. Animals are categorized into oviparous and viviparous based on whether the development of the zygote takes place outside the body of the female parent or inside.
OVIPAROUS- The animals which lay eggs inside which the fertilized egg is present are known as oviparous animals. Example- Birds, reptiles.
VIVIPAROUS- The animals which give birth to young ones and the development of fertilized egg is inside the mother’s body are known as viviparous animals. Example – Mammals.
Important diagrams from NCERT Text book:-
Page no.- 5, Figure- 1.2 (a), (b)
Page no.- 14, figure- 1.7 (a)
RELATED QUESTIONS
Very short answer questions (1 mark each)
1.What is binary fission? Give two examples.
2. Name the five units of vegetative propagation.
3.Name main events of sexual reproduction.
4. Define embryogenesis.
5.Why is the offspring formed by asexual reproduction referred to as clone?
Short answer type question (2 mark each)
1.Write short note on pollination.
2. Why offspring of oviparous animals are at a greater risk?
3. Differentiate between gametogenesis and embryogenesis.
4. How nodes are important in case of vegetative reproduction of potato and sugarcane? What are these vegetative parts known?
5. Why vegetative propagation is also considered as a type of asexual reproduction?
Short answer type question (3 mark)
1.Differentiate between homo gametes and heterogametes. Give suitable examples .
2.Define
(a)Juvenile phase
(b)Reproductive phase
(c)Senescent phase.
3.Define external fertilization. Mention its disadvantages.
4.Describe the post fertilization changes in a flower.
5.Write a note on micro propagation.
Long answer question (5 marks each)
1.How would you define life span of an organism? Give life spans of ten organisms, you are familiar with.
2. Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
3.Give the types of vegetative propagation in:
(i)Potato
(ii)Bryophyllum
(iii)Ginger
4.What are dioecious and monoecious plants? Give botanical names of three plants bearing unisexual flowers.
5.Write a short note on asexual reproduction.
CHAPTER-2
SEXUAL REPRODUCTION IN FLOWERING PLANTS
A typical angiospermic plant comprising of four whorls. These are,
1)Calyx
2)Corolla;
3)Androecium
4)gynoecium
Out of which androecium and gynoecium is meant for sexual reproduction.
STAMEN, MICROSPORANGIUM AND POLLEN GRAIN
The male unit of angiospermic flowers is known as androecium which units are stamen and the flower which bears only the stamen is known as staminate flower. Each stamen is divided into two parts,
-The filament
-Anther
A typical anther is bilobed with each lobe having two theca i.e., they are dithecous. The anther is a four-sided structure consisting of four microsporangia located at the corners, two in each lobe. The microsporangia develop further and become pollen sacs.
STRUCTURE OF MICROSPORANGIUM
Microsporangium is generally surrounded by four wall layers. These are
-Epidermis
-Endothecium
-Middle layer
-Tapetum
The outer three layers perform the function of protection and help in dehiscence of anther to release pollen. The innermost layer is tapetum. It nourishes the developing pollen grains.
When the anther is young, a group of compactly arranged homogenous cells called the sporogenous tissue occupies the center of each microsporangium.
MICROSPOROGENESIS
The process in which the microspore mother cell forms the microspore or pollen grain is known as microsporogenesis.
The microspore as they are formed, are arranged in a cluster of four cells-the microspore tetrad.
POLLEN GRAIN
The pollen grain represents the male gametophyte. It has a prominent two-layered wall. The hard outer layer called the exine, which is made up of sporopollenine. Pollen grain exine has prominent apertures called germ pore where sporopollenine is absent. The inner wall of pollen grain is known as intine. It is made up of cellulose and pectin.
When the pollen grain is mature it contains two cells
1)Vegetative cell
2)Generative cell
MEGASPOROGENESIS
The process of formation of megaspore from megaspore-mother cell which finally form the egg cell is known as megasporogenesis. This takes place inside the gynoecium which unit is pistil.
THE MEGASPORANGIUM (OVULE)
The ovule is a small structure attached to the placenta by means of a stalk called funicle. The body of the ovule fuses with funicle in the region called hilum. Each ovule has one or two protective envelopes called integuments. Integuments encircle the ovule except at the tip where a small opening called the micropyle is organized. Opposite the micropylar end, is the chalaza, representing the basal part of the ovule.
Enclosed within the integument is a mass of cells called the nucellus. Located in the nucellus is the embryo sac or female gametophyte. An ovule generally has a single embryo sac formed from a megaspore through reduction division.
FEMALE GAMETOPHYTE
In a majority of flowering plants, one of the megaspore is functional while the other degenerate, only the functional megaspore develops into the female gametophyte. This method of embryo sac formation form a single megaspore is termed monosporic development.
The nucleus of the functional megaspore divides mitotically to form two nuclei which move to opposite pole, forming the 2-nucleate embryo sac. Two more sequential divisions results in the formation of the 4-nucleate and layer the 8-nucleate stages of the embryo sac. After 8-nucleate stage, cell walls are laid down leading to the organization of the typical female gametophyte.
There is a characteristic distribution of the cells within the embryo sac. Three cells are grouped together at the micropylar end and constitute the egg apparatus. The egg apparatus, in turn consist of two synergids and one egg cell.
Three cells are at the chalazal end and are called the antipodal. The large central cell, as mentioned earlier, has two polar nuclei. Thus; a typical angiosperm embryo sac at maturity though 8-nucleate is 7-celled.
POLLINATION
After the maturation of pollen grain and embryo cell before fertilization transfer of pollen grain is known as pollination. Agents are required for the process of pollination is mainly biotic or abiotic.
TYPES OF POLLINATION
It is mainly three types
1. Autogamy:
It is transfer of pollen grain from the anther to stigma of the same flower known as autogamy .It takes place in two various modes in few different types of flower-
(a).Chasmogamous flower in which the anther and stigma are open.
Eg: Oxalis
(b).Cleistogamous flower in which all the anther and stigma are closed to each other.Ex: Ficus
2. Geitonogamy:
If the transfer of pollen grain from anther to stigma of different flowers of the same plant, the pollination is known as Geitonogamy
3. Xenogamy:
Transfer of pollen grain from anther to stigma of different flower of different plant is called Xenogamy
AGENTS OF POLLINATION
The abiotic agents are –wind and water and biotic agents are-various animals. Some examples of various agents are
(a) WIND: Brassica
(b) WATER: Vallisneria
(c) ANIMAL: Grass
(d) INSECT: Family Solanacea
OUTBREEDING DEVICES:
Cross pollination is supposed to be the advanced than self pollination. The natural development of flower to adopt cross pollination is termed as outbreeding device .This may be carried out by artificial method of breeding also.
ARTIFICIAL HYBRIDIZATION:
The process of desired pollination among the selected pollen grain and stigma is known as artificial hybridization. It includes two steps:
(a)EMASCULATION:- The removal of anthers before maturation
in bisexual plants.
(b)BAGGING:- The covering of stigma to check the contamination
of unwanted pollen grain by polythene packets is known as bagging.
DOUBLE FERTILISATION:-
Angiospermic fertilization is known as double fertilization as two haploid nucleus are simultaneously fertilized during fertilization. Two male gametes are discharge from the pollen tube into the embryo cell. One male gamete fused with the x- cell and form the diploid zygote and the process of fusion is known as syngamy.
The second male gamete fuses with the two centrally polar nuclei (N) and form a triploid primary endosperm nucleus which later on develop to form the endosperm. The second fusion is known as triple fusion.
ENDOSPERM:-
It is the product of triple fusion which earlier appears as primary nucleus suddenly after the fusion, the primary endosperm nucleus divides and redivides and form a mass of endosperm tissue in the early stage there is only nuclear division and the endosperm is knows as free nuclear endosperm.
Ex:- coconut milk.
Later on there is the formation of cell wall to form the mature endosperm.
Ex:- white edible part of coconut.
EMBRYO:-
Zygote is present at the micropylar and which further divide to form the embryo. The development of embryo is known as embryogeny.
SEED
After the process of fertilization the ovule modified into seed which germinate to form the new plants. Seeds are of two types:-
a)Non- albuminous:- In which the endosperm is completely consumed during the embroyonal development.
Ex:- pea
b)Albuminous:- The seed in which the endosperm is not completely consumed during the embroynal development.
Ex:- wheat
DORMANCY:-
The stage of resting in which the physiological activity of seed is inactive is known as dormancy. The conditions required for dormancy are less water content, high temperature and moisture free environment.
PERICARP:-
The wall of the ovary develops into the wall of fruit called pericarp.
FRUIT:-
The mature ovary is known as fruit. The wall of the ovary gets converted into the wall of the fruit.
FALSE FRUIT:-
The fruit in which the thalamus also contributes is known as false fruit.
Ex:-apple.
TRUE FRUIT:-
The fruits which only develop from the ovary are called as true fruit. Ex:-mango.
PARTHENOCARPIC FRUIT:-
The fruit developed without fertilization are known as parthenocarpic fruit.
Ex:-banana.
APOMIXIS:-
The artificial method of production of seed without fertilization is known as apomixes.
Ex:-Citrus
POLYEMBRYONY:-
Presence of more than one embryo per seed is known as polyembryony.
IMPORTANT ABBREVIATIONS:-
1)PMC:- Pollen Mother Cell.
2)MMC:- Megaspore Mother Cell.
3)PEN:- Primary Endosperm Nucleus.
4)PEC:- Primary Endosperm Cell.
IMPORTANT DIAGRAMS:-
Fig. no:-2.2(a), page no:-21(NCERT)
Fig. no:-2.3(b), page no:-22( ,, )
Fig. no:-2.7(d), page no:-25( ,, )
Fig. no:-2.8(c), page no:-26( ,, )
Fig. no:-2.13(a) page no:-34 ( ,, )
QUESTIONS
Question carries 1 marks
1)Give one difference between epicarp and pericarp
2)Why apple is called a false fruit?
3)What is meant by babbling?
4)What is triple fusion?
5)What is apomixis?
Question carries 2 marks
1)What is meant by monosporic development of female gametophyte?
2)What do mean by pollination?
3)What do you mean by outbreeding devices?
4)What do you mean by megasporogenesis?
5)What do you mean by microsporogenesis?
Question carries 3 marks
1)Draw and label a diagram of a ovule.
2),, ,, ,, ,, ,, a typical stamen
3),, ,, ,, ,, ,, a mature embryo.
4)Describe the events of double fertilization.
5)Describe the structure of microsporangium.
Question carries 5 marks
1)Describe the structure of an ovule with figure.
2)Describe about pollination and all its types.
3)Explain the role of tapetum in the formation of pollen grain.
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CHAPTER-3
HUMAN REPRODUCTION
Sexual Reproduction:
It involves:
Gametogenesis : formation of sperm in male and ovum in female.
Insemination : transfer of sperm into female genital tract.
Fertilization : fusion of sperm and ovum to form zygote.
Implantation : development of blastocyst and its attachment to uterine wall.
Gestation : embryonic development.
Parturition : birth of the baby.
MALE REPRODUCTIVE SYSTEM :
It includes:
A pair of testis
Male accessory gland
Male accessory duct.
External genitalia
Testis -A pair of oval testis 4-5 cm. long 2-3cm wide are present in a pouch like structure called scrotum. Each testis has 250 compartment called testicular lobules.
Seminiferous tubules are highly coiled tubes present in lobules which contain two types of cells, male germ cell (spermatogania) and sertoli cells.
Interstitial space around seminiferous tubules contains interstitial cell or Leydig cells.
Function pf cell :-
Spermatogenesis : develop in to sperm
Sertoli cells : provide nourishment to developing sperm.
Leyding cell : secretion of androgen hormone.
Male Accessory Ducts:
These include rete testis, vasa efferentia, epididymis and vas deferens. These tubules form a very long & complicated system for storage and transport mature sperms.
A pair of vas deferens ascends to the abdomen and loop over urinary bladder.
Male Accessory Gland :
A pair of seminal vesicles.
A prostate gland
A pair of bulbo-urethral gland or Cowper’s gland: also help in lubrication of penis.
External genitalia: It consists of penis though which urethra opens out as urethral meatus. It has a swollen tip called glans penis covered by membrane called foreskin.
FEMALE REPRODUCTIVE SYSTEM :
It consists:
a)A pair of ovaries.
b)A pair of oviduct or fallopian tubes
c)Uterus
d)Cervix
e)Vagina
f)External genitalia
g)A pair of mammary gland.
Ovaries: These are primary female sex organ about 2-4cm long almond shaped, located on each side of abdomen to pelvic wall and uterus. Their function is to produce ovum and ovarian hormones i.e. estrogen and progesterone.
Oviducts or fallopian tubes : It is about 10-12cm long, extending from funnel shaped infundibulum near ovaries to uterus. Infundibulum leads to wider ampulla which is connect through isthmus to uterus on both sides.
Uterus : It is also called womb. It is inverted pear shape open into vagina through cervical canal. Uterus wall consist of three layers – perimetrium, myometrium and endometrium. Endometrium undergoes cyclic changes during menstrual cycle while myometrium has smooth muscles which help in parturition.
External genitalia : In consists of mons pubis, labia majora, labia minora, hymen and clitoris.
Mammary gland : A pair of Mammary glands produce milk during lactation. Glandular tissue of mammary gland is divided into 15-20 mammary lobes, which contain alveoli. Through lactiferous duct, milk is suck out of mammary gland.
Gametogenesis: Gametogenesis involves the formation of haploid gametes in gonads. In male, it is spermatogenesis and in female, it is oogenesis.
Spermatogenesis:
Spermatogonia
Mitosis
Primary Spermatocytes
1st Meiotic division
Secondary Spermetocytes
2nd Meiotic division
Spermatids
Spermatozoa
Oogenesis:
Oogonia
Mitosis
Primary Oocyte
1st Meiotic division
Secondary Oocyte
2nd Meiotic division
Ovum
Sl.
No.
Features
Spermatogenesis
Oogenesis
1.
Site Of Occurrence
Site of occurrence : In the
seminiferous tubules of testes
In the ovaries
2.
Yolk
Yolk is absent
Vitellogenesis occurs in growth
phase
3.
Number of Gametes
Number of gametes – One
spermatogonium forms 4 haploid
sperms
One Oogonium forms only one ovum
And three polar bodies
4.
Site Completion
Site of completion – It is started
and completed in the testes.
It is started inside the
ovary but completed outside
5.
Size of Gametes
Size of gametes – Smaller than spermatogonia
Ovum is much larger than oogonium.
Menstrual cycle :
It consists of cyclic changes in the ovaries which culminate into the periodic vaginal bleeding called menstruation. On an average, it is completed in 28 days. It consists of four phases:-
a)Proliferative phase
b)Ovulatory phase: It is characterized by rupture of Graafian follicle and release of ovum.
c)Luteal phase
d)Menstrual phase
Proliferative Phase : It involves growth and proliferation of uterine endometrium, fallopian tubes and vagina while ovulation occurs.
Luteal Phase: Characterized by change of empty Graafian follicle into a corpus luteum which secretes progesterone.
Menstruation Phase : It is followed by Luteal phase, if the ovum remains unfertilized. If fertilization occurs, it is followed by implantation and normal growth of foetus.
Fertilization and Implantation :
It includes four steps
a)Approach of sperm to ovum
b)Penetration of sperm into ovary
c)Activation of ovum
d)Fusion of gametic nuclei
Semen is released in the vagina during copulation. Fertilization is caused by the fusion of sperm and ova in ampullary – isthmic junction. Sperm causes changes in zona pellucida membrane to prevent polyspermy.
Main significance of fertilization is to restore dipliody.
Implantation leads to the beginning of pregnancy.
Cleavage is the process in which the zygote undergoes rapid mitotic divisions to form blastula. The cleavage initially forms a solid ball like morula. Morula changes into blastocyst.
Blastocyst enters the uterus about 72 hour after fertilization and gets implanted to endometrium of the uterus on to 7th day.
Blastocyst consists of inner cells and outer trophoblasts. Trophoblasts help its attachment with the endometrium while inner cells differentiate into ectoderm, mesoderm and endoderm. All major organs get formed till the embryo is 12 weeks from these three germ layers.
Pregnancy and Parturition :
Placenta: The Human placenta is formed by chorionic villi of trophoblast surrounded by uterine tissue and material blood for the developing embryo.
Placenta – (its significance)
Helps in exchange of oxygen and CO2 between the mother and the foetus.
Helps in the elimination of nitrogenous wastes of the foetus.
Acts as an endocrine gland and secrets a hormone such as HCG (Human Chorionic Gonadotropin), Human placental lactogen (hPL), estrogen and progesterone.
Parturition and Lactation:
Parturition: The process of vigorous contraction of myometrium to expel the foetus is called parturition.
Lactation: Colostrum is the first milk that is secreted from the mother’s mammary glands just after the child birth. It is rich in calories and proteins and also contains antibodies to provide passive immunity to the new born infant. Synthesis of milk is stimulated by the prolactin. Its release is stimulated by oxytocin.
ABBREVIATIONS:
1)GnRH : Gonadotrophin releasing hormone.
2)LH : Luteinising hormone
3)FSH : Follicle Stimulating hormone
4)hCG : Human chorionic gonadotrophin
5)hPL : Human placental lactogen
IMPORTANT FIGURES :
1)NCERT Page No. 43, fig No. 3.1 (b)
2)NCERT Page No. 44, fig No. 3.2
3)NCERT Page No. 45, fig No. 3.3 (b)
4)NCERT Page No. 47, fig No. 3.5
5)NCERT Page No. 48, fig No. 3.6
6)NCERT Page No. 49, fig No. 3.7
7)NCERT Page No. 51, fig No. 3.10
EXERCISE
Very short answer type questions (One Mark)
1. Which part in the male reproductive system stores sperms?
2. When a male is known as sterile?
3. What is the site for spermatogenesis?
4. In which part corpus luteum is formed?
5. Name the site of fertilization in humans?
Short answer type questions (Two Mark)
1. Describe the terms menarche and menopause.
2. Where are leydig cells located? Which hormone they secret?
3. What is pregnancy hormone? Why it is called so?
4. Define (i) Insemination (ii) Gestation
5. Give any four functions of placenta.
Short answer type questions (Three Mark)
1. Describe menstrual cycle in detail.
2. How does parturition takes place in humans?
3. Differentiate between spermatogenesis and spermatogenesis?
4. Describe the events taking place during embryogenesis?
5. How polyspermy is prevented in humans?
Long answer type questions (Five Mark)
1. Differentiate between spermatogenesis and oogenesis in human ?
2. Describe the various stages in the development of human embryo.
3. Describe the following:
Various stages of Spermatogenesis.
Various stages of oogenesis
Hormonal control of spermatogenesis
Hormonal control of oogenesis.
Structure of mature ovum.
CHAPTER-04
REPRODUCTIVE HEALTH
REPRODUCTIVE HEALTH:- It refers to as a total well being in physical, emotional, behavioral and social aspects of reproduction.
AMNIOCENTHESIS:- The process of detection of sex of an embryo is known as amniocentesis. It is carried out by testing of amniotic fluid of the developing foetus . It is a process which is misused to which the female child ratio becomes decreases.
CDRI- Central Drug Research Institute.
POPULATION EXPLOISION AND BIRTH CONTROL
Population explosion:- Increasing no. of individual per unit area is known as population explosion. It is due to decreased in (MMR) & (IMR).
*MMR-maternal mortality rate.
*IMR-infant mortality rate.
Birth control:- The regulation of conception by preventive methods or devices to limit the number of offspring is called birth control.
It can be carried out by three methods:-
1)Natural method:- avoiding foetus during the days from 10-17 days after menstrual cycle in which the changes of ovum formation is high. The automatic seizing of menstruation during the lactation makes a condition known as lactational amenorrhea, in which no ovum is formed(less the chance of fertilization).
(a) Safe period:- a week before and a week after menses is considered as the safe period for sexual intercourse. The ideas based on the following facts::
---ovulation occurs on about 14th day(may be 13th to 16th day) of menstruation.
---ovum survives for about 1-2 days.
---sperms remain alive for about 3 days.
This method may reduce the chances of pregnancy by about 80%. However, a great care is needed in its use.
(b) Coitus Interruptus:- this is the oldest method to birth control. It involves withdrawal of the penis from the vagina by the male before ejaculation so that the semen is not deposited in the vagina and there is no fertilization.
(c) Lactational Amenorrhea:- it is based on the fact that ovulation and therefore the menstrual cycle do not occur during the period of intense lactation following child birth(parturition). This method is considered effective only upto a maximum period of six months following parturition and has no side effects.
2)Barrier method:- by avoiding the contacts sperm and ovum by using physical barriers like cervical caps and intrauterine Device. Also by taking various female hormones in the forms of contraceptive peels.
IUDs- It is generally made up of coppers and which is commonly known as copper-T which is allowed to present inside the uterus which releases the copper ion which sterilized the active sperm and also disturbs the embryo just after sterilization.
3)Surgical method:- this is also known as sterilization. The mature sperm and ovum are not allowed to meet with each other. It advised for the male/female partner as a terminal method to prevent any more pregnancies. Surgical intervention blocks gamete transport and prevents conception.
Vasectomy sterilization procedure in the male.
Tubectomy sterilization procedure in the female.
MEDICAL TERMINATION OF PREGNANCY
Intentional or voluntary of pregnancy before the foetus becomes viable is called medical termination of pregnancy or induced abortion. It is a process of destroying the developing embryo due to certain imbalance in health of female. During this process the developing embryo is checked by the application of chemicals or physically disturb by the help of needle after this destroyed cells of embryo sucked out from the uterus. It is safe upto 12 weeks of pregnancy.
It is one of the most widely used methods of fertility control. Nearly 45 to 50 million induced abortions are performed in a year in all over the world, which account to 1/5th of the total number of conceived pregnancies in a year.
*Why MTP?
--- MTP is done to get rid of unwanted pregnancies due to:
(a). Casual unprotected intercourse. (b). Rapes.
(c). Failure of contraceptive used during coitus.
SEXUALLY TRANSMITTED DISEASES (STDs)
These are the disease which is generated due to disturbances of hormonal secretion or also by various physical agents mainly by bacteria and virus, commonly known as STDs or VD or RTI.
Examples:- HIV leading to AIDS, gonorrhea, syphilis, genital herpes, chlamydiasis, genital warts, trichomonasis, hepatitis-B are few common STDs.
Though all persons are vulnerable to these infections, their incidence is very high among adolescents in the age group of 15-24 years.
SOME COMMON STDs AND THEIR CAUSATIVE AGENTS.
Sl.no
Infection/Disease
Causative Agents
01.
HIV/AIDS
Human Immuno Deficiency Virus
02.
Gonorrhea
Neisseria gonorrhea(bacteria)
03.
Syphilis
Trepanoma palladium(bacteria)
04.
Chlamydiasis
Chlamydia trachomatis
05.
Genital herpes
Herpes Simplex Virus
06.
Hepatitis-B
Hepatitis Virus
07.
Trichomoniasis
Trichomonas vaginalis(protozoan)
SOME MEASURES TO PREVENTFROM CONTRACTING STDs
(1). Creating awareness to limit the number of sexual partners, particularly in young people.
(2). Use condoms.
(3). Avoid sharing of injection needles, surgical instruments etc.
(4). In case of doubt, immediately specialists must be contacted for early detection and cure of
STDs, get complete treatment if diagnosed with disease.
INFERTILITY
The process of natural failure of fertilization which takes place due to abnormal hormonal secretion or any genetical failure meant for fertilization. It is inability to conceive and produce children inspite of unprotected sexual cohabitation. Such a phenomenon is termed as infertility.
ASSISTED REPRODUCTIVE TECHNOLOGIES(ART)
These are the special techniques to overcome infertility or which assist infertile couples to have children.
SOME PROMINENT TECHNIQUES ARE:-
(1). “Test tube baby” programme.
(2). Gamete intra fallopian transfer (GIFT).
(3). Intra cytoplasmic sperm injection (ICSI).
(4). Artificial insemination technique (AIT).
IMPORTANT ABBREVIATIONS :-
1. WHO World health organization.
2. RCH Reproductive and child health care programme.
3. STD Sexually transmitted diseases.
4. CDRI Central Drug Research Institute.
5. MMR Maternal mortality rate.
6. IMR Infant mortality rate.
7. IUDs Intra Uterine Devices.
8. MTP Medical Termination of Pregnancy.
9. VD Venereal Diseases.
10. RTI Reproductive Tract Infection.
11. AIDS Acquired Immuno Deficiency Syndrome.
12. PID Pelvic Inflammatory Diseases.
13. ART Assisted Reproductive technologies.
14. IVF In Vitro Fertilization.
15. EF Embryo Transfer.
16. ZIFT Zygote Intra Fallopian Transfer.
17. IUT Intra Uterine Transfer.
18. GIFT Gamete Intra Fallopian Transfer.
19. ICSI Intra Cytoplasmic Sperm Injection.
20. AIT Artificial Insemination Technique.
21. IUI Intra Uterine Insemination.
22. CVS Chronics Villus Sampling.
IMPORTANT DIAGRAMS:-
1.NCERT TEXT BOOK *Fig 4.4a (Vasectomy)
2.NCERT TEXT BOOK *Fig 4.4b (Tubectomy)
EXERCISE
Very short answer type questions (One mark)
1. Name any natural method of birth control.
2. Name any copper releasing IUD.
3. Name the organization that produce “Saheli” pill.
4. List two most common STDs.
5. Name the technique used for determining the sex and condition of the foetus.
Very short answer type questions (Two marks)
1. Name two new techniques for determining the condition of the foetus.
2. Give the sex chromosomes of man and woman.
3. List major aims and objectives of RCH programmes.
4. Name the oral pill which is taken up by Indian woman once a week.
5. List causative agents of the following STDs. (I) AIDS (II) Gonorrhea.
Very short answer type questions (Three marks)
1. What are test tube babes?
2. Write a note on chorionic villus sampling (CVS).
3. Why medical termination of pregnancy is done?
4. Briefly describe gamete intra fallopian transfer (GIFT) technique.
5. Explain the following: (a) Artificial insemination technique (b) In vitro fertilization.
Very short answer type questions (five marks)
1. What is birth control? Briefly explain various temporary methods of birth control.
2. Explain the following. (a) MTP (b) Permanent method of birth control.
3. Explain various special techniques used in assisted reproduction technologies (ART).
4. What are the requirements of pregnant woman?
5. Describe a techniques by which genetic disorders in the developing foetus can be detected.
UNIT VII
GENETICS AND EVOLUTION
Chapter : 5
Principles of
Inheritance & Variations.
1. Principles of inheritance and variation.
* Heredity is the transference of characters from one generation to the subsequent generation i.e. parents to offspring.
*Inheritance is the process by which characters are passes on from parents to progeny.
*Variation means differences between individuals of same species.
*genetics is the branch of biology which deals with the study of inheritance.
2. Gregor Johann Mendel
*Gregor Johann Mendel (1822 – 1884) is known as father of genetics.
*Mendel Carried out Hybridization experiments on Garden Pea for 7 years (1856 – 1863).
3. Mendel selected following characters / traits for his experiments.
S. No.
CHARACTER
DOMNENT
RECESSIVE
01.
Plant height
Tall(T)
Dwarf (t)
02.
Flower Position
Axial (A)
Terminal (a)
03.
Pod Shape
Full / Inflated (F)
Constricted (f)
04.
Pod Colour
Green (G)
Yellow (g)
05.
Flower Colour / Seed Coat Colour
Violet / Red (V or R) Grey
White (v or r) / White
06.
Seed Shape
Round (R)
Wrinkle (r)
07.
Seed Colour
Yellow (Y)
Green (y)
4. Law of Dominance:
a) Characters are controlled by discrete units called factors.
b) Factors occur in pair.
C) In a dissimilar pair of factors one member of the pair dominates (dominant) the other (recessive).
d) In F1 generation only one allele is able to express its effect in the individual.
5. Law of Segregation:
The two allelomorhic characters of an individual do not get mixed up by they segregate during gamete formation. Each gamete receives only one character of the two allelomorphs and a pair condition is restored by random fusion of gametes during fertilization.
6. Test Cross:
It is a cross between F1 hybrid and the recessive parent.
To confirm the purity of F1 hybrid, whether it is homozygous, a test cross is done.
a) If the test cross yields off springs of 50% dominant and 50% recessive character, then the F1 hybrid is heterozygous. It shows (1:1) test ratio for monohybrid cross and (1:1:1:1) for dihybrid cross.
b) If the test cross yields all the dominant character, the F1 hybrid is homozygous.
7) Back Cross:
Which a inter cross is done between two genetically different parents, a hybrid is produced which may be homozygous are heterozygous. To determine the purity of parents & to test genotype of F1 Hybrid, a cross is made between F1 hybrid and on of the parent. Such a cross is known as back cross.
8) Exception of Principle of Dominance:
A) Incomplete Dominance: When two parents are inter crossed with each other, the hybrid that produced does not resembled either of the parents but is midway between the two parents(dominant and recessive parents), i.e., the expression of the character in a hybrid or F1 individual is intermediate on a fine mixture of the expression of the two factors.
The phenomenon of incomplete dominance occurs in four ‘O’ Clock plant (Mirabilis jalapa) & Snapdragon (Antirrhinum majus) and Andalusian fowls.
B) Co-Dominance: when both alleles of a pair are fully expressed in a heterozygote, the genes and trait are said to be co-dominant.
Examples:
AB Blood Group.
Sickle Cell Anaemia
C) Multiple Alleles: More than two alternate forms of a gene present on the same locus are called multiple alleles.
Examples:
Inheritance of blood group.
9. Principle of Law of Independent Assortment:
When two pairs of independent alleles are brought together, they show independent dominant effects. During the formation of gametes the genes of different characteristics are independent of one another.
10. Chromosomal theory of Inheritance:
Walter Sutton and Theodor Boveri proposed the Chromosome theory of Inheritance. Main features of chromosome theory of inheritance:
Nucleus contains chromosomes. Therefore, chromosome must carry the heredity traits.
Gametes contain only one chromosome of a type and only one of two alleles of trait.
The pained condition of both chromosomes as well as Mandelian factors is restored during fertilization.
Each chromosome contains numerous genes & the positions assigned to each gene is called locus. These genes help the organism to develop from the Zygote.
Each chromosome retains its individuality, uniqueness & continuity throughout the life of an organism and from generations to generation. They never get last or mixed up but behave as units.
11. Linkage & Recombination:
A chromosome contains large number of genes in a linear order and these genes belonging to a particular chromosome tend to be inherited together. This tendency of genes to remain together during the process of inheritance is called as linkage. Morgan (1990) proved and defined linkage on the basis of his breading experiments in fruitfy (Drosophila melanogaster).
Morgan etal observed that when two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combination were much higher than the non parental types.
Morgan attributed this to the physical association of the two genes which he referred as linkage and the term recombination to the non-parental combinations different from the parental types.
12. Linkage maps or Chromosomes Maps:
A linkage or genetic chromosome map in a linear respiration of the sequence & relative distances of the various genes present in a chromosome. The first chromosome maps were prepared by Sturtevant in 1911 from two chromosome of Drosophila.
13. Determination of Sex:
Chromosome theory of sex put forwarded by Wilson and Stevens (1950) and named X and Y bodies as sex chromosomes, X and Y.
It is of the following types:
XX – XY type found in human beings.
XX – XO type found in grass hoppers, cockroaches and bugs.
ZW –ZZ type found in birds and some reptiles.
ZO – ZZ type found in butterflies & moths.
14. Genetic Variations:
Mutation – it is the sudden, discontinuous and heritable change which alters the phenotype of an individual. The term “mutation” was coined by Hugo de Vices (1901).
Types of mutation due to change in structure of chromosome.
Chromosomal mutation may alter the structure of chromosomes.
Deletion (Deficiency) – A segment of chromosome separate and lost.
Duplication – It is the phenomenon of having an extra chromosome segment attached to a normal segment.
Inversion – A segment of chromosome separates and rejoins at in an inverted position. It results in the change in sequence of nitrogenous base or genes in chromosome.
Point mutation is the abrupt change in gene structure due to change in a single base pair of DNA due inversion and substitution, without changing the reading of subsequent bases.
Example: Sickle Cell Anaemia.
Frame shift mutation is the elimination or addition of one or two base pairs or a segment of DNA in a gene. It leads to chain of triplet codon on m-DNA that is responsible for polypeptide chain. It results in lateral sifting of entire reading frames from the site of mutation.
Thalassemia – an inherited blood disorder is an example of frame shift mutation.
15. Pedigree Analysis:
It is a chart to represent the data collected from a family over a number of generations for a certain genetic trait by using international conventional symbol. It reveals the ancestral history of an individual and its possible genotype for a trait.
16. Human Genetic Disorders:
a) Mendelian Disorders:
I) Sickle Cell Anaemia: Sickle cell Anaemia is an autosomal hereditary disorder in which
The erythrocytes form biconcave disc to elongated sickle like structure under low oxygen deficiency as during strenuous exercise and at high altitudes.
The disorder or disease is caused by the formation of abnormal haemoglobin
called Haemoglobin-S which differs from normal Haemoglobin-A in only one Amino Acid
– 6th amino acid of B-Chain, glutamic acid is replaced by valine.
II) Phenylketonuria: it is an inborn error of metabolism which is inherited as autosomal recessive trait. The affected individual do not produced phenylalanine hydrolase which converts phenylalanine to tyrosine. So, in the absence of this enzyme, phenylalanine accumulates in the blood & produces toxic effect on CNS resulting irreversible brain damage, severe mental & physical retardation.
III Haemophilia: It is a sex linked disorder and it is also known as bleeder’s disease as the patient will continue to bleed even from a minor cut since he or she does not possess the natural phenomenon of blood clotting due to absence of anti haemophilic globulin or factor VIII and plasma thromboplastin factor IX essential for it.
b) Chromosomal Disorders:
I) Down’s syndrome: a) Trisomy of chromosome no.21.
b) Short stature, Round head, Furrowed Tongue and retarded Development.
II) Turner’s Syndrome: a) Absence of one of the X chromosome (karyotype of 45 chromosomes)
b) Sterility, Lack of secondary sex characters.
III) Klinefelter’s Syndrome: a) Additional copy of X chromosome.
b) Sterility, masculine development with some feminine features & development of breast, i.e., Gynaecomastia.
EXERCISE
PART – A: Very Short Answer Questions (VSA – 1 Mark)
1. Name the two kinds of linkage.
2. Write Mendel’s dihybrid ratio of phenotypes.
3. Who proposed chromosome theory of inheritance?
4. Who shows that the gene lie in the chromosome?
5. Which Mendel’s law of inheritance is universally acceptable, with out any exception?
6. The gene I that controls the ABO blood grouping in human beings has three alleles IA, IB and
i) How many different genotypes are likely to be present in the human pollution?
ii) Also how many phenotypes are possibly present?
PART – B: Short Answer Questions (SA – 2 Marks)
1. Write any three abnormalities linked with sex chromosomes.
2. “A white eyed female drosophila was mated with red eyed male.” , What will be the
phenotypes of male & female progeny?
3. Write briefly the contribution of J H Morgan in genetics.
4. List the main points of chromosome theory of inheritance.
5. What do you mea by Pedigree analysis?
PART – C: Short Answer Questions (SA – 3 Marks)
1. Write a note on sex linked genes.
2. What is point mutation? Mention two autosomal genetic disorders with their symptoms.
3. What are the advantages of selecting pea plant for experiment by Mendel?
PART – D: Large Answer Questions (LA – 5 Marks)
1.
a) Differentiate
i) Dominance & Recessive ness
ii) Monohybrid & Dihybrid.
b) Who is called father of experimental genetics
2. Write various conclusions and hereditary principles drawn by Mendel from a Monohybrid cross.
3. Give a detailed account of any two of the following Mendelian disorders:
a) Sickle Cell Anaemia.
b) Haemophilia.
c) Phenylketonuria.
ANSWERS OF PART – A
Complete & Incomplete.
9:3:3:1.
Sutton and Boveri proposed chromosome theory of Inheritance.
Morgan (1910, Bridges (1916).
Law of segregation is universally accepted.
i) IAIA, IAIO, IBIB, IBIO, IAIB, IOIO (six only). ii) A, B, AB, O (Four Only).
Additional Questions with Answers:
1.Define the following terms
a.Homozygous,
b.Heterozygous
c.Dominant genes
d.Recessive gene
e.Genotype
f.Phenotype
g.Alleles.
Answer:
a.Homozygous: An individual, who possesses two identical alleles at a particular locus on homologous chromosome, is called homozygous.
b.Heterozygous: An individual who possesses two different alleles at one particular locus on homologous chromosomes, in called heterozygous.
c.Dominant Gene: A which is always expressed both in homozygous, is called dominant gene. e.g. Tall stem in a pea.
d.Recessive Gene: A gene that is expressed only in homozygous form is called as recessive gene.
e.Genotype: It is the total genetic contribution of an individual or more specially the alleles present at one locus for a particular trait.
f.Phenotype: It is the appearance of an individual (physical, biological, physiological) which is produced by the expression of genotype under the influence of environment.
g.Alleles: Genes which code for a pair of contrasting trait are known as alleles.
2.Differentiate between
a.Dominance & Recessive-ness
b.Homozygous & Heterozygous.
c.Monohybrid & Dihybrid.
d.Incomplete dominance & Co-dominance.
Answer:
a.
Dominance
Recessive-ness
1.Dominant gene or factor is able to express it self even in the presence of its recessive allele.
2.It expresses it self because it forms complete polypeptide or enzyme of expressing its effect.
1.Recessive ness or factor is unable to express itself in the presence of dominant gene.
2.The recessive gene forms an incomplete polypeptide or enzyme thus fails to express its effect.
b.
Monohybrid
Dihybrid
1.An individual heterozygous for allele at one gene locus is called monohybrid.
2.It reveals to the Mendel’s law of segregation.
1.An individual heterozygous at two gene loci is called dihybrid.
2.It reveals to the Mendel’s La w of independent assortment of gene.
c.
Homozygous
Heterozygous
1.Homozygous individual is pure for a trait & breeds true or gives rise to similar homozygous individual.
2.The alleles are similar.
3.It produces one type of gametes.
1.Heterozygous individual is not pure & produces offspring with different genotypes on selfing.
2.The alleles are dissimilar.
3.It produces two types of gametes.
d.
Incomplete Dominance
Co-Dominance
1.Effect of one of the two alleles is more conspicuous.
2.It produces a fine mixture of the expression of two alleles.
3.The affect in hybrid is intermediate of the expression of the two alleles.
1.The effect of both the alleles in equally conspicuous.
2.There is no mixing of the effect of the two alleles.
3.Both the alleles produce their effect independently.
Chapter : 6
Molecular basis
Of Inheritance
Nucleic Acids: The polynucleotide chains of very high molecular weight are called nucleic acids. They are the genetic material of lining.
1. Deoxyribonucleic Acid (DNA):
# DNA is a long polymer of deoxyribonucleotides.
# the length of DNA is defined as the number of nucleotides present in it.
2. Structure of DNA:
* DNA is formed of number of nucleotides units.
* Each nucleotide has a nitrogenous base, a pentose sugar and inorganic phosphate.
* Nitrogen basis occur in DNA belonging to tw0o groups, purine and pyrimidine.
* DNA has two double ring of purines (Adenine-A and Guanine-G) and two single ring pyrimidine (Cytosine-C and Thymine-T)
* A nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage to form a nucleoside.
* When a phosphate group is linked to 5 – OH of a nucleoside through phosphodiester linkage, a corresponding nucleotide is formed.
* The two chains are held together by two hydrogen bonds between adenine-A with Thymine-T and by three hydrogen bonds between Guanine-G with Cytosine-C.
* The two DNA chains are antiparallel that is, they run parallel but in opposite directions. In one chain the direction 5’ -> 3’ while in the opposite one it is 3’ -> 5’.
3. Double Helix Model of DNA.
* DNA is double helix and formed of two polynucleotide chains which are coiled with one another in a spiral.
* The nucleotides in a polynucleotide chain are linked together by phosphodiester bond.
* The two chains of DNA have anti parallel polarity 5’ -> 3’ in one and 3’ -> 5’ in other.
* Nitrogen bases of two polynucleotide chains form complementary pairs, A opposite to T & G opposite to C.
* The helix has a constant diameter of 20Ao (2nm) throughout its entire length.
* The pitch of helix in 3.4nm (34Ao) with roughly 10base pairs in each turn. The average distance between base pairs comes to about 0.34nm.
4. DNA as Genetic Model: (Griffith’s Experiment).
* It is the change in the genetic constitution of an organism by picking up genes present in the remains of its dead relatives.
* Transformation was first studied by S.F Griffith in1928 while studying on bacterium Streptococcus pneumoniae called pneumococcus.
* The bacteria has two strains – the smooth form(s) secretes a polysaccharide capsule which gives the colonies a smooth appearance and virulent. Another form is non-capsulated which gives the colonies a rough appearance and is not virulent (R)
*Griffith tested the virulence of the two strains by injecting the live R-type and live S-type separately into mice, he found that R-type bacteria were non-pathogenic while the S-type caused the death in the mice.
*Heat killed S-type bacteria into mice and they survived equally well
* In the last, he injected a mixture of heat killed “S” & live “R” simultaneously, the mice died with the symptoms of pneumonia. Living type S bacteria were recovered from their bodies.
S-type R-type S-heat killed S-Heat Killed + R-type
Mice Mice Mice Mice
Died Alive Alive Died
This happened because something from the dead bacteria had entered the live ones & made them virulent.
* He concluded that the R-strain bacteria had been transformed by the heat killed S-type, which must be due to the transfer of the genetic material (Transforming Principle).
5. Hershey and Chase experiment.
Alfred Hershey and Marth Chase (1952) indicated that DNA is the genetic material and not the protein.
* Viruses that infect bacteria is called bacteriophage.
* The bacteriophage attaches to the bacteria & its genetic material enters the bacterial cell by dissolving the cell wall of bacteria.
* They grew some viruses on a medium that contained radioactive phosphorus
and other on medium that contained radioactive Sulphur.
* Virus grown in the presence of radioactive Phosphorus contained radioactive DNA but not radio active protein because DNA contains phosphorus but protein does not.
* Similarly viruses grown on radioactive Sulphur contained radioactive protein but not radioactive DNA because DNA dose not contain Sulphur.
* Radioactive phases were allowed to attach to E.coli bacteria then as the infection preceded the viral coats were removed from bacteria by agitating them in a blender. The virus particles were separated from the bacteria by spinning them in a centrifuge.
* Bacteria that were infected with virus had radioactive DNA were radioactive, indicating that DNA was the material that passed from the virus to bacteria. Bacteria that were infected with the viruses that had radioactive proteins were not radioactive. This indicates that proteins did not enter the bacteria from the viruses. DNA is therefore the genetic material that is passed from virus to bacteria.
6. Mode of DNA Replication
DNA replication occurs during S-phase of cell cycle.
Mechanism of DNA replication is as follows:
* The starting point where replication of DNA begins at a specific point were inter wind DNA segments start unwinding called origin of replication.
* Since the two strand cannot be separated in its entire length (due to very high energy requirement) replication occurs with small opening of the DNA-helix; the Y shaped structure formed is called replication fork.
* The DNA-dependent DNA-polymerases catalyze polymerization of the nucleotides only 5’ -> 3’.
* Consequently on one of the template strands (with 3’ -> 5’ polarity) the synthesis of DNA is continuous, while on the other template strand (with polarity 5’ -> 3’), the synthesis of DNA is discontinuous, i.e. short stretches of
DNA are synthesized known as Okazaki fragments.
* The discontinuously synthesized fragments are later joined by the enzyme DNA-ligase.
* As one strand grows continuously while the other strand is formed discontinuously DNA replication is semi discontinuous.
7. Transcription
* The process of copying genetic information from one strand of the DNA into RNA is called transcription.
* Principles of complementarities govern the process of transcription; the exception is that uracil is incorporated instead of thymine opposite adenine of template.
* Only a segment of DNA is transcribed and that only one of two strands is copied.
* Both the DNA strands cannot be copied in transcription because that will produce two types of proteins, one with correct sequence of amino acids and the other with reverse sequence of amino acids.
* Further if two complementary RNA’s are produced simultaneously, they would have a tendency to form double stranded RNA resulting in non translation of coded information into proteins. The whole exercise of transcription would then appear futile.
* Transcription Unit. The segment of DNA that takes part in transcription unit it has three components:
1) A promoter,
2) The Structural gene, and
3) A terminator.
Besides a promoter, eukaryotes also require an enhancer.
* Promoter is located upstream of structural gene. By convention it is called 5' end (of coding strand which is 3’ end of template strand).
*Terminator region is present down stream of structural gene at the 3’ end (of coding strand which is actually 5’ end of the template strand).
* Structural gene is component of that DNA strand which has 3’ – > 5’ polarity (as transcription occur only in 5’ <– 3’ direction). This strand of DNA is called template strand.
* The other strand which has a polarity of 5’<– 3’ is displaced during transcription. This non-template strand which does not take part in transcription is also called coding strand or plus(+) because genetic code present in this strand is similar to genetic code (based on mRNA) except that uracil is replaced by thymine.
8. Genetic Code:
The relations hip between the sequence of amino acids in a polypeptide and nucleotide sequence of DNA or mRNA is called genetic code. There are 64 codons in the genetic code. Out of 64 codons UAA, UAG & UGA do not represent to any amino acid and are called non-sense or termination codons.
Salient features of genetic code:
It is triplet (made of 3 letters).
Non-Ambiguous & specific codons. One codon codes for only one amino acid and
not any other.
The code is degenerative. More than one codon can code for same amino acid. Example, Phenylalanine has two and arginine has six codons.
The code is comma less. There is no punctuation between any of the codon triplets.
The code is non-overlapping. It means that same latter cannot be used for two different codons.
The code is nearly universal. Exceptions are these in mitochondrial codons, and in some protozoa’s
AUG has dual functions. It codes for Methionine (met), and it also act as initiating codon.
9. Protein Synthesis:
Mechanism of Protein synthesis in E.coli is given below:
The entire process of protein synthesis can be divided into two stages- Transcription and Translation.
Amino acids are regarded as building blocks of proteins.
Carboxyl group (-COOH) of one amino acid is bonded with amino group (-NH2) of another amino acid by a Peptide bond.
Several amino acids are linked by Peptide Bonds to form Poly Peptide chain.
Transcription:
The process of transmission of Genetic information from template strand of DNA to m-RNA is called Transcription .The site of transcription is nucleus.
It requires DNA template, nucleotide triphosphates, RNA polymerase, & Mg or Mn ions.
Transcription begins with uncoiling of the two strands of DNA. One strand of DNA acts as a template for m –RNA formation. By the action of RNA polymerase m-RNA is formed according to the triplet code of DNA by copying process.
m–RNA comes out of the nucleus and attaches itself to the ribosomes.
STEPS IN VOLVED IN TRANSLATION
Attachment of m- RNA TO RIBOSOMES
Activation of amino acids
Initiation of amino acids
Polypeptide chain elongation
Polypeptide chain termination
TRANSLATION
Arrangement of amino acids in specific sequence & formation of polypeptide chain according to the information present in m-RNA is called translation.
Site of translation is ribosomes.
Translation is a complex process which involves the participation of ribosomes, m-RNA, t-RNA& amino acids
Attachment of mRNA to ribosomes
mRNA binds with 30 s ribosomal sub unit with its initiation codon AUG:
At times GUG also acts as initiation codon.
The group of ribosomes present on the mRNA molecule is called poly ribosome
ACTIVATION OF AMINOACIDS
Amino acids are scattered in the cytoplasm , they are in inactive state.
They are activated by specific aminoacyl t-RNA Synthetase enzymes,ATP is also required
Amino acids + ATP AA – AMP complex +PP
Amino acyl t-RNAsynthetase
These enzymes possess two binding sites one for amino acid and the other for its t-RNA.
Initiation of polypeptide chain
It requires amino acyl t- RNA complex ,m-RNA with initiation codon,30 s and 50 s subunits of ribosomes,GTP& initiation factors.
With the help of anticodon UAC, t-RNA carries FORMYL METHIONINE and attaches to AUG codon of m- RNA and forms initiation complex .
Both are linked together with hydrogen bonds.
t-RNA is linked to m- RNA at decoding site.
POLYPEPTIDE CHAIN ELONGATION
Formyl methionine moves from decoding site. A second amino acid is brought to A site by another aminoacyl t-RNA.A peptide bond is formed between the amino acids
Water is formed in this reaction .The movement of dipeptide from A site to P site is called Translocation.
POLYPEPTIDE CHAIN TERMINATION
Terminator or non sense codons (UAA, UAG, &UGA) present on the m-RNA strand signal the termination of polypeptide chain.
The last m-RNA and t-RNA are also set free.
Ribosomes dissociates into 30 S and 50 S subunits.
10. The Lac-Operon:
* The Lac-Operon consists of one regulatory gene (i), three structural genes(z,y,a), operator gene(o) & promoter gene(p).
* In Lac-Operon the regulator gene is called i-gene because it produces an inhibitor or repressor. The repressor binds to operator gene and turn off the Operon. It exerts a negative control over the working of structural genes.
* Structural genes are those genes which actually synthesize mRNAs. The Lac-Operon of E-Coli contains three structural genes (z, y, a).
* The ‘z’ gene codes for -galctosides which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units galactose and glucose. The ‘y’ gene codes for permease, which increases permeability of the cell to -galctosides. The ‘a’ gene encodes a transacetylase.
* Operator gene is a gene which directory controls the synthesis of mRNAs over the structural gene. It is switched off by the presence of a repressor. An inducer can take away the repressor and switch on the gene. When switch on the structural gene synthesis of polypeptide chain, i.e., transcription and translation occur.
* Promoter gene acts as an initiation signal which functions as recognition centre for RNA polymerase provided the operator gene switch on. RNA polymerase is bound to the promoter gene. When the operator gene is functional, the polymerase moves over it and it reaches the structural genes to perform transcription.
* The repressor of the operon is synthesized from the i-gene. The repressor protein binds to the operator region of the operon and presents RNA polymerase from transcribing the operon. In the presence of an inducer such as lactose or allolactose, the repressor is inactivated by interaction with the inducer. This allows RNA polymerase access to the promoter and transcription proceeds.
* Inducer regulator switching on of the operon. The inducer of Lac-operon of Escherichia coli is lactose (actually allolactose).
Human Genome Project (HGP)
Human Genome Project was called a mega project. The project was a 13-years project coordinated by the U.S Department of Energy and the National Institute of Health. The Project was completed in 2003. HGP was closely associated with the rapid development of a new area in biology called as Bioinformatics.
Goals of HGP
Some of the important goals of HGP were as follows:
(i)Identify all the approximately 20,000-25.000 genes in human DNA;
(ii)Determine the sequences of the 3 billion chemical base pairs that make up human DNA;
(iii)Store this information in databases;
(iv)Improve tools for data analysis;
(v) Transfer related technologies to other sectors. such as industries;
(vi)Address the ethical, Legal, and social issues (ELSI) that may arise from the project.
Salient Features of Human Genome Project
1.Human genome has 3164.7 billion nucleotide bases.
2.The average gene size is 3000 base pairs with sizes vary much. The largest gene being dystrophin at 2.4 million base pairs.
3.The human genome consists of about 30,000 gene much lower than previous estimates to contain 80,000 to 1,40,000 genes.
4.The function of over 50% of discovered genes is unknown.
5.Less than 2% of the genome code for proteins.
1.99.9% of the nucleotide bases are exactly similar in all human beings.
2.At about 1.4 million locations occur single nucleotide differences called SNPs (snips) or single nucleotide polymorphism. They have the potential to help find chromosomal locations for diseases associated sequences and tracing human history.
3.Repetitive sequences are nucleotide sequences that are repeated many times, sometimes 100 to 1000 times. They have the direct coding functions but provide information's as to chromosome structure, dynamics and evolutions.
4.Chromosomes I has most genes (2968) and Y has the fewest (231).
Applications of Future Challenges of HGP
1.Detection of Cancers: Efforts are in progress to determine genes that will change cancerous cells to normal.
2.Healthy Living: It will indicate prospects for a healthier living, designer drugs, genetically modified diets and finally our genetic identity.
3.Knowledge of Interactions: it will be possible to study how various genes and proteins work together in an interconnected network.
4.Study of tissues: all the genes or transcripts in a particular tissue, organ or tumor can be analyzed to know the cost of effect produced in it.
DNA Finger Printing
1.Alee Jeffrey’s (1984) invited the DNA fingerprinting technique at Leicester University. U K. Dr. V. K. Kashyap and Dr. Lalji Singh started the finger printing technology in India.
2.DNA Finger printing is a technique to identify a person on the basis of his / her DNA specificity by the means of their digital / palmer print. Each person has a unique DNA finger print.
Principles of DNA Printing:
1.Based pairs of DNA by their differences, about 0.1% or 3 X 106 base pairs (out of 3 X 106 bp) provided individuality to each human being. DNA fingerprinting involves identifying differences in specific regions in DNA sequence called as Repetitive DNA because in these sequences a small stretch of DNA is repeated many times. These repetitive DNA are separated from the bulk genomic DNA as different peaks during density gradient centrifugation. The bulk DNA forms a major peak and the other small peaks are referred to as Satellite DNA
2.Depending upon length, base composition and numbers of repetitive units, satellite DNAs has subcategorizes like micro satellites and minisatellites.
3.Satellite DNAs show polymorphism.
4.If a variant at a locus is present with a frequency of more than 0.01 populations, it is called DNA polymorphism.
5.Variations occur due to mutations, therefore, DNA polymorphism is the occurrence of mutations in a population at high frequency.
6.Short nucleotide repeats in the DNA are very specific in each individual and vary in number from person to person but are inherited. These are Variable Number Tandem Repeats (VNTRs) also called minisatellites.
7.Each individual inherits these repeats from his / her parents which are used as genetic markers in a personal identity test.
Techniques of DNA Finger Printing:
1.The DNA is extracted from the nuclei of white blood cells or of spermatozoa or of the hair follicle, skin, bone, saliva, etc.
2.The DNA molecules are first digested with help of enzyme restriction endo-nuclease that cuts them into fragments. The fragments of DNA also contain the VNTRs.
3.The fragments are separated according to size by gel electrophoresis.
4.VNTRs are multiplied through PCR technique.
5.The separated fragments of DNA in the gel are copied on to a nylon paper by Southern Blotting Technique.
6.Special DNA-probes are made in the laboratories which contain repeated sequence of bases complementary to those on VNTRs. These probes are made radioactivity by labeling with radioactive isotopes. The radioactive DNA-probes bind to the repeat sequences on the nylon membrane.
7.An X-ray film is exposed to the nylon membrane to mark the places where the radioactive DNA has bound to the DNA fragments. These places are marked as dark bands when X-ray film is developed. This is known as autoradiography.
8.The dark bands on X-ray film represent the DNA fingerprints (DNA Profiles)
Application of DNA fingerprinting:
1.In forensic laboratories for identification of criminals.
2.Paternity disputes to find real parents can be solved by DNA fingerprinting.
3.It is useful in determining population and genetic diversities.
4.It is used to study the breeding patterns of animals facing the danger of extinction.
Exercise
PART – A: Very Short Answer Questions (VSA – 1 Mark)
1.Name the enzymes which can break and reseal the DNA strand.
2.What are exons?
3.Which are three nonsense codons?
4.What function a tRNA plays?
5.Which are the start signals or initiator codons?
6.Expand VNTR.
PART – B: Short Answer Questions (SA – 2 Marks)
1.List three main differences between DNA & RNA.
2.Differentiate between leading strands and lagging strands.
3.Define genetic code.
4.Which molecule bears codons and which molecule anticodons?
PART – C: Short Answer Questions (SA – 3 Marks)
1.What is DNA fingerprinting? Mention its application.
2.Differentiate between Repetitive DNA & Satellite DNA.
3.What are the prospects of Human Genome Project?
PART – D: Large Answer Questions (LA – 5 Marks)
1.Explain briefly the difference steps in protein synthesis.
2.Explain the function of the following:
a.Promoter
b.tRNA
3.Explain how does lactose cause a “switch on” the Lac-Operon.
Answers to Part – A
1.Topoisomerase
2.These are the essential regions of a gene which become a part of mRNA during transcription & code for different regions of the amino acid.
3.UAA, UAG, & UGA
4.It is an adaptor molecule which carries specific amino acids from the cytoplasm to the ribosomal sites for the formation of polypeptide chain according with the sequence specified by mRNA.
5.AUG on Methionine.
6.Variable Number of Tandem Repeats.
Answers to Part – B
1.
2.DNA polymerase catalyses synthesis of DNA and helps also in proof reading.
3.The sequence of triplet bases specifies one amino acid in a polypeptide.
4.mRNA bears codons & tRNA molecule bears anti codons.
Additional Questions with Answer
1.What does an excess of tryptophan cause a “switch off” of the tryptophan Operon?
Answer:
Tryptophan Operon.
1.It consists of five genes coding for five enzymes catalyzing the synthesis of tryptophan and thus constitute an anabolic pathway.
2.The structure of the operon is more or less similar to that the Lac-Operon & control of the regulator gene (R), promoter gene, operator gene & the structural gene.
3.Here the regulator gene (R) product produces protein which by itself unable to operate. This is referred to as apo-repressor.
4.In presence of tryptophan (co –repressor) the functional repressor is formed that now binds to the operator, preventing the transcription of the operon & production of tryptophan.
2.Difference between Repetitive DNA & Satellite DNA
Answer:
Repetitive DNA
Satellite DNA
Repetitive DNA is a small stretch of DNA repeated many times. They comprise transposable sequences of about 300 nucleotides, which are individually repeated and inserted throughout the chromosome, making up about 5% of the mass.
These are tandem repeats of a simple DNA sequence, which form minor ‘peaks’ after DNA fragmentation and density Gradient Centrifugation. These sequences normally do not code for any protein. It has proved a useful genetic in DNA finger printing.
Chapter : 7
Evolution
Main Terms:
1.Big Bang Theory: According to this theory, the whole matter in the beginning in the universe was concentrated in the form of a dense hot fireball and the universe arose from a huge explosion of a very large entity. Each was formed about 4.5 million years back.
2.Biogeography: It is the study of distribution of plants and animals in different parts of earth.
3.Coacervates: Covacervates are an aggregate of spherical molecules bounded by liquid covering and divide by budding.
4.Adaptive Radiation: It is the process of different species in a given geographical area starting from a point and radiating to the other areas of geography.
5.Natural Selection: The process of selection of the individuals which are well adapted to the changed environmental condition.
6.Saltation: Origin of new species through mutation in a single step.
7.Genetic Drift: It is the change in the gene frequencies of a population which is purely as a matter of chance.
8.Founder Effect: Change in the phenotype and genotype of the progeny of original drifted population (due to drastic changes in allele frequency).
9.Divergent Evolution: Development of organs in different groups of organisms along different directions due to adaptation to different needs. e.g.
a.Homologous Organs such as forelimbs of cattle and human.
b.Thorns and tendrils of Bougainvillea and Cucurbits.
10.Convergent Evolutions: Development of organs in different groups of organisms for the same function due to their common adaptive needs. E.g.
a.Analogous organs such as wings of bats and grasshoppers.
b.Tendril of Pea (Modified Leaf) and tendril of grape vine (modified stem).
11.Mimicry: Resemblance of an organism with another on with a non-living object in form colour pattern and behavior to escape notice by predator or prey. The organism that bears resemblance is called a mimic, and the organism or inanimate object to which a mimic resembles is termed model. E.g. Leaf Insect, Stick Insect.
Oparin-Haldane Theory of Origin of Life:
The experiment of Miller & Urey:
Urey and Miller (1953) demonstrated that the electrical discharges are heat energy can form the complex organic substances from the mixture of Methane, Ammonia, Water, and Hydrogen. They took glass tubes, flasks, condensers, etc., for their experiment. They created an atmosphere containing Hydrogen, Ammonia Methane and water vapour in one flask and allowed the condensed water in another flask and condenser. They passed the electric sparks from electrodes in the gaseous chamber of flask and heated the another flask containing water. They passed the mixture of these gases through the condenser. After a week, they analyzed the liquid for chemical composition inside the apparatus. They found large number of complex organic compounds such as Acetic Acid, Urea, Fatty Acids and Lactic Acid including Amino Acid like glycine, alanine, and aspartic acid. So they called this process of abiotic synthesis. Other investigators added sugar, purines, and pyrimidines to the list of spontaneously formed chemicals by using UV-light and they found fairly complex building bricks of which living matter is composed of.
Hardy-Weinberg Principles:
Hardy-Weinberg principles states:
(i)Allele frequencies in a population are stable and is constant from generation to generation.
(ii)The gene pool (total genes and their alleles in a population) remain" constant. This is called genetic equilibrium.
(iii)Sum total of all the allelic frequencies is 1. For example, in a diploid individual, p and q represent the frequency of allele A and allele a. The frequency of AA individuals in a population is simply p2. Similarly, the frequency of aa is q2 and of Aa is 2pq. Hence, p2 + 2pq + q2 = 1. Thus is a binomial expansion of (p + q )2.
When frequency, measured, differs from expected values, the difference (direction) indicates the extent of evolutionary change. Disturbance in genetic equilibrium or Hardy Weinberg equilibrium i.e. change of frequency of alleles in a population would then be interpreted as resulting in evolution.
Different effects of Natural selection on Variation:
Nature selection is the different reproduction leading to differential contribution of genotypes to the gene pool of the next generation.
The three different effects of natural selection on variation are----
i)If both the smallest and largest individuals contribute relatively fewer offspring to the next generation than those closer to the average size. Then stabilizing selection is operating. This selection reduces variation but does not change the mean value.
ii)If the individuals at one extreme of the size distribution contribute, then the mean size of individuals in the population will increase. In this case directional selection is operating.
iii)When the natural selection favours individuals at both extremes of the distribution, then disruptive election I operating. Thus two peaks are produced in the distribution of a trait.
Exercise
PART – A: Very Short Answer Questions (VSA – 1 Mark)
1.Give the three factors of the modern concept of Evolution.
Ans: Genetic variation, Natural Selection & Isolation
2.What is the significance of Lederberg experiment?
Ans: It demonstrates that the existing gene mutation is the basis of adaptation.
3.What is the theory of spontaneous generation?
Ans: The theory explains the origin of living organisms from decay in matter, like straw, mud, etc.
4.Who discovered mutation and name for the plant he worked on?
Ans: Hugo de Vries on evening primrose plant.
5.Which of the followings are Homologous organs?
a)Thorn of Bougainvillea & Tendrils of Cucurbits
b)Forelimbs of Horse & Cattle.
c)Flippers of Penguins and Dolphins
Ans: Both a) & b)
6.Define recapitulation theory in 3 words.
Ans: Ontogeny repeats phylogeny.
7.Give an example of missing links.
Ans: Archaeopteryx
PART – B: Short Answer Questions (SA – 2 Mark)
1.What is homoeostasis?
Ans: Maintenance of constant internal conditions by organisms for survival. This is achieved by regulating metabolic processes.
2.“Archaeopteryx is considered as a connecting link between reptiles & birds.” Justify the statement by giving two characters of each.
Ans. Archaeopteryx has feathers; rounded cranium and beak like birds, and has teeth, long tail, and free fingers like reptiles.
3.What is genetic drift?
Ans: The elimination of the genes of certain traits when a section of a population migrates or dies natural calamity. It alters the gene frequency of the remaining population.
4.Explain the statement “Natural selection really means differential reproduction.”
Ans: some members of a population have traits (genes) which enable them to grow up and reproduce at a higher rate and leave more surviving offspring in the next generation than others.
5.What is mean by analogous organs? Give an example.
Ans: Organs of different groups of organisms performing the similar function though having different structure. E.g. Tubers of Sweet Potato & Potato.
PART – C: Short Answer Questions (SA – 3 Mark)
1.Why the population of light peppered moth was replaced by black moth variety during Industrializations in England. Explain the mechanism involved.
Ans: During post Industrialization period, the tree trunks became dark due to deposition of industrial smoke and soot. Under this condition the white winged moth could not survive due to predators, but dark winged moth survived as they got selective advantage over white winged moth and thus selected by nature. This shows that those that can better adapt survive and increase in population size.
2.What is adaptive radiation? Describe its two examples.
Ans: The process of evolution of different species in a given geographical area starting from a point and radiating to other geographical areas is called adaptive radiation.
E.g. 1) Australian marsupials, a number of marsupials, each different from others evolved from a common ancestor, but all within the Australian island continent.
2) Darwin's finches (small black birds) in the Galapagos Islands. All the varieties evolved on the island, with varieties of beaks depending on their food habits.
PART – D: Long Answer Questions (LA – 5 Mark)
1.What is genetic equilibrium? Describe the factors that affect Hardy Weinberg Principle.
Ans: Under certain conditions of stability, the allele frequencies of a population are stable and remain constant from generation to generation. This stability is called Genetic equilibrium or Hardy Weinberg principle. Five factors affecting it are:
I)Gene migration-Moving away and coming in of the individuals of a population cause gene frequency.
II)Genetic Drift-Changes in the allele frequencies of a population occurring only by chance.
III)Mutation-Genetic variation due to mutations can create a new species.
IV)Recombination-New combinations of genes due to crossing over in meiosis during gametogenesis.
V)Natural Selection- It promotes adaptation as a product of evolution.
2.What are the two key concepts of Darwinian Theory of evolution? Explain. How Darwinian variation concepts differ from Hugo de Vries mutation idea about evolution.
Ans: The two key concepts of evolution are Branching Descent and Natural Selection. According to Darwin -Any population has built in variation in characteristics. Individuals with those characteristics can survive better in the natural conditions would out numbers the others Such fit individuals produce more progeny. They are selected by nature to survive. In the due course of time new life forms evolve:
DARWINIAN VARIATION
HUGO DE VERIES MUTATION
1. Variations are built in characteristics in a population.
1. Mutation occurs suddenly in a population
2. Heritable variations cause evolution.
2. Mutation causes evolution.
3. Variation is small and directional.
3. Mutations are random and direction less.
4. Evolution through variation is a gradual process.
4. Evolution through saltation.
3. Trace the evolution of man from the first man like hominid.
Ans:
Ramapithecus – It was man like. Few fossils were discovered in Ethiopia and Tanzania.
Australopithecus – They in East African grasslands. They hunted with stone weapons but ate
fruits.
Homo habilis – It was the first human being like creature. Brain capacity was between 650 –
800c.c.
Homo erectus – Fossils were found in Java. It had the brain capacity of about 900c.c.
Homo sapiens – Fossils found in Africa and Asia.
Modem Homo sapiens – Modem man, aroused between 75,000-10,000 years ago. They spread
all over the globe and learned to cultivate plants and domesticate
animals. Agriculture started around 10,000 years ago
UNIT VIII
BIOLOGY IN HUMAN WELFARE
CHAPTER-8
HUMAN HEALTH AND DISEASE
Health: - A state of complete physical, mental and social well being.
Disease: - Any function of physical change from the normal state that causes discomfort or impairs the health of a living organism is called a disease.
Common diseases in Human: -
(i)Communicable (infectious) Diseases: - These diseases are caused by pathogens such as viruses, bacteria, fungi, protozoan, flat worms etc.
(ii)Non Communicable (non-infectious) Diseases: - These diseases do not spread to other persons. These are categorized into four types: -
(a) Deficiency Diseases- Ex. Marasmus, beri-beri.
(b)Degenerative diseases- Ex. Heart diseases.
(c)Allergic diseases- Ex. Asthma.
(d)Cancer- It is caused due to uncontrolled growth of certain tissue.
Immunity: - Immunity refers to the resistance of a host to disease causing organisms and their toxic products.
Antigen: - Antigen are the substance which, when introduced into the body stimulate the production of antibodies.
Antibodies: - These are immunoglobulins (Ig) which are produced in response to antigenic stimulation. Antibodies are grouped into five classes namely IgA, IgD, IgE, IgG, IgM. They differ in size, charge, carbohydrate content and amino acid composition.
Structure: - Antibody molecule is made up of 4 peptide chains, of which two are long chains called Heavy or H-Chains and two are Short Chains called light or L-Chain.
Types of Immunity: -
(i)Innate.
(ii)Acquired
Innate Immunity: - It is resistance to infection which an individual possess by virtue of his or her genetic and constitutional make up (at the time of birth).
Types of barriers which prevent the entry of foreign agents into the body, are:
(i)Physical
(ii)Physiological
(iii)Cellular
(iv)Cytokine.
Acquired Immunity: - The resistance that an individual acquires during life. The cells involved are T-lymphocytes and B- lymphocytes.
Active Immunity: - This involves the active functioning of the person’s own immune system leading to the synthesis of antibodies.
Passive Immunity: - There is a transfer of immune products, like antibodies etc. to a recipient in a readymade form.
Ex. ATS.
Lymphoid Organs: - These are the organs where origin and/ or maturation and proliferation of lymphocytes occur.
Primary Lymphoid Organs- Bone marrow, thymus.
Secondary Lymphoid Organs- Spleen, Lymph nodes, tonsils.
Allergy: - Allergy is the hypersensitiveness of a person to some foreign substance coming in contact with or entering the body.
Ex- Hay fever, Asthma.
Auto Immunity:- It is a condition in which structural and functional damage is produced by the action of immunological competent cells against normal component of body.
Ex- Rheumatoid arthritis.
AIDS (Acquired Immuno Deficiency Syndrome) It is a disorder of cell mediated immune system of the body. There is a reduction in the number of helper T-Cells which stimulate antibody production by B-Cells which results in the loss of natural defense against viral infection.
It is caused by HIV, which is a retrovirus.
It can be diagnosed by ELISA test.
Cancer: - Cancer is an abnormal and uncontrolled division of cells that invade and destroy surrounding tissue.
Types of tumors: -(i) Benign- (Non Cancerous)
(ii) Malignant-(Cancerous)
Causes: - Chemical or Physical agents that can cause cancer are called Carcinogens.
Treatment:-
1. Surgery
2. Radiation Therapy
3. Chemotherapy
4. Immunotherapy.
Drug abuse: -When drugs are taken for a purpose other than their normal clinical use in an amount or concentration that impairs one’s physical, physiological and physiological function, it is said to be drug abuse.
The drugs which are commonly abused are opoids, cannabiniods, stimulants, sedative, LSD, Coca alkaloids.
Opoids are obtained from Papaver somniferum (Poppy plant). Opium is dried later of unripe capsular fruit of poppy. Cannabinoid (natural) is obtained from leaves and inflorescence of cannabis sativa.
Addiction: - The state of physiological and physiological dependence due to prolonged use of drugs or alcohol.
1 Mark Questions
Q1. What is meant by metastasis?
Ans: Spreading of cancer cells to distant site in the body to start new tumors there. This property is called metastasis.
Q2. What are interferons?
Ans: Interferons are antiviral proteins released outside the virus infected cells which protect other cells from infection.
Q3. How does salvia act in body defense?
Ans: Bicarbonate ______ in salvia neutralize the acid in food.
Q4. Which type of immune response is responsible for graft rejection?
Ans: Cell mediated immune response.
Q5. Name two plants that have hallucinogenic properties.
Ans: Atropa belladonna and Datura.
2 Marks Questions
Q1. Which kind of immunity is produced by vaccination? Name the disease against which protection is provided by BCG vaccine?
Ans: Active immunity is produced by vaccination. The vaccine BCG provides protection against tuberculosis.
Q2. Name the cells that produce antibodies? Explain the main function of these compounds?
Ans: Antibodies are produced by B lymphocytes. Antibodies are immunoglobulins (Igs) which are produced in response to antigenic stimulation. They direct the antibody-mediated immunity.
Q3. Write the full form of ELISA. Give an example of the clinical application of ELISA test.
Ans: Enzyme Linked Immuno Sorbent Assay. AIDS can be diagnosed by ELISA test.
3 Marks Questions
Q1. Differentiate between active immunity and passive immunity. Give any one example where passive immunization is needed.
Ans Active Immunity Passive Immunity
(i)It is developed when the person’s own (i) It is developed when antibodies
cells produce antibodies in response to produced in other organisms are
infection or vaccine. injected into a person to counteract
antigen such as snake venom
(ii)It provides relief only after long period. (ii) It provides immediate relief.
(iii)It has no side effects. (iii) It may cause reaction.
(iv)It is long lasting. (iv) It is not long lasting.
Q2. Draw a label diagram of an antibody molecule.
5 Marks Questions
Q1. Describe the life cycle of plasmodium.
Q2. Describe the mechanism by which the AIDS virus causes deficiency of immune system of the infected person.
Q3. Where are B cells ant T cells produced in the human body? How do they differ from each other? Mention only two differences.
CHAPTER-9
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
Animal Husbandry: - Animal husbandry is the agricultural practice of breeding and raising livestock. It deals with feeding, breeding and health care of common domestic animal.
Animal breeding: - Main Objectives:
1.Increased production of milk, meat, egg, wool, etc.
2.Superior quality of milk, meat, egg, wool, etc.
3.Improved resistance to various diseases.
4.Increased productive life.
Methods of animal breeding:-
1.Inbreeding and
2.Outbreeding.
Inbreeding:- When breeding is between animal of same breeds for four to six generations, it is called Inbreeding.
Inbreeding depression: - Continued in breeding reduces fertility and productivity it is called Inbreeding depression.
Outbreeding: - It is breeding between unrelated animals. It is of following types:
1.Out crossing
2.Cross breeding
3.Inter specific hybridization.
Controlled breeding experiment: -
1.Artificial insemination.
2.Multiple Ovulation Embryo Transfer (MOET).
Apiculture: - Rearing of honey bees for the production of honey and bee wax is known as Apiculture.
Common species of honey bees.
1.Apis indica
2.A. mellifera
3.A. dorsata
4.A. florae
Fisheries: - Fisheries is an industry related to catching, processing or selling of fish, shell fish or other aquatic animals. It is also known as piscicultre.
Plant breeding: - plant breeding is the genetic improvement of the crops in order to create plants with desired characters i.e. high yield and disease resistant.
Main steps of breeding: -
1.Collection of variability.
2.Selection of parents.
3.Cross hybridization among selected parents.
4.Selection and testing of superior recombinants.
5.Testing, release and commercialization of new cultivars.
Mutation breeding: -
It is the process by which genetic variations are created through changes in the base sequence within genes.
Tissue culture: -
It is the technique of maintaining and growing plant cells, tissues or organs on artificial medium under controlled environmental conditions.
Explants: -
Any part of the plant taken out and grown in a test tube, under sterile condition in special nutrient media.
Totipotentcy: -
The capacity to generate whole plant from any cell or explant is called totipotentcy.
Somaclonal variation: -
Genetic variation present among plant cells during tissue culture is called Somaclonal variations.
Single cell protein (SCP): - The cell from micro organism like algae, bacteria and yeast and certain fungus are treated in various ways and used as food called single cell protein.
Somatic hybridization: - When hybrid is produced by fusion of somatic cells of two varieties or species, it is known as somatic hybrid and the process is known as Somatic hybridization.
1 Marks questions
Q1. Mention four essential methods for livestock improvement.
Ans: These are breeding, weeding, feeding and heeding.
Q2. Name some edible marine fishes.
Ans: Sardines, Pomfrets.
Q3. Name four important species of honey bees.
Ans: Apis mellifera, A. indica, A. dorsata, A. florae.
Q4. What are the two main methods of animal breeding?
Ans: Inbreeding and Outbreeding.
Q5. Name the alkaloid that prevents the formation of spindle apparatus during mitosis.
Ans: Colchicine.
2 Marks Questions
Q1. How are fishes helpful in controlling diseases? Give example.
Ans:Diseases like malaria, yellow fever and other dreadful diseases that are spread through mosquitoes can be controlled by larvivorous fish.
Ex: Gambusia, Trichogaster, Panchax etc.
Q2. What are the objectives of breeding for improving nutritional quality?
Ans: Objectives are:-
1.Protein content and quality.
2. Oil content and quality.
3. Vitamin content.
4. Micro nutrient and mineral content.
3 Marks Questions
Q1. Define in breeding. What is the danger of inbreeding?
Ans: Inbreeding is defined as the breeding between the animals of same breed for 4-6 generations. Continued breeding reduces fertility and even productivity. This is called inbreeding depression.
Q2. What are the methods involved in classical plant breeding?
Ans: Classical plant breeding involves crossing or hybridization of pure line followed by artificial selection to produce plants with desirable traits. The various characters or traits are as follows:
1.Increased crop yield and improved quality.
2.Increased tolerance to environmental stresses.
3.Resistance to pathogen.
4.Increased tolerance to insect pests.
5.
Q3. Give example of diseases caused by each of fungi, bacteria and viruses in crop plant.
Ans: Diseases caused by fungi–
1. Red rot of sugarcane 2. Late blight of potato.
Diseases caused by bacteria-
Ex: Black rot of crucifer.
Diseases caused by Virus-
Tobacco mosaic, turnip mosaic.
5 Marks questions
Q1. What is Somatic hybridization? Explain the various steps involved in the process. Mention any two uses.
Q2. What is meant by outbreeding? Describe different methods of Outbreeding in animals.
Q3. Discuss the role of micro-organisms in sewage treatments.
CHAPTER- 10
MICROBES IN HUMAN WELFARE
Microbes- These are organisms which cannot be seen by naked eyes. Microbes are diverse microscopic organisms.
They are present in air, water, soil, inside the living organism i.e. plants and animals.
Major groups of Micro organisms- Bacteria, fungi, protozoan, virus, viroids and certain algae.
Microbes in household products: - Curd is produced by lactobacillus and other lactic acid bacteria (LAB) which grow on milk and convert into curd.
The products and the microbial agents are as follows:
a)Diary products----- curd, cheese (Lactobacillus, LAB)
b)Bread---------------- Saccharomyces (Baker’s Yeast)
c)Dosa, idli----------- Leuconostoc, streptococcus.
d)Toddy-------------- Yeast
e)Roquefort cheese—Propionibacterium.
Microbes in Industrial products: - In industries microbes are employed to produced
a)Beverages- Yeast is used to ferment fruit juices and cereals to form ethanol.
b)Antibiotics- Antibiotics are used to kill microbes causing diseases. They are obtained from penicillium and staphylococci.
c)Chemicals, Enzymes, and Bioactive molecules:
a) Organic acids:
i) Acetic acid- Acetobacter aceti.
ii) Citric acid- Aspergillus niger, mucor.
iii) Lactic acid- Streptococcus lactis.
iv) Ethanol- Saccharomyces cerevisiae
v) Butyric acid- Clostridium butylicum
b)Enzymes:
i) Pectinase and protease- These are used to clear fruit juices during bottling.
ii) Streptokinase- Used as clot buster in medical science.
c)Bio active Molecules-
i) Cyclosporin A- (Fungal product) Immuno suppressive agent
ii) Statins- Used as lower blood cholesterol
Microbes in sewage treatment: -
There are two stages:
Primary treatment: - It involves removal of floating and suspended solids from sewage through filtration and sedimentation.
Secondary Treatment: - Primary effluent is taken to aeration taken where a large number of heterotrophic microbes digest a lot of organic matter. This reduces BOD of the effluent.
Microbes in Biogas production: -
Biogas contains methane (60%), carbon dioxide (30-40%).
Methanogens act on cellulosic compound and produce large quantity of methane and carbon dioxide.
Microbes as Bio control agents: - It is the use of biological methods to control plant diseases and pest.
Ex. Bacillus thuringiensis-whose spores are toxic to certain insect larvae but not harmful for other insects.
The toxin producing genes of this bacterium are transferred into resistant to insect pests.
Bt-cotton is an example.
Microbes as Biofertilizers: - Biofertilizers are micro-organisms which bring about nutrient enrichment of soil. Three groups of microbes used as Biofertilizers.
a) Bacteria-Rhizobium, Azotobacter
b) Cyanobacteria-Anabaena, Nostoc
c) Mycorrhiza-Glomus with roots of higher plants.
1 Marks Question
Q1 Write down the scientific name of bakers yeast.
Ans: Saccharomyces cerevisiae
Q2. What is the medical use of cyclosporin A
Ans: It is used as an immunosuppressive agent in organ- transplant patient.
Q3. What is the use of streptokinase?
Ans: It acts as ‘Clot buster’ inside the blood vessel.
Q4. Expand the term LAB.
Ans: Lactic Acid Bacteria.
Q5. Name a cyanobacteria used as human food.
Ans: Spirulina
2 Marks Question
Q1 What is mycorrhiza? How does it help as biofertilizer?
Ans: Mycorrhiza is an association between the roots of a higher plant with a fungus. These fungus help in absorption of phosphorus and produce growth promoting substance. They also protect the plant from the soil pathogen.
Q2. What is BOD? What does it mean if a water sample has more BOD?
Ans: Biochemical oxygen demand represents the amount of dissolved oxygen that would be consumed if all organic matter in one litre of water were oxidized by microorganisms. More value of BOD means the water sample is polluted by organic matter.
Q3. Name the microbial sources of bioactive molecules cyclosporine A and Statin.
Ans: (i) Cyclosporin A- Trichoderma polysporum
(ii) Statin-Monoascus purpureus
3 Marks Question
Q1. Explain the use of Bacillus thuringiensis as a biological control agent.
Q2. Describe the importance of mycorrhiza a biofertilizer.
Q3. What are biopesticides? Give the scientific name and the use of the first
commercially used in the world.
5 Marks Questions
Q1. Name the major enzymes used in industry and explain their importance.
Q2. What is sustainable agriculture? Explain the contribution of biopesticides and
biofertilizer in sustainable agriculture.
Q3. Discuss the role of micro-organisms in sewage treatment.
UNIT IX
BIOTECHNOLOGY
Chapter 11
BIOTECHNOLOGY: PRINCIPLES AND PROCESSES.
Biotechnology:
“Biotechnology deals with the techniques of using live organisms or enzymes from organisms to produce products and processes useful to humans.” For example- making curd, bread or wine are produced by the action of microbes, could also be considered as a form of biotechnology. But in modern sense it is mainly referred to those processes & products in which genetically modified organisms are used.
The European Federation of Biotechnology (EFB) has given definition of biotechnology by combining traditional and modern view. The definition given by EFB is as.
“The integration of natural science and organisms, cells, parts there of and molecular analogues for products and services.”
Principles of Biotechnology:
The following two core techniques that enabled the birth of modern biotechnology are.
i. Genetic Engineering:
Technique to change the chemistry of genetic material (DNA and RNA), to introduce these into hosts organisms and so change the phenotype of the host.
ii. Maintenance of sterile conditions during genetic engineering so that only desired microbes or eukaryotic cells can grow for manufacture of products like antibiotics, Vaccines, Enzymes etc.
Development of Principles of Genetic Engineering:
Hybridization is the traditional method used in plant breeding and animal breeding for the improvement of the products. Very often it leads to the combination of undesired genes with desired genes. Recombinant DNA can be developed by genetic engineering to over come the limitation of hybridization.
Recombinant DNA:- The host DNA combined with foreign DNA or artificial DNA is called as recombinant DNA.
Origin of replication:- The sequences in DNA which are essential for the initiation of Replication are called as the origin of replication.
Cloning:-
The alien DNA is linked with the origin of replication so the DNA can replicate and multiply in the host organism. This is called as DNA cloning.
Construction of 1st Artificial recombinant DNA:
This was done by Stanley Cohen and Herbert Boyer in 1972.
* Plasmids are extra chromosomal DNA which can transfer the genes or DNA one bacteria to another.
* They isolated the antibiotic resistance gene from the plasmid of Salmonella typhimuruim by cutting with restriction enzymes.
* The isolated gene was linked to the plasmid by DNA ligase enzyme. This makes the recombinant DNA in vitro (i.e. in laboratory conditions).
* This recombinant DNA was transferred to the bacteria Escherichia Coli closely related to Salmonella.
* The antibiotic resistant gene can replicate in the E-Coli and multiple copies are formed. This is called as gene cloning.
Three basis steps in Genetically modifying an organism:
i. Identification of DNA with desired genes.
ii. Introduction of the identified DNA into the host.
iii. Maintaining the introduced DNA in host and transfer of the DNA to its progeny.
Tools of Recombinant DNA Technology:
Following tools are required for recombinant DNA technology.
1. Restriction enzymes:-
Restriction enzymes belong to a class of enzymes called as nucleases. These enzymes can cut the DNA double helix at specific sequences. These are of two type- a. Exonucleases b. Endonucleases.
a. Exonucleases:- These enzymes remove nucleotides from the ends of the DNA.
b. Endonucleases: - These make the cuts at specific position with in the DNA. These enzymes recognize specific sequences called palindromic nucleotides sequences in the DNA.
Palindromic nucleotide sequences:- It is the Sequence of the base pairs that reads same on the strands when orientation of reading is kept the same of the following sequences reads same on the two strand in 5’ - 3’ direction or 3’ - 5’ direction.
5’ - GAATTC - 3’.
3’ - CTTAAG - 5’.
The first restriction endonuclease was Hind (II).
Naming of restriction enzymes:
First letter of the name represents of the genus, second letter comes from species of the prokaryotic cell from which they were isolated and Roman number indicated the order. E.g. EcoRI. It is isolated from Eschechia coli R is strain, I- is order of their extraction. Practice Fig11.1for action of EcoRI NCERT Test book page no.196.
Fig. 11.2. Represent recombinant DNA technology NCERT Test book page no. 197.
Separation and isolation of DNA fragments:
The fragments of DNA obtained by the action of restriction enzymes can be separated by the technique known as gel electrophoresis. Since DNA molecules are negatively charged they can move towards anode under electric field through a medium or matrix. The most common matrix is agarose obtained from sea weeds. DNA fragments will separate according to their size through sieving effect provided by the agarose gel hence the smaller the size the farther it moves.
Visualization of DNA fragments:-
The DNA fragments can be stained with ethidium bromide followed by exposure to UV (light) radiations. The bright orange coloured DNA segment will be formed.
Elution:-
The process of extraction of DNA segments from gel is known as elution.
2. Cloning Vectors:- Cloning vectors are the next important tools to restriction enzymes.
Common cloning vectors are plasmids and bacteriophages following features are required to facilitate cloning into a vector.
i. Origin of replication ori: This is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate in the next cells.
ii. Selectable markers:-
In addition to ‘ori’ the vector required a selectable marker which helps in identifying the transformants & non transformants eq. genes encoding resistance to antibiotics such as ampicillin, chloraphenical, tetracycline etc. are used as selectable markers.
Transformation: - It is the process by which a DNA piece is introduced in a host bacterium.
iii. Cloning sites:-
These are the sites at which the foreign DNA is combined. These are generally present in the antibiotic resistant genes.
Practice Fig. 11.4.NCERT Test book page no.199
Insertional Inactivation:-
Selection of recombinants using antibiotic resistance genes is a complex process. There for an alternate method is developed, in this the transforments/ recombinants and non recombinants are identified on the bases of their ability to produce colour in the presence of a substrate. In this a recombinant DNA is inserted in the sequence of the enzyme a-galactosidase. This results in inactivation of the enzyme called as insertional in activation so no blue clours will be given by this type of bacteria. Which indicates the recombination. Non recombinants will give the blue colour.
Vectors for cloning genes in plants and animals:
Some bacteria and viruses can be used as vectors for transforming genes.
For Example- Agrebacterium tumifaciens a pathogen on several dicots deliver a piece of DNA called T- DNA and transform the plant calls into tumor and direct the tumor call to produce the chemical required by pathogen. The Ti- plasmid from this bacterium now can be used to deliver genes of our interest into variety of plants.
In animal retroviruses can deliver their DNA into host calls to transform them into concerned cells. So the retroviruses can be used as vector if the harmful DNA can be replaced by the genes of interest.
3. Competent host:-
DNA being the hydrophilic molecule so to pass it through cell membrane the cells are treated with specific concentration of a divalent cations such as calcium. The recombinant DNA can be forced into such cells by incubating the calls with recombinant DNA on ice followed by placing them briefly at 420c (heat shock) and then putting them back on ice.
The other methods of introduction of alien DNA are microinjection and biolistic or gene gun. In microinjection the DNA is directly injected into the nucleus and in gene gun the cell are bombarded with high velocity micro particles of gold and tungsten coated with DNA.
PROCESSES OF RECOMBINANT DNA TECHNOLOGY:
Recombinant DNA technology involves the following steps- i. Isolation of DNA., ii. Fragmentation of DNA., iii. Isolation of desired DNA fragments., iv.Ligation of DNA fragments into vector., v. Transferring the recombinant DNA into host., vi. Culturing of host cells at large level., vii. Extraction of Desired product.
Let us discuss these steps in some details:-
i. Isolation of Genetic material or DNA:-
This can be done by treating plant and animal cells with enzymes such as lysozyme (bacteria), Cellulase (Plant cell), Chitinase (fungus) RNA can be removed by treatment with ribonuclease. Which proteins can be removed by treatment with protease. DNA is ultimately precipitated and by addition of chilled ethanol.
ii. Cutting of DNA at Specific locations:-
This is done by restriction enzymes. These segments are separated by gel electrophoresis. Vector DNA also treated with same enzymes. The desirable segment of DNA is combined with vector DNA with the ligase enzyme to form recombinant DNA.
3. Amplification of Gene of Interest using PCR:-
PCR stands for polymerase chain Reaction. In this reaction multiple copies of DNA or genes of interest can be synthesized invitro using two sets of primers & DNA polymerase enzyme. In this process 1 billion copies of DNA can be made. Each cycle in polymerase chain Reaction has three steps- i. Denaturation. ii. Primer annealing. iii. Extension of primer.
Practice Fig. 11.6. NCERT Text Book. Page no. 202
A thermo stable DNA polymerase enzyme Taq polymerase is used which is isolated from Thermus aquaticus which remains active at high temperature.
4. Insertion of Recombinant DNA in the host:-
Several methods are used. The recipient cells are made competent to receive the foreign DNA.
5. Obtaining Foreign Gene Products:-
These products are obtained on large scale by using bioreactors where large volumes (100-1000 lips) of culture can be processed. A bioreactor provides the optimum condition for growth (temperature, pH, substrate, salts, vitamins, oxygen. The most commonly used bioreactors are of stirring type which are shown in Fig. 11.7. NCERT Text Book.
A bioreactor has an agitator, an oxygen delivery system, and a form control system, a temperature control system, pH control system and sampling parts so that small volume of the culture can withdrawn periodically.
6. Down stream processing:-
This include Separation, Purification, Quality control testing, Clinical trials of drugs etc.
--------------- x ----------------
Expected Questions:
Very short Answer:-
1. What is Biotechnology?
2. Expand EFB.
3. Write the definition of biotechnology given by EFB.
4. What is recombinant DNA?
5. What is plasmid?
6. What is gene cloning?
7. What is elution?
8. Define transformation.
9. Expand PCR.
10. What are Recombinant proteins?
Short Answer type:-
11. What are the two core techniques which enabled the birth of modern
biotechnology?
12. Explain the formation of 1st Recombinant DNA.
13. Give the three basic steps of genetically modifying an organism.
14. What are restriction enzymes? Explain their type and working.
15. Explain the separation of DNA & isolation of DNA fragments.
16. What are cloning vectors? Give example.
Long Answer:-
17. Explain PCR with suitable diagram.
Chapter-12
BIOTECHNOLOGY AND ITS APPLICATIONS:
As we have discussed in previous chapter the Biotechnology deals with industrial production of biopharmaceuticals and biologicals using genetically modified organisms like microbes, fungi, plants and animals.
The application of Biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatments and energy production.
Three critical research area of Biotechnology are:-
i. Providing best catalysts in the form of improved organisms usually a microbe or pure enzyme.
ii. Creating optimal conditions for the catalyst to work.
iii. Down stream processing technology to purify the proteins/organic compounds.
Let us now discuss uses of Biotechnology in food production and health.
1. Applications of Biotechnology in Agriculture:-
There are three options by which we can increase food production:-
i. By use agro- chemicals in agriculture.
ii. Organic agriculture.
iii. Genetically engineered crop- based agriculture.
Green Revolution increased the food production by three times but yet it is not enough to feed the growing human population. The increased food production was due to improved varieties & agro chemicals. But further increase is not possible by these practices. Use of genetically modified crops is the possible solution.
Genetically Modified Organism:-
Plants, animals, fungi and bacteria whose genes have been altered by manipulation are called genetically modified organisms. There are useful in many ways.
1. Made crops move resistant to abiotic stress.
2. Reduced dependence on chemical pesticides.
3. Helped to reduce post harvest losses.
4. Increased the efficiency to use mineral nutrients.
5. Enhanced nutritional value of food e.g. Vitamin-A enriched rice.
Bt. Cotton:-
Some stains of Bacillus thuringiensis produce proteins that kill certain insects. They produce some toxin insecticidal proteins. These are produced in inactive form protoxins but when insect ingest it is converted into active form due to alkaline pH of the gut which solubilise the crystals. The activated toxin creates pores in the midgut cells cause cell swelling and lysis and eventually cause death.
Specific Bt toxin genes were isolated and incorporated into plant such a cotton. Toxin coding gene is named cry. Such cotton plants are celled Bt cotton. Such crops are pest resistance. Choice of genes depends upon the crop and targeted pest. For example the proteins encoded by the genes cry (I) AC and cry (II) AB controls the cotton bollworms, that of cry (I) AB controls corn borer.
Pest Resistant Plants:-
RNA interference (RNAi) in a process by which the infestation of some parasites can be prevented. This method involves the silencing of a specific mRNA by forming double stranded complementary RNA molecules. The source of complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons).
For Example a nematode Meloidegyne incognitia infects the roots of tobacco plants and cause a great reduction in yield. Using Agrobacterium vectors nematode specific genes were introduced in to the host plants that produced both sense and antisence RNA in the host cells. These two strands form ds RNA (double stranded RNA) and initiated RNAi and thus silenced specific mRNA of nematodes. As a result the parasite could not survive in the transgenic host expressing specific interfering RNA.
2. Applications of Biotechnology in Medicine:-
Biotechnology has made immense impact in the area of health care by production of safe and move effective therapeutic drugs. At present 30 recombinant therapeutics have been approved for human use. In India, 12 of these are presently being marketed.
i. Genetically Engineered Insulin:-
Insulin used for diabetes was extracted from the pancreas of slaughtered cattle and pigs. Some of the patients used to develop allergy. Insulin consists of two short polypeptide chains- chain A and chain B linked together by disulphide bond. In mammals it is synthesized in the form of prohormone containing extra stretch celled the c peptide. It is removed during maturation.
In 1983, Eli Lilly an American company prepared two chains A&B by introducing insulin genes in plasmids of E.coli. Chains A&B were produced separately and combined by disulphide bond to form human insulin.
Practice Fig. 12.3. NCERT text book. Page no.211
ii. Gene Therapy:-
Gene therapy is a collection of methods that allows correction of a gene defect that has been diagnosed in a child/ embryo. In this genes are inserted into a person’s cells and tissues to treat a disease.
The first clinical gene therapy was given in 1990 to a 4- year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. This disorder is caused due to deletion of the gene for adenosine deaminase. This disease can be cured by bone marrow transplantation by enzyme replacement, but these are not completely curative.
As a first step towards gene therapy lymphocytes of the patients are grown in the culture medium. A functional ADAcDNA (using a retroviral vector) is then introduced into these lymphocytes, which were returned to the patient. As lymphocytes are not immortal. So it is not a permanent cure. However if the genes isolated from marrow cells producing ADA is introduced into the host cells at early embryonic stages, it could be a permanent cure.
iii. Molecular Diagnosis:-
Early detection is also possible by the use of biotechnology. Polymerase chain Reaction (PCR) can amplify the DNA and RNA which can help in their early detection.
A single stranded DNA or RNA tagged with radio active molecule (probe) is allowed to hybridize to its complementary DNA and followed by detection with autoradiography to know mutated genes which will not appear in the photographic film.
ELISA is based on antigen antibody interaction. Infections can be detected by presence of antigen or antibodies.
Transgenic Animals:-
Animals with manipulated DNA to posses and express extra (foreign) gene are known as transgenic animals. Over 95% of the transgenic animals are mice.
Let us discuss the common reasons of the production of transgenic animals.
i. Normal physiology and development:-
Transgenic animals are specifically design to study the expression of gene, gene regulation, how genes affect normal functions and development.
ii. Study of Diseases:-
Many transgenic animals are designed to increase our understanding how genes contribute to the development of diseases.
iii. Biological products:-
Transgenic animals can be used to produce the biological products. Such as human protein (x-1-antitrypsin) used to treat emphysema. Similar attempts were made to treat phenyl ketonuria (PKU) and cystic fibrosis.
In 1997 the first transgenic cow Rosie produced human protein enriched milk (2-4 grams/litre). The milk contained the alpha- lactalbumin and was a nutritionally more balanced product for human babies than natural cow milk.
iv. Vaccine Safety:-
Transgenic mice are being used for testing the safety of vaccines before they are used on humans.
v. Chemical Safety testing:-
The transgenic animals are made more sensitive to chemical to know the safety and effects of the toxic chemicals in less time.
Ethical Issues:-
To stop the race of forming transgenic animals some regulations are required. Genetically modified organisms can have unpredictable results when such organisms are introduced into the ecosystem
There fore the Indian govt. has set up organizations such as GEAC (Genetic engineering approved committee) which will make decisions regarding the validity of the GM research.
The problem of patents is also linked to the transgenic. For example the no of varieties of Rice are grown in India. Basmati is one of the varieties with characteristic aroma. In 1997 an American company got the patent rights on Basmati. Same is the case with turmeric and neem also.
Biopiracy:-
It is the term used to refer to the use of bio resources by multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payments.
The Indian parliament has recently cleared the second amendment of the Indian patent Bill, which takes such issues into consideration, including patents terms and emergency provisions.
Abbreviations—PCR-Polymerase Chain Reaction
EFB –European Federation of Biotechnology
Bt – Bacillus thuringiensis
GEAC-Genetic Engineering Approval Committee
--------------------------------------------------------------------------------
Questions
Very short Answer type:-
1. What is green revolution?
2. What are genetically modified organisms (GMO)?
3. What is gene therapy?
4. What are transgenic animals?
5. Name the first transgenic cow?
6. Expand GEAC.
7. What is biopiracy?
Short Answer type:-
8. What are three critical research areas of biotechnology?
9. Give three options by which the food production can be increased.
10. What is Bt. cotton? How it is beneficial?
11. What is RNA interference (RNAi)? Explain how it is used to develop pest resistant plant with example.
12. What is genetically Engineered Insulin? Explain its synthesis.
Long Answer type:-
13. How genetically modified plants are useful than their normal counter parts?
14. Explore some common reasons for Genetic modification of animals.
UNIT X
ECOLOGY
CHAPTER 13
ORGANISMS AND POPULATIONS
Sub Topics:
1 Organisms and Environment
2 Populations
I Organism and environment
ENVIRONMENT: It is sum of all biotic (Living) and abiotic (None living factor that influence an environment.
CLIMATE AND WEATHER: The properties of atmosphere like temperature, Pressure, humidity, rainfall wind etc., at a given place is the average weather of a given area.
BIOME: A large unit characterized by major vegetation type associated with fauna in specific climate e.g. Terrestrial Biomes are desert, temperate, deciduous and tropical rain forest.
HABITAT: It is a specific physical place or locality occupied by an organisms, population or community which has a particular combination of abiotic or environmental factors.
Major Abiotic factors:
a)Temperature: Temperature is the degree of hotness or coldness of a body.
i)Eurythermal – The organisms which can thrive in wide range of Temperature.
ii)Stenothermal – The organisms which are restricted to a narrow range of temperature.
iii)Homeostasis – The process of maintaining a constant internal environment under varying external environment.
b)Water
i)Salinity – The salt concentration of water. It is 5% in Inland water, 30-35% in sea and 100% in hyper saline lagoons.
ii)Euryhaline – The organisms which are tolerant of a wide range of salinities.
iii)Stenohaline – The organisms whose tolerance is restricted to a narrow range of salinities.
c)Light :
Light plays an important role in plants by controlling various processes like Photoperiodism, Photosynthesis etc.
d) Soil:
Soil is uppermost weathered layer of earths crust and is composed of minerals and partly decomposed organic matter. The nature and properties of soil dependent on the climate, weathering process, sedimentation etc.
Response of Abiotic Factors
During the change in environmental conditions , External environment the organism should try to maintain the constancy of internal environment ( Homoeostasis ) .
The possibilities of response may be of the following types.
i)Regulate: The regulation may be Osmoregulation or Thermoregulation. Thermoregulation is maintained by exercise and body size during evolution whereas Osmoregulation is maintained by Kidney.
ii)Conform: Most of the animals can change their internal environment according to external environment. Likewise many organisms have the capacity to change osmotic pressure according to changed osmotic medium of the medium. They are called conformers.
iii)Migrate: It means change of place from one place to another. It involves short as well as long distance migration.
iv)Suspend: I order to overcome the unfavorable condition s, plants undergo a process known as dormancy during which metabolic activities are reduced. Hibernation ( Winter sleeping as well as Aestivation ( Summer sleeping ) is also induced in animals to overcome unfavorable conditions .
ADAPTATIONS
The special abilities of plant and animals that unable them ton survive under existing environmental conditions.
The important adaptive features are as follows
i)Plants of desert poses spines, stems and succulents, some have CAM adaptation .eg Opuntia.
ii)Some animals conserve water by concentrating their urine.
iii)Animals of colder climates undergo hibernation.
iv)Plants of saline environment possess pneumatophores which help in gaseous exchange.
v)
II. POPULATION
Population is defined as a group of individuals of plant or animals inhabiting a given area. The study about population is called demography.
Population attributes:
Population Density - It is the no of species of a individual per unit area or volume . It is calculated as
PD = N / S
Where N = No of Individual
S = No of units in a region
Age Pyramids: This shows the age distribution of male and female sin a combined diagram. This reflects the growth of status of population regarding
a)Whether the population is growing
b)Stable
c)Declining
Population Growth: It can be measured as increase in its size over a period of time by the formula
N t + 1= N t + [ ( B+I ) – ( D+E ) ]
Where N t = Increase in Population size after time t
B = Natality Rate
I = Rate of Immigration
D = Mortality Rate
E = Rate of Emigration
Natality: The increase in no of individual in a population under given environmental condition .
Mortality: The decrease in no of individual in a population under given environmental condition .
Immigration: The no of individual added to the density / habitat of some species.
Emigration: The number of individual lost from the population due to outward migration.
Growth Models: There are two models related to population growth.
i)Exponential Growth Curve: Observed in natural environment with plenty of food but no predators. It shows rapid growth in population which continues till enough food is available.
It is represented by the formula
d N / d t = r N
Where r = Intrinsic rate of Natural increase
N = Population size
d N / d t = Rate of change of population size.
ii) Logistic Growth curve: Observed in environment with limited resources . Here fittest one survives and shows a sigmoid curve which is known as logistic growth. It is represented by the formula
d N / d t = r N ( K – N / K)
Where r = Intrinsic rate of Natural increase
N = Population density at time t
d N / d t = Rate of change of population size
K = Carrying capacity.
Population Interactions: It is of two types
a)Positive Interaction
b)Negative Interaction
i) Predation :It involves the relationship between Predator and Prey.
ii) Competition: The interaction between two species in which both suffers adverse affect is known as competition. It is of two types Inter-specific – Between two different species and Intra specific - within same species
iii ) Parasitism - The interaction between two species in which one suffers adverse affect( host ) whereas the other gets benefit from the other ( Parasite )is known as Parasitism . It is of two types
c)Ectoparasites - e.g. Leeches, Head Louse etc
d)End parasites – e.g. Tapeworm
iv) Commensalisms - Relationship between two species in which one species is benefit but the other is nor benefited nor harmed .e.g. Epiphytes like tree ferns and tree.
v) Mutualism – The relationship both species are benefited from each other.eg.Relationship between Fungus and Algae.
Questions
1 What do you mean by Habitat? 1
2 What do you mean by Biome? 1
3 How hibernation is useful for survival? 1
4 Define adaptations. Describe with few example. 1
5 Differentiate between Euryhaline and Stenohaline organisms. 2
6 Differentiate between Eurythermal and Stenothermal organisms. 2
7 What is Homeostasis .Explain the concept of Regulate and Conformers? 3
8 Describe specific type of adaptation with reference to xerophytes root system
stem and leaves. 3
9 How is mutualism different from commensalisms? Give one example of each. 3
10 Differentiate between J shaped and S Shaped Sigmoid curve with the help of
Graph and equations. Under what condition can J Shaped Sigmoid curve be represented
as S Shaped sigmoid curve ? 5
CHAPTER 14
ECOSYSTEM
1 Ecosystem–Structure and Function
2. Productivity
3 Decomposition
4 Energy Flow
5 Ecological Pyramids
6 Ecological Succession
7 Nutrient Cycling
8 Ecosystem Services
1 ECOSYSTEM – STRUCTURE AND FUNCTION
An ecosystem can be visualized as a functional unit of nature, where living organisms interact among themselves and also with the surrounding physical environment.
The components of the ecosystem are seen
(i) Productivity;
(ii) Decomposition;
(iii) Energy flow; and
(iv) Nutrient cycling.
2. PRODUCTIVITY
The rate of biomass production is called productivity. It is expressed in terms of g–2 yr –1 or (kcal m–2) yr–1
Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight (g –2) or energy (kcal m–2).
Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis.
Net primary productivity (NPP). - Gross primary productivity minus respiration losses (R),
is the net primary productivity (NPP). Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores and decomposers).
GPP – R = NPP
Secondary productivity is defined as the rate of formation of new organic matter by consumers.
3 DECOMPOSITION
Decomposition concerns with break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients.
Detritus -Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute detritus, which is the raw material for decomposition.
Leaching is the process by which water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
Humification leads to accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.
Mineralization.- The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralization.
4 ENERGY FLOW
Except for the deep sea hydro-thermal ecosystem, sun is the only source of energy for all ecosystems on Earth. Of the incident solar radiation less than 50 per cent of it is photo synthetically active radiation (PAR). Plants capture only 2-10 per cent of the PAR.
Producers - Producers are the green plant in the ecosystem. Primary producers in an aquatic ecosystem are various species like phytoplankton, algae and higher plants.
Consumers - All animals depend on plants (directly or indirectly) for their food needs. They are hence called consumers and also heterotrophs. If they feed on the producers, the plants, they are called primary consumers, and if the animals eat other animals which in turn eat the plants (or their produce)They are called secondary consumers.
Herbivores- The primary consumers are herbivores. Eg insects, birds and mammals in terrestrial ecosystem and molluscs in aquatic ecosystem.
Primary carnivores The consumers that feed on these herbivores are carnivores, are called primary carnivores (though secondary consumers.
Decomposers – Organisms which are heterotrophic organisms, mainly fungi and bacteria. They meet their energy and nutrient requirements by degrading dead organic matter or detritus. These are also known as saprotrophs
Food web - The natural interconnection of food chains make it a food web.
Trophic level - Based on the source of their nutrition or food, organisms occupy a specific place in the food chain that is known as their trophic level.
Standing crop -Each trophic level has a certain mass of living material at a particular time called as the standing crop. The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area
A simple grazing food chain (GFC) is depicted below:
Grass Goat Man
(Producer) (Primary Consumer) (Secondary consumer)
5 ECOLOGICAL PYRAMIDS
The graphical representation of number, energy and biomass content in a food chain is called Ecological Pyramid.
Types of Ecological Pyramids:
(a) Pyramid of number;
(b) Pyramid of biomass and
(c) Pyramid of energy.
* Pyramid of energy is always upright, can never be inverted
* Pyramid of Biomass and number are upright in most cases but can be inverted. In case of Tree dominated Pyramid of number are inverted but in deep water body Pyramid of Biomass is inverted
6 ECOLOGICAL SUCCESSION
In all communities the composition and structure constantly change in response to the changing environmental conditions over a period of time and is known as ecological succession.
a)Succession occurring on previously occupied site is called Primary succession
b)Succession occurring on previously unoccupied site is called Secondary succession
Steps or sere of succession :
1 The plants that invade the land initially are called Pioneer Community
2 The entire sequence of communities that successively change in a given area are called sere(s). The individual transitional communities are termed seral stages or seral communities.
3 These changes lead finally to a community that is in near equilibrium with the environment and
that is called a climax community
Types of succession in Plants
Hydrarch succession takes place in wetter areas and the success ional series progress from hydric to the mesic conditions.
Xerarch succession takes place in dry areas and the series progress from xeric to mesic conditions. Hence, both hydrarch and xerach successions lead to medium water conditions (mesic) – neither too dry (xeric) nor too wet (hydroid).
Stages in Xerarch succession
Lichens stage bryophyte stage bigger plants climax forest community
Xerophytic habitat gets converted into a mesophytic.
Stages in Hydrarch succession
Phytoplankton’s free-floating angiosperms rooted hydrophytes sedges grasses trees (forest). With time the water body is converted into land.
In secondary succession since soil is already there, the rate of succession is much faster and hence, climax is also reached more quickly.Primary succession, is a very slow process, taking maybe thousands of years. This change is orderly and sequential, parallel with the changes in the physical environment..
7 NUTRIENT CYCLING
The movement of nutrient elements through the various components of an ecosystem is called nutrient cycling.
Nutrient cycles are of two types:
1 Gaseous Cycle
2 Sedimentary Cycles.
Ecosystem – Carbon Cycle
* Carbon constitutes 49 per cent of dry weight of organisms and is next only to water.
* 71 per cent carbon is found dissolved in oceans.
* About 4 × 1013 kg of carbon is fixed in the biosphere through photosynthesis annually.
* A considerable amount of carbon returns to the atmosphere as CO2 through respiratory activities of
the producers and consumers.
* Human activities have significantly influenced the carbon cycle. Rapid deforestation and massive burning of fossil fuel for energy and transport have significantly increased the rate of release of carbon dioxide into the atmosphere
2 Ecosystem – Phosphorus Cycle
* Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy transfer systems.
* The natural reservoir of phosphorus is rock, which contains phosphorus in the form of phosphates.
* The waste products and the dead organisms are decomposed by phosphate-solublising bacteria
releasing phosphorus.
8 ECOSYSTEM SERVICES
* Healthy ecosystems are the base for a wide range of economic, environmental and aesthetic goods and services. The products of ecosystem processes are named as ecosystem services,
* Healthy forest ecosystems purify air and water, mitigate droughts and floods, cycle nutrients, generate fertile soils, provide wildlife habitat, maintain biodiversity, pollinate crops, provide storage site for carbon and also provide aesthetic, cultural and spiritual values.
* According to Robert Constanza and his colleagues an average price tag of US $ 33 trillion a year on these fundamental ecosystems services, which are largely taken for granted because they are free.
Questions
1 What is meant by the statement that energy flow is unidirectional flow of information? 1
2 What is net primary productivity? 1
3 What is Gross primary productivity of an ecosystem? 1
4 What is Net primary productivity (NPP) of an ecosystem? 1
5 What is photo synthetically active radiation? 1
6 What is Standing crop? 1
7 What does secondary production in the ecosystem indicate? List any two factors by which
the productivity of aquatic ecosystem depends. 2
8 What is Ecological Pyramid. What are the three parameters used for constructing
Ecological Pyramids? 2
9 Explain with the help of example how the pyramid of numbers and the pyramid of Biomass
look inverted. 3
10 Why is secondary succession faster then Primary succession? 3
11 Represent the decomposition cycle in terrestrial ecosystem. 3
12 Explain the different stages of hydrarch succession. How is it different from Xerarch
succession? 5
13 What are bio geo chemical cycles? Explain Phosphorous cycle with the help of schematic
diagram. Why it is called sedentary cycle? 5
CHAPTER 15
BIODIVERSITY ANDCONSERVATION
1 Biodiversity
2 Biodiversity Conservation
Edward Wilson “ Biodiversity is the combined diversity at all the levels of biological organization.”
Types of Biodiversity
(i)Genetic diversity : Diversity of Genes in a species
A single species might show high diversity at the genetic level over its distributional range.
India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango.
(ii)Species diversity: The diversity at the species level.
The Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
(iii) Ecological diversity: Diversity at the ecosystem level,
- India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows have greater ecosystem diversity than a Scandinavian country like Norway.
Species on Earth and in India
According to the IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million. Robert May places the global species diversity at about 7 million.
More than 70 per cent of all the species recorded are animals, while plants (including algae,
Fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total. Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total.
Although India has only 2.4 per cent of the world’s land area, its share of the global species diversity is an impressive 8.1 per cent.
India is one of the 12 mega diversity countries of the world. Nearly 45,000 species of plants and twice as many of animals have been recorded from India.
2 Patterns of Biodiversity
(i)Latitudinal gradients: The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution.
Tropics (latitudinal range of 23.5° N to 23.5° S) harbor more species than temperate or polar areas.
Ecologists and evolutionary biologists have proposed various hypotheses;
(a) Speciation -A function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification,
(b) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant
and predictable. Such constant environments promote niche specialization and lead to a
greater species diversity and
(c) There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.
(iii)Species-Area relationships:
German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit.
On a logarithmic scale, the relationship is a straight line described by the equation
log S = log C + Z log A
where S= Species richness A= Area
Z = slope of the line (regression coefficient)
C = Y-intercept
Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region
But the species-area relationships among very large areas like the entire continents, you will find that the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2).
3 The importance of Species Diversity to the Ecosystem
- Communities with more species are more stable then with less species.
- Source of food and improved varieties.
- Ecosystem services.
- Aesthetic and cultural benefits.
4 Loss of Biodiversity
-The IUCN Red List (2004) documents the extinction of 784 species (including 338
vertebrates, 359 invertebrates and 87 plants) in the last 500 years.
- The current species extinction rates are estimated to be 100 to 1,000 times faster than in the
pre-human times.
- Examples of recent extinctions include the Dodo (Mauritius), Quagga (Africa), Thylacine
(Australia), Steller’s Sea Cow (Russia) and three sub species (Bali, Javan, Caspian) of tiger
Effect of loss of biodiversity in a region may lead to
(a) Decline in plant production,
b) Lowered resistance to environmental perturbations such as drought and
(c) Increased variability in certain ecosystem processes such as plant productivity, water use,
and pest and disease cycles.
Causes of biodiversity losses:
The accelerated rates of species extinctions that the world is facing now are largely due to human
activities. There are four major causes (‘The Evil Quartet’ is the sobriquet used to describe them).
i) Habitat loss and fragmentation
(ii) Over-exploitation:
(iii) Alien species invasions:
(iv) Co-extinctions:
II BIODIVERSITY CONSERVATION
1 Why Should We Conserve Biodiversity?
Reasons
1 Narrowly utilitarian argument for conserving biodiversity are obvious; humans derive countless direct economic benefits from nature food, firewood, fiber, construction material, industrial products and products of medicinal importance
2 Broadly utilitarian arguments say that biodiversity plays a major role in many ecosystem services that nature provides.
3 Ethical arguments for conserving biodiversity relates to what we owe to millions of plant, animal and microbe species with whom we share this planet
How do we conserve Biodiversity?
1 In situ conservation-
Conservation in natural environment like by protected areas, Biosphere reserve, Sacred Forest and reserve.
2 Ex situ Conservation– By creating natural habitat I a specified area or inside laboratory condition. By setting up botanical garden, zoos pollen and seed banks, tissue culture, gene banks etc
Questions
1. Name the three important components of biodiversity. 1
2. How do ecologists estimate the total number of species present in the world? 1
3. Give three hypotheses for explaining why tropics show greatest levels of species richness. 2
4. What is the significance of the slope of regression in a species – area relationship? 2
5. What are the major causes of species losses in a geographical region? 3
6. How is biodiversity important for ecosystem functioning? 3
7. What are sacred groves? What is their role in conservation? 3
8. Among the ecosystem services are control of floods and soil erosion. How is this
achieved by the biotic components of the ecosystem? 3
9. The species diversity of plants (22 per cent) is much less than that of animals (72 per
cent). What could be the explanations to how animals achieved greater diversification? 5
10. Can you think of a situation where we deliberately want to make a species extinct? How
would you justify it? 5
CHAPTER 16
ENVIRONMENTAL ISSUES
1 Air Pollution and Its Control
2 Water Pollution and Its Control
3 Solid Wastes
4 Agro-chemicals and their Effects
5 Radioactive Wastes
6 Greenhouse Effect and Global Warming
7 Ozone Depletion in the Stratosphere
8 Degradation by Improper Resource Utilization and Maintenance
9 Deforestation
Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil. Agents that bring about such an undesirable change are called as pollutants.
In order to control environmental pollution, the Government of India has passed the Environment (Protection) Act, 1986 to protect and improve the quality of our environment (air, water
and soil).
1 AIR POLLUTION AND ITS CONTROL
Air pollution is caused by sources:
i)Natural sources- Pollen dust, smoke produced by volcano and forest fire
ii)Man made sources – Factories, electrical power plants, Industrial vehicles etc.
Air pollutants – Types
i)Particulate matter- Solid or liquid droplets present in air
ii)Carbon monoxide – Produced due to incomplete combustion of fuels .
iii)Hydrocarbons – Produced due to burning of fossil fuel and decomposition of organic matter.
Control of Air Pollution
1 Particulate air pollutants are controlled by using arresters, scrubbers, filters, Electrostatic precipitators
2 Gaseous air pollutants can be controlled by absorption and adsorption
3 Automobile exhaust can be controlled by using efficient engines, catalytic converters, improvement
of fossil fuel CNG etc
Some techniques of removing air pollutants:
Electrostatic precipitator
-Electrostatic precipitator can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.
-It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles giving them a net negative charge.
The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough to allow the dust to fall.
Catalytic converters,
- Catalytic converters, have expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into automobiles for reducing emission of poisonous gases.
- The exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively.
- Motor vehicles equipped with catalytic converter should use unleaded petrol because lead in the
Petrol inactivates the catalyst.
1.1 Controlling Vehicular Air Pollution: A Case Study of Delhi
- Delhi ranks fourth among the 41 most polluted cities of the world.
- To reduce pollution the entire fleet of public transport from diesel to compressed natural gas (CNG).
-Benefit of CNG over Petrol and Diesels:
- CNG burns most efficiently, unlike petrol or diesel,
- very little of it is left unburnt.
- CNG is cheaper than petrol or diesel
- Cannot be adulterated like petrol or diesel.
- The Government of India - New auto fuel policy
- Euro II norms, stipulates that sulphur be controlled at 350 parts-per-million (ppm) in diesel and 150 ppm in petrol. Aromatic hydrocarbons are to be contained at 42 per cent of the concerned fuel. It aims to reduce sulphur to 50 ppm in petrol and diesel and bring down the level to 35 per cent.
-The Bharat Stage II (equivalent to Euro-II norms), which is currently in place in11 cities is applicable to all automobiles throughout the country from April1, 2005. All automobiles have met the Euro III emission specifications in these 11 cities from April 1, 2005and have to meet the Euro-IV norms by April 1, 2010. The rest of the country will have Euro-III emission norm compliant automobiles and fuels by 2010.
- Air (Prevention and Control of Pollution) Act came into force in 1981, but was amended in 1987 to include noise as an air pollutant.
2 WATER POLLUTION AND ITS CONTROL
Water Pollution is any undesirable change in physical, chemical or biological characteristics of water.
The Government of India has passed the Water (Prevention and Control of Pollution) Act, 1974 to safeguard our water resources.
1 Domestic Sewage and Industrial Effluents
Composition of waste water is difficult to remove and is the major source of water pollution.
ENVIRONMENTAL ISSUES
Biochemical Oxygen Demand
- It is the amount of organic matter in sewage water by measuring (BOD).
- Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a
lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point
of sewage discharge.
- This causes mortality of fish and other aquatic creatures.
Algal bloom
- Presence of large amounts of nutrients in waters also causes excessive growth of planktonic (free-
floating) algae, called an algal bloom which imparts a distinct colour to the water bodies.
- Algal blooms cause deterioration of the water quality and fish mortality. Some bloom-forming algae
are extremely toxic to human beings and animals.
Biomagnification
- Toxic substances present in industrial waste waters, can undergo biological magnification
(Biomagnification) in the aquatic food chain.
- Biomagnification refers to increase in concentration of the toxicant at successive trophic levels.
- This phenomenon is well-known for mercury and DDT
Cultural or Accelerated Eutrophication
Pollutants from man’s activities like effluents from the industries and homes having nitrates and phosphates can accelerate the aging process of water bodies. This phenomenon has been called Cultural or Accelerated Eutrophication.
Nitrates and phosphates, over stimulate the growth of algae, causing unsightly scum and unpleasant odors, and robbing the water of dissolved oxygen vital to other aquatic life
3 SOLID WASTES
Solid wastes refer to everything that goes out in trash. Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the municipality. The municipal solid wastes generally comprise paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.
Sanitary landfills were adopted as the substitute for open-burning dump but danger of seepage of chemicals, etc., from these landfills polluting the underground water resources
Solid wastes category:
(a) bio-degradable,
(b) recyclable and
(c) the non-biodegradable.
E-wastes
- Irreparable computers and other electronic goods are known as electronic wastes (e-wastes). E-wastes are buried in landfills or incinerated.
4 AGRO-CHEMICALS AND THEIR EFFECTS
Due to green revolution, use of inorganic fertilizers, pesticides herbicides, fungicides has increased for enhancing crop production causing serious agro chemical pollution .
5 RADIOACTIVE WASTES POLLUTION
- Radiation, that is given off by nuclear waste causes mutations and in high doses is lethal but at lower doses, it creates cancer and is extremely damaging to biological organisms,
- Storage of nuclear waste should be done in suitably shielded containers buried within the rocks, about 500 m deep below the earth’s surface
6 GREEN-HOUSE EFFECT AND GLOBAL WARMING
- The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of Earth’s
surface and atmosphere
- Clouds and gases reflect about one-fourth of the incoming solar radiation, and absorb some of it but
almost half of incoming solar radiation falls on Earth’s surface heating it, while a small proportion is
reflected back.
- Earth’s surface re-emits heat in the form of infrared radiation but part of this does not escape into
space as atmospheric gases (e.g., carbon dioxide, methane, etc.) absorb a major fraction of it.
- The molecules of these gases radiate heat energy, and heat up Earth’s surface.
- During the past century, the temperature of Earth has increased by 0.6oC .
7 OZONE DEPLETION IN THE STRATOSPHERE
- Ozone is found in the upper part of the atmosphere called the stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun.
- UV rays are highly injurious to living organisms since DNA and proteins of living organisms preferentially absorb UV rays, and its high energy breaks the chemical bonds within these molecules.
- The thickness of the ozone in is measured in terms of Dobson units (DU).
- Ozone is degraded by chlorofluorocarbons (CFCs) used as refrigerants.
- Ozone depletion is occurring widely in the stratosphere particularly marked over the Antarctic region called ozone hole
- UV-B damages DNA and mutation may occur. It causes aging of skin, damage to skin cells and various types of skin cancers.
- In human eye a high dose of UV-B causes inflammation of cornea, called snow-blindness cataract, etc.
- Montreal Protocol, was signed at Montreal (Canada) in 1987 (effective in 1989) to control the emission of ozone depleting substances.
8 DEGRADATION BY IMPROPER RESOURCE UTILISATION AND MAINTENANCE
Natural resources are degraded by.
- Soil erosion and desertification: The development of the fertile top-soil takes centuries. When large barren patches extend and meet over time, a desert is created..
- Water logging and soil salinity: Irrigation without proper drainage of water leads to water logging in the soil that draws salt as a thin crust on the land surface or starts collecting at the roots of the plants. This increased salt content affects the growth of crops and is extremely damaging to agriculture.
9 DEFORESTATION
- Deforestation is the conversion of forested areas to non-forested ones.
- 40 per cent forests have been lost in the tropics, compared to only 1 per cent in the temperate region.
- National Forest Policy (1988) of India has recommended 33 per cent forest cover for the plains and 67
percent for the hills.
Causes of Deforestation
1Expansion of Agriculture
2Urbanization
3Industrialization
4Excessive commercial use of Forest products
5Overgrazing by cattle
Effects of Deforestation
1 Increased soil erosion
2 Desertification
3 Extinction of Plants and animals
4 Global Warming
5Threat to indigenous peoples
Jhum cultivation : Slash and burn agriculture, commonly called as Jhum cultivation is practiced in in the north-eastern states of India
Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past. Reforestation may occur naturally in a deforested area.
People’s Participation in Conservation of Forests
- The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting wildlife.
Chipko Movement of Garhwal Himalayas.
- In 1974, local women showed enormous bravery in protecting trees from the axe of contractors by hugging them.
- The Government of India in 1980s has introduced the concept of Joint Forest Management (JFM) so as to work closely with the local communities for protecting and managing forests.
Questions
Q.1) Name the unit for measuring the thickness of ozone layer. 1
Q.2) What steps were taken in Delhi to control vehicular air pollution? 1
Q.3) what are the various sources of waste water? What is the composition of waste water? 1
Q.4) Improper disposal of sewage may result in the outbreak of various diseases. Name a few 1
of these diseases. 1
Q.5) what was the cause for the decline in the population of Bald Eagles in the mid-twenty
century in USA? 2
Q.6) What is cultural eutrophication? 2
Q.7) What are the effects of release of thermal waste waters into the natural water bodies? 2
Q.8) Give an example of integrated approach to waste water treatment. 2
Q.9) Why is unleaded petrol being used? 2
Q.10) Discuss the role of women and communities in protection and conservation of forests. 3
Q.11). Why ozone hole forms over Antarctica? How will enhanced ultraviolet radiation affect us? 3
Q 12) Write critical notes on the following:
a) Catalytic converter (b) Particulate matter (c) Electrostatic precipitator 3
Q 13) What is BOD? What is its significance ? With the help of suitable graph show the
relationship between BOD and dissolved oxygen. How can BOD be decreased in a
water body? 5
Q 14) What is meant by Ozone shield? How is ozone shield depleted? What are the effects of
ozone shield depletion on Plants and Human beings ? 5
-x-
Model Question Paper -I
Class XII Biology
Time: 3 Hours Max. Marks : 70
General Instructions:
1. All questions are compulsory.
2. The question paper consists of four sections A, B, C and D. Section-A contains 8 questions of 1 mark each, Section B is of 10 questions of 2 marks each, Section C has 9 questions of 3 marks each whereas Section D is of 3 questions of 5 marks each.
3. There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and all the three questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions.
4. Wherever necessary, the diagrams drawn should be neat and properly labeled.
Section A
1. What would happen if corpus luteum is not degenerated? 1
2. “Cleistogamous flowers are invariably autogamous” Justify 1
3. What is the Non coding sequences present within a gene called? 1
4. Which DNA sequences would a Restriction enzyme Eco RI recognize and cut? 1
5 .What are the conditions of the earth atmosphere conducive for the origin of life? 1
6. Name the dominant producers in a deep aquatic ecosystem. What other name could
you give to a primary consumer ? 1
7 What is the starting point of a detritus food chain? 1
8 How do neutrophils act as cellular barriers to pathogens in Humans? 1
Section B
9 Apomixis mimics sexual reproduction, do you agree? Justify your answer. Also
state how apomixis differs from polyembryony. 2
10 How has biotechnology helped in improving life of Diabetic people? 2
11 Mention the role of histone proteins in packaging of DNA to form the structure of
chromatin fiber. 2
13. Justify that Sickle shaped anemia is a six linked disorder. 2
14 A person injured in road accident and requires immediate immune response was brought to doctor
i) What should the doctors immediately do ?
ii) What kind of immunity was provided to the patient?
iii) Define this kind of immunity. 2
15 Why does the beekeeper keep the beehives in the crop in the flowering seasons?
Mention two advantages. 2
16 Out of Eurythermal and Stenothermal animal which will survive the global
increase in temperature? Justify your answer. 2
17 Given below is a pedigree chart. Mention if the trait is autosomal dominant autosomal recessive or sex linked.
18 If the chromosome no in a plant species is 20, what will be the chromosome number and
the ploidy of the i) Microspore mother cell ii) the endosperm cells? 2
Section c
19 Fill in the gaps in the following table showing certain terms and meanings: 3
Terms
Meanings
I
Ii
Iii
Iv
V
vi
………………………….
………………………….
Restriction enzymes
Plasmids
Tran genes
…………………………
Non coding sequence of DNA
Techniques used to solve paternity disputes
………………………………………………………………………
………………………………………………………………………
………………………………………………………………………
Nucleotide sequences with a single base differences
20 a) In which part of female reproductive system do the following events occur?
i) Release of 1st Polar body
ii) Release of 1st Polar body
iii)Fertilization
iv)Implantation
b) Name the hormone that the female pituitary release for parturition and what is source of
signal for the same ? 3
21 In the following diagram the two stands are ready for transcription
(2 ) (1)
3` 5`
5` 3`
(3 ) (4)
i) Label parts marked 1 - 4 and state their function sin Transcription
ii) Which DNA strand will take part in making a meaningful copy of RNA . 3
22 How were the various simulation of primitive environment created in the experiment performed by Stanley Miller?
i) Primitive environment on earth
ii) Energy source at the time of origin
iii) Formation of organic molecule of life to prove the theory of chemical evolution . 3
23 What are flocs? State the different role in effluent treatment and their ultimate fate in sewage
treatment tank. 3
24 In bacterial culture some of the colonies produced blue colour in presence of chromagenic
substrate and some did not in the presence of or absence of an insert (rDNA ) in the coding
sequence of galactosidase.
a) Mention the mechanism and the steps involved in the above experiment .
b) How is it advantageous over stimulating plating on two plates having different antibiotics ? 3
25 ‘ A population has been exhibiting genetic equilibrium”
i) Explain the above meaning
ii) Name the underlying principal
iii) List any two factors which will upset the genetic equilibrium of the population . 3
26. Draw the pyramid of energy. 3
27. Diagramatically represent a test cross. 3
SECTION D
28. What are cry proteins? Name the organism that produce it . How has man exploited this
protein for his benefit? Name the cry gene used for control of cotton bollworms and
corn borer. 5
29. What is BOD? What is its significance? With the help of suitable graph show the
relationship between BOD and dissolved oxygen. How can BOD be decreased in a
water body? 5
30. What is ecological succession ? Explain the different stages of hydrarch succession.
How is it different from Xerarch succession? Why is secondary succession faster
then Primary succession? 5
SOLUTIONS
Section A
1 If Corpus luteum is not degenerated then Progesterone secretion continues and helps sustenance
of Pregnancy . 1
2 Cleistogamous flowers are invariably autogamous as the flower remains invariably closed so
pollination is strictly self pollination .
3 The Non coding sequences present within a gene called INTRONS. 1
4. The DNA sequences Restriction enzyme Eco RI recognize and cut is the Palindrome sequence
GAATTC
CTTAAG 1
5 .The conditions of the earth atmosphere conducive for the origin of life are Anaerobic
Environment, Water /Humidity, Electrical Discharge , NH3 .H , CO2, CH4 1
6. The dominant producers in a deep aquatic ecosystem are the phytoplanktons . The other
name that could be given to a primary consumer are herbivores. 1
7 The starting point of a detritus food chain are the non utilized and non assimilated components
of Grazing food chain. 1
8 Nutrophils act as cellular barriers to pathogens in Humans by transforming into
phagocytes. 1
Section B
9 Apomixis mimics sexual reproduction . In both apomixis and sexual reproduction production
of gametes takes place .Apomixis is different from polyembryony as in polyembryony fusion of gametes takes place . 2
10 Biotechnology has helped in improving life of Diabetic people by production of activated
Insulin that do not require processing. 2
11 Histone proteins helps in packaging of DNA to form the structure of chromatin fiber as they are octomers having +ve charge and DNA has –vely charge so it coils around it and is held together by H1 Linker histone subunit to produce nucleosome and many nucleosome condense to form chromatin. 2
13. Sickle shaped anemia is a six linked disorder as it shows sex linked cris-cross inheritance . The females can be carrier ,sufferer or normal but male are either sufferer or normal. 2
14 A person injured in road accident and requires immediate immune response was brought to doctor
i) The doctors immediately should inject preformed antibodies
ii) Passive immunity was provided to the patient.
iii) It is a kind of immunity that is developed by injecting preformed antibodies. 2
15 The beekeeper keep the beehives in the crop in the flowering seasons as more flowers for
nectar is present and also bees helps in pollination. 2
16 Eurythermal animals will survive the global increase in temperature because they can
withstand wide fluctuation of temperature . 2
17 The character is autosomal recessive
-If it were dominant then it would have appeared in all the members of the progeny
- If not sex linked then ,as it appeared in both male and female . 2
18 If the chromosome no in a plant species is 20 , the chromosome number and
the ploidy of the cells are as follows
i)Microspore mother cell - 20, (2 n)
ii)Endosperm cells - 30 (3 n ) 2
Section C
19 Fill in the gaps in the following table showing certain terms and meanings: 3
Terms
Meanings
I
Ii
Iii
Iv
V
vi
INTRONS
DNA FINGER PRINTING
Restriction enzymes
Plasmids
Tran genes
POINT MUTATION
Non coding sequence of DNA
Techniques used to solve paternity disputes
Enzymes that cut off DNA at specific sites
Automatically replicating circular extra chromosomal DNA.
Genetically modified organisms.
Nucleotide sequences with a single base differences
20 a) The part of female reproductive system in which the following events occur are :
i) Release of 1st Polar body : Tertiary follicle
ii) Release of 2nd Polar body : Ampulla
v)Fertilization : Ampulla
vi)Implantation : Endometrium of uterus.
b) The hormone that the female pituitary release for parturition is Oxytocin and the source of signal for the same is from fully developed foetus and placenta . 3
21 i) 1 – Terminator - It defines the end of Transcription
2- Promoter - It is the site that defines attachment site of RNA Polymerase.
3- Coding Strand - It does not code for any region of of RNA.
4- The sequence of coding strand will be similar to RNA transcribed.
ii) The Template strand of DNA ( 3’ 5’ ) will take part in making a meaningful copy of RNA . 3
22 The various simulation of primitive environment created in the experiment performed by Stanley Miller were as follows:
i) Primitive environment on earth – H , CH4 , NH3 gases in anaerobic condition .
ii) Energy source at the time of origin – Electrical discharge through electrodes and heating.
iii) Formation of organic molecule of life to prove the theory of chemical evolution –
Organic molecules like sugars ,nitrogen bases, fats and pigments have been formed. 3
23 Flogs are masses of anaerobic bacteria associated with fungal filaments to form mesh like structures.
- They consume major part of organic matter and reduce BOD.
- The effluents are passed to settling tank for sedimentation (called activated sludge)
- Activated sludge is pumped into aeration tank and serves inoculums.
- Remaining sludge is pumped back in digesters.
- Effluents from secondary treatment plant are released in natural water bodies. 3
24 a) The mechanism is called Insertational inactivation.
- Recombinant DNA is inserted in coding sequence of enzyme β- galactosidase and
inactivation of the enzyme takes place.
If the Plasmid of the bacteria do not have an insert, a blue colour is developed in presence of chromagenic substrate .
If blue colour Is not formed then it suggests correct insertion and formation of recombinant DNA .
b) It is advantageous as selectable markers are used, they differentiate between recombinant and non-recombinants based on their ability to produce colour. 3
25 ‘ A population has been exhibiting genetic equilibrium”
i) When the allelic frequency remains stable and is constant in generations it suggests genetic equilibrium.
ii) The underlying principle is HARDY WEINBERG Principle.
iii) Factors which will upset the genetic equilibrium of the population are
Gene flow, genetic drift, mutation, genetic recombination, and natural selection. ( any 2) 3
26. Figure 14.4 d NCERT Test book page no. 249
27. Figure5.5 NCERT Test book page no.75
SECTION D
28 Cry proteins are Crystal proteins produced in response to cry gene. The bacterium Bacillus
thuringiensis produce cry proteins .
-The cry protein is present as inactive protoxin but is activated as active toxin when ingested by
insects.
- The cry proteins are narrow spectrum insecticide.
- They binds to the midgut linings and causes pores and lysis killing the insect.
- The genes are incorporated in many plants like cotton (Cotton Bt) tomato, corm, rice etc and gets
resistant against the pest.
The cry gene used for control of cotton bollworms are Cry I Ac and Cry II Ab and for corn borer
Cry I Ab. 5
29 BOD is Biological Oxygen Demand and is increased due to more amount of anaerobic bacteria
which consume major part of organic matter and reduce BOD.
- BOD is a direct indicator of amount of organic pollutants present in water. Micro-organisms
involved in biodegradation of organic matter in the receiving water body consume a lot of
oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the
point of sewage discharge. This causes mortality of fish and other aquatic creatures.
The relationship of BOD and Dissolved oxygen is that as Dissolved oxygen level falls BOD increases.
BOD can be decreased in water body by reducing Organic waste pollution and by treatment of water.
30. In all communities the composition and structure constantly change in response to the changing environmental conditions over a period of time and is known as ecological succession .Succession occurring on previously occupied site is called Primary succession
Succession occurring on previously unoccupied site is called Secondary succession
Stages in Hydrarch succession :Phytoplankton’s free-floating angiosperms rooted hydrophytes sedges grasses trees(forest) With time the water body is converted into land .
Stages in Xerarch succession: lichens stage Bryophyte stage bigger plants climax forest community xerophytic habitat gets converted into a mesophytic.
In secondary succession since soil is already there, the rate of succession is much faster and hence, climax is also reached more quickly as compared to Primary succession where the soil or water is highly oligotrophic.
Sample Question Paper- II.
XII-BIOLOGY
Time: 3 Hours Max. Marks: 70
GENERAL INSTRUCTION:
(i)All questions are compulsory :
(ii)The question paper consists off our sections A, B, C and D. Section-A contains 8 questions of 1 mark each, Section B is of 10 question of 2 marks each, Section C has 9 questions of 3 marks each whereas Section D is of 3 questions of 5 marks each.
(iii)Wherever necessary, the diagrams drawn should be neat and properly labeled.
Section A
1.“In the Whiptail Lizards only females are born generation after generation. There are no males.” How is this possible?
2.When is the structure and composition of a community expected to remain unchanged?
3.AaBb was crossed with aabb. What would be the phenotypic ration of the progeny? Mention the term to denote this kind of cross.
4.In F. Griffith’s experiment, How did the non-virulent strain of streptococcus pneumoniae become virulent?
5.Expand the following.
a.PCR
b.Bt
6.Mention any two measures for prevention and control of alcohol & drug among adolescents.
7.In which directions are leading and lagging strands synthesized during DNA replication? Name the enzyme responsible for this process.
8.What does a J shaped growth curve of population indicate?
Section B
9.Given below in a sequence of steps of transcription in a eukaryotic cell. Fill up the blanks.
DNA --------------------------- RNA ------------------------- RNA--------
10.Given below is a graph depicting organism response to changing external conditions. According to their response the organisms are grouped into two types. Name the type which will show (i) pattern A and (ii) Pattern B.
11.List any four advantages of genetically modified crop plants over their wild / domesticated relatives.
12.Which one out of the eurythermal or stenothermal species is likely to survive increased global temperatures? Give one reason for your answer.
13.In case of Bt cotton, How does the toxic insecticide protein produced by the bacterium kill the insect pest but not the cell of Bacillus thuringiensis where the toxic protein is generated.
14.Sex determination is based on particular chromosomes in both birds and humans. State two points of difference between their mechanisms of sex determination.
15.State the principle underline “Gel electrophoresis” and mention two applications of this technique in biotechnology.
16.Name the type of inheritance in which the genotypic ratio is same as that of phenotypic ratio and give the ratio.
17.Draw and label an anatropous ovule.
SECTION-C
18.Draw a flow chart depict the multiplication of HIV virus into host cell.
19.What are “Flocs”? State their role in effluent treatment and their ultimate fate in sewage treatment tank.
20.What is DNA finger printing? Write its applications.
21.Draw a diagram of mature sperm and label any four parts.
22.What is Nucleosome? Explain its structure with simple diagram.
23.Write a note on Transcription.
24.Write the equation of Hardy-Weinberg principle / equilibrium. List the factors which effects Hardy-Weinberg principle / equilibrium.
25.Write short note on Hot-spots of biodiversity.
26.Give a diagrammatic representation of Phosphorus cycle.
27.
a.Write equation for Verhulst Pearl logistic growth where
N = Population density at a time t,
r = Intrinsic rate of natural increase
and K = carrying capacity.
b.Draw a graph for a population whose population density has rich the carrying capacity.
c.What is the logistic growth model considered a more realistic one for most animal populations?
d.Draw a growth curve where resources are not limited to growth of a population.
SECTION D
28.
a.Name the cell that develops into the embryo sac. And explain how this cell leads to the formation of embryo sac. also mention the role played by the various cells of the embryo sac.
a.Show diagrammatically the stages of embryonic development from zygote up to implantation in humans.
29.Name the genes that constitute an operon. How does lac operon get switched on in the presence of Lactose?
30. Diagramatically show linkage in Drosophila.
SOLUTIONS
SECTION-A
Ans1: It is due to Parthenogenesis.
Ans2: Climax community during ecological succession.
Ans3: Phenotypic ratio 1:1:1:1, Test cross.
Ans4: Transformation.
Ans5:
a.Polymerases Change Reaction,
b.Bacillus thuringiensis.
Ans6: i) Avoid undue pressure on the child, ii) Education and counseling will be worth while
through channelise the child energy into healthy pursuits like sports, reading, music, yoga and other activities.
Ans7: 5’ 3’, 5’ 3’; DNA Ligase.
Ans8: Starvation and mass mortality.
SECTION- B
Ans9:
a)RNA Polymerase II
b)hnRNA (Heterogenous nuclear RNA)
c)Messenger RNA
d)Adenylate residues
Ans10:
A)Conformers
B)Regulators
Ans11: Advantages of genetically modified crop plants:
i)They have proved to be extremely valuable tools in studies on plant molecular biology, regulation of gene action, identification of regulatory / promotory sequences.
ii)Genetically modified crops have improved agronomic and other features such as resistance to biotic and abiotic stresses.
iii)Transgenic plants have been produced that express a gene encoding an antigenic protein from a pathogen
iv)It provides better nitrogen fixation.
Ans12: Eurythermal plants have better survival ability
These plants can tolerate and thrive in wide range of temperature.
Ans13: The toxic insecticide produced by the bacterium in case of Bt cotton plant is coded by a gene cry. The Bt toxin protein exist as inactive protoxin but once an insect ingests the inactive toxin, it is converted into active form due to alkaline pH of gut with solublise the crystal thus active toxin kills the insect.
Ans14: In human the males have XY chromosomes and females XX where as in birds males are Homomorphic (ZZ) and females are Heteromorphic (ZW).
Ans15: As DNA fragments are negatively charged molecules they can be separated by forcing them to move towards an anode under an electrode field through a medium
Application:
v)In genetic engineering for constructing recombinant DNA
vi)DNA finger printing.
Ans16: Incomplete dominance, 1: 2: 1
Ans17: Figure (d): NCERT page No.25
Section C
Ans18: Figure(8.6): NCERT Page No. 155
Ans19: There are masses of bacteria associated with fungal filament to form mesh like structure.
These flocs consume major part of organic matter in the effluents and reduce the BOD (Biological Oxygen Demand) of effluents.
As the BOD of sewage or water is reduced the effluent is than passed into settling tank where the bacterial flocs are allowed to sediment. This sediment is called activated sludge
Ans20: DNA Finger Printing
DNA Finger printing is a technique to identify a person on the basis of his / her DNA specificity by the means of their digital / palmer print. Each person has a unique DNA finger print.
Application of DNA fingerprinting:
I. In forensic laboratories for identification of criminals.
II. Paternity disputes to find real parents can be solved by DNA fingerprinting.
III. It is useful in determining population and genetic diversities.
IV. It is used to study the breeding patterns of animals facing the danger of extinction.
Ans21: figure (3.6): NCERT Page No. 48
Ans22:
The distance between two consecutive base pairs is 0.34 nm (0.34 x 1O-9m). If the length of DNA double helix in a typical mammalian cell is calculated (simply by multiplying the total number of bp with distance between two consecutive bp, that is, 6.6 x 109 bp x 0.34 x 10-9 m/bp), it comes out to be approximately 2.2 meters. A length that is far greater than dimension of a typical nucleus (approx. 10-6m).
In eukaryotes, this organization is much more complex. There is a set of positively charged, basic proteins called 'histones'. A protein acquires charge depending upon the abundance of amino acids residues with charged side chains. Histones are rich in amino acids residue Iysines and arginines. Both the amino acids residues carry positive charges in their side chains. Histone organized to form a unit of eight histone molecules called as 'histone octamer'. The negatively charged DNA is wrapped around positively charged histone-octamer to form a structure called 'Nucleosome'. A typical nucleosome contains 200 bp of DNA helix. Nucleosomes constitute the repeating unit of a structure in nucleus called 'Chromatin', thread-like stained (coloured) bodies seen in nucleus. The nucleosomes in chromatin are seen as "beads-an-string" structure where viewed under electron microscope (EM).
Ans23:
* The process of copying genetic information from one strand of the DNA into RNA is called transcription.
* Principles of complementarities govern the process of transcription; the exception is that uracil is incorporated instead of thymine opposite adenine of template.
* Only a segment of DNA is transcribed and that only one of two strands is copied.
* Both the DNA strands cannot be copied in transcription because that will produce two types of proteins, one with correct sequence of amino acids and the other with reverse sequence of amino acids.
* Further if two complementary RNA’s are produced simultaneously, they would have a tendency to form double stranded RNA resulting in non translation of coded information into proteins. The whole exercise of transcription would then appear futile.
Ans24:
Hardy-Weinberg Equation:
p2 + q2 +2pq = 1
Factors which affect Hardy-Weinberg equilibrium:
vii)Gene migaration / gene flow
viii)Genetic drift
ix)Mutations
x)Genetic recombination
xi)Natural selection
Ans25: The concept of “Hot-spot” was developed by Norman Myers (1988) to designate specific areas for in-situ conservation. The Hot-spot are the richest and the most threatened reservoirs of plants and animal live on earth.
The criteria for determining Hot-Spots are:
xii)no. of endemic species.
xiii)Degree of threat which is measured in terms of habitat loss.
There are 25 Hot-Spots in the world out of which two are in India. They are Western Ghats & Eastern Himalayas.
Hot spot of Eastern Himalayas are active centers of evolution and rich in diversity of flowering angiosperms.
Western Ghats have semi evergreen forests. Western Ghats includes two main centers of bio diversity, i.e., Aqustyamalai Hills and Silent Valley.
Ans26: Figure (14.7) NCERT Page No. 255.
Ans27:
a) ------- = rN (------------)
b) Population whose population density has reacted the carrying capacity.
c) Since resources for growth for most animal populations become limited sooner or later, the logistic growth model is concerned a more realistic one.
SECTION D
Ans28:
a)The functional megaspore form female gametophyte. The nucleus of megaspore divides into two, four and finally eight daughter nuclei. Four of which are located at each pole. One nucleus from each pole migrates to the centre of form two polar nuclei which further fuse to form a diploid fusion or secondary nucleus. Three nuclei at the base of embryo sac form antipodal cells. The remaining three nuclei at the micropylar end get surrounded by cytoplasm to form pyriform cells. These three cells together constitute egg apparatus, which consists of two cells known as synergids and an egg which hangs between them the egg cell on fertilization gives rise to zygote, while synergids get disorganized soon after fertilization. Then antipodal cells sooner or later also get disorganized. They may however, be nutritive in function.
b)Stages of development of from zygote up to implantation.
Ans29: Lac operon genes that constitute operon
i) Promoter Genes, ii) Operator Gene, iii) Structural Gene, iv) Regulator Gene.
Switching on of Lac Operon.
* In Lac-Operon the regulator gene is called i-gene because it produces an inhibitor or repressor. The repressor binds to operator gene and turn off the Operon. It exerts a negative control over the working of structural genes.
* Structural genes are those genes which actually synthesize mRNAs. The Lac-Operon of E-Coli contains three structural genes (z, y, a).
* The ‘z’ gene codes for -galctosides which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units galactose and glucose. The ‘y’ gene codes for permease, which increases permeability of the cell to -galctosides. The ‘a’ gene encodes a transacetylase.
* Operator gene is a gene which directory controls the synthesis of mRNAs over the structural gene. It is switched off by the presence of a repressor. An inducer can take away the repressor and switch on the gene. When switch on the structural gene synthesis of polypeptide chain, i.e., transcription and translation occur.
* Promoter gene acts as an initiation signal which functions as recognition centre for RNA polymerase provided the operator gene switch on. RNA polymerase is bound to the promoter gene. When the operator gene is functional, the polymerase moves over it and it reaches the structural genes to perform transcription.
* The repressor of the operon is synthesized from the i-gene. The repressor protein binds to the operator region of the operon and presents RNA polymerase from transcribing the operon. In the presence of an inducer such as lactose or allolactose, the repressor is inactivated by interaction with the inducer. This allows RNA polymerase access to the promoter and transcription proceeds.
* Inducer regulator switching on of the operon. The inducer of Lac-operon of Escherichia coli is lactose (actually allolactose).
30.Figure 5.11 NCERT Test book page no.84.
SAMPLE PAPER-III
SUB: BIOLOGY
CLASS: XII
Time: 3 Hrs Max. Marks:70
General Instructions:
i).This question paper consists of four sections A,B,C, D. Section A contains 08 questions each carrying 1 mark. Section B of 10 questions of 2 marks each. Section C is of 09 questions of 3 marks each, and Section D is of 5 marks each.
ii) All questions are compulsory and give labeled diagram wherever necessary
iii) Question numbers 1 to 8 are to be answered in one word or one sentence each.
iv) Question numbers 9 to 18 are to be answered in approx 20 to 30 words.
v) Question numbers 19 to 27 are to be answered in approx 30 to 50 words.
vi) Question numbers 28 to 30 are to be answered in approx 80 to 120 words.
SECTION-A
1. Name asexually reproducing unit of sponge.
2. What is plasmid ?
3. What are ‘transgenic bacteria’?
4. Define standing crop.
5. Write ‘logistic growth equation’.
6. The nitrogenous base sequence in template DNA strand is ATTCGATGCTAC .What would be the nitrogenous base sequence in the mRNA transcribed by DNA strand.
7. Define cellular totipotency.
8. Name the causative organism of the disease Ringworms.?
SECTION :B
9. Give any four advantages of vegetative propagation in plants?
10. Describe any two accessory reproductive glands in human male?
11. Explain the mechanism of incomplete dominance with the help of cross?
12. Differentiate between homologous and analogous organs with the help of one suitable examples from plants and animals?
13. Briefly explain the four barriers of innate immunity?
14. Name the soil bacterium which produces protein that kills the certain insects that kills insects? Mention its uses ?
15. List any two important applications of gene therapy?
16. What is restriction enzymes? Distinguish between sticky and blunt end?
17. Define ecological pyramids. Under what conditions pyramid of no looks inverted?
18. Why there is need for conservation of biodiversity? Briefly distinguish in-situ and ex-situ conservation?
SECTION :C
19. Describe Messlson and Stahl experimental proof of semi conservative mode of DNA replication with diagram?
20. Define operon . Describe lac operon with the help of diagram.
21. Differentiate between:
(a) B and T cells
(b) Write the name of primary lymphoid organs where lymphocyte differentiate.
(c) Name the two types of immune response.
22. Describe Urey and Miller Experiment with the help of labeled diagram.
23. Explain the methods of plant breeding for developing resistance to insect pest. What is fortification?
24. What is bio fertilizer. Give there advantages over chemical fertilizers. What is endo and ectomycorrhizae?
25. Explain the process of succession in aquatic ecosystem?
26. Define the decomposition and describe the process and product of decomposition.
27. (a) What is the significance of slope of regression in an species area relationship.
(b) Distinguish between primary and secondary productivity.
SECTION-D
28. Explain the female sexual cycle. Also mention why the half of cycle is called as follicular and second half the luteal phase?
OR
Give the schematic representation of spermatogenesis with the help of diagram. Where does this take place?
29. Define central dogma of molecular biology. Explain the process of translation.
OR
How did Hershey and Chase prove that DNA is the genetic material?
30. Explain various steps in the formation of recombinant DNA by the action of restriction enzyme in E.coli with the help of diagram.
OR
(a) Compare and contrast the advantages and disadvantages of GM crops.
(b) Name the organization set up by Indian Government responsible for taking decision regarding GM research.
(c) What is Biopiracy?
-X-
SOLUTION
1:- Gemmule
2:- Autonomously replicating circular extra chromosomal DNA in bacterial cell.
3:- Bacteria whose genes have been altered by manipulation.
4:- Each traffic level has a certain mass of leaving material at a particular time.
5:- Dn/dt = rN[(K-N)/K]
6:- UAGCAAUAUCGG
7:- The capacity of a single cell to form the whole organism .
8:- Trichophyton/ Epidermophyton/Microsporum
9:- a) Indefinite growth without variation
b) Disease free plant
c) Study about physico-chemical treatment
d) To overcome prolong period of seed dormancy.
10:- Seminal vesicle/Prostrate gland/Cowpers gland.
11:-
Ans. Sometimes, the offsprings of F1 generation does not express the character of dominant parent, but produce an another character. This process is known as incomplete dominance.
e.g. Antirrhinum(a pink flower) mixed variety of red and white flower.
RR(red) rr(white)
R R r r
Rr Rr Rr F2 ratio: 1:2:1
(RED:PINK:WHITE)
12:- . The organs which perform different functions but have the similar basic structure, and similar embryonic origin are called as homologous organs but analogous organs are the organs having the same function but are quite different in embryonic origin.Homology is based on divergent evolution but analogy is based on convergent evolution.Example of homologous organs: vertebrate forelimbs, thorns and tendrils of cucurbita plant.
example of analogous organs :insect and bird wings, leaves of cladodes.
13:- The four barriers of innate immunity are :
1. Physical Barriers: skin on our body is the main barrier which prevents entry of micro-organisms.
2. Physiological Barriers: Acid in the stomach, saliva in the mouth, tears from eyes prevent microbial growth.
3. Barriers: Polymorpho-nuclear leucocytes and natural killer in blood, macrophages in tissues can phagocyte and destroy microbes.
4. Cytokine Barriers: Virus infected cells secrete proteins called Interferons which protect non infected cells from further viral infection.
14:- Bacillus thuringiensis . As insecticides/pesticides .
15:- Two important applications of Gene Therapy are listed below:
1.Insertion of genes into an individual cells and tissues to treat diseases especially hereditary diseases.
2.Viruses that attack their hosts and introduce their genetic material into the host cell as part of their replication cycle are used as vectors to transfer healthy genes or more recently portions of genes.
16:- The enzyme which cuts the DNA.
Sticky End:- The end which helps to join the foreign DNA.
Blunt End :- The terminal part of DNA which can not join the foreign DNA.
17:-The Pyramid appears due to the no of producer, consumer, and decomposer of a
biological system is known as ecological pyramid .
Example :- Insects on a big tree or biomass of fish feeding on plankton.
18:- The need for conservation of bio-diversity is to realize that every species has an
intrinsic value, even if may not be of current or any economical values to us.
In-Situ conservation: The endangered species are protected in their natural habitat so that the entire ecosystem is protected.
Ex-Situ conservation: It includes the protective maintenance of threatened species in zoological parks and botanical gardens.
19:- MATHEW MESSELSON and FRANKLIN STAHL performed the following experiment to prove the semi-conservative mode of DNA replication.
1. They grew E.Coli in a medium containing 15NH4CL as the only nitrogenous source for many generations. The result was that 15N was incorporated into newly synthesized DNA.
2. Then they transferred the cell into a medium with normal 14NH4CL and extracted the DNA that remain as a double stranded helix
3. Thus the that was extracted from the culture one generation after the transfer from 15N to 14N medium had a hybrid or intermediate density. This DNA contained of equal amounts of this hybrid DNA and of light DNA.
20:- Operon is a segment of DNA that comprises one or more adjacent structural genes, an operator gene and a regulator gene.
The Lac operon consists of one regulatory gene and three structural genes.
The i-gene codes for the repressor of the lac open. The z-gene codes for the Beta-galactosidase which is primarily responsible for the hydrolysis of disaccharide lactose into its monomeric units (galactose and glucose).The y gene codes for permease which
increases permealibility of the cell to B-galactosides. The a-gene encodes a transacetylase.
21:- a) The B lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them. These proteins are called Antibodies.
But the T-cells themselves do not secrete antibodies but help B-cells to produce them.
b) The primary lymphoid organs where the lymphoid organs where the lymphocyte differentiate are bone marrow and thymus.
c) The two types of immune response are active immunity and passive immunity.
22:- UREY and MILLER designed a glass flask, a condenser, and a liquid flask interconnected with tubes and fitted with sources of energy. The apparatus a mixtures of methane, ammonia and hydrogen in the ratio of 2:2:1 and water vapour. They provided energy for the interaction of the gases present in the mixtures in the form of electric sparks of 75,000 volts from electrodes in liquid flask. A mixtures of small organic molecules was formed in the gas flasks and was carried by condensation to the liquid flask. They found simple organic compound which included amino acids such as glycine, alanine and aspartic acid, adenine and simple sugars such as ribose.
23:- The main steps in breeding a new genetic variety of a crop are:
Collection of variability
Evaluation and selection of parents
Cross hybridization among the selected parents
Selection and testing of superior recombinants
Testing, release and commercialization of new cultivators.
Fortification – breeding crops with higher levels of vitamins and minerals or higher protein and healthier protein fats – is the most practical means to improve public health.
24:- Bio – fertilizers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilisers are bacteria, fungi and cyanobacteria.
Advantages of biofertilisers:
Bio – fertilizers do not cause atmospheric pollution
Bio – fertilizers are cheep and economical
They excrete antibodies and thus act as bio pesticides.
Ectomicorrhizae is the form of association where the fungal mycelium completely encloses the feeder rootlets forming sheath or mantle.
Endomicorrhizae is the form of association in which the fungus does not form an external sheath or mantle.
25:- In primary succession in water, the pioneers are the small phytoplanktons, they are replaced with tie by free-floating angiosperms, then by rooted hydrophytes, sedges, grasses and finally the trees. The climax again would be a forest. With time the water body is converted into land.
In secondary succession, the species that invade depend on the condition of the soil, availability of water, the environment as also the seeds or other propagules present.
26:- Decomposition is the process of breakdown of complex organic matter into
inorganic substances like carbon dioxide, water and nutrients. The important steps in
the process of decomposition are Fragmentation, Leaching, Catabolism, humification
and mineralization.
Detritivores(e.g., earthworm) break down detritus into smaller particles. This process is called Fragmentation. By the process of Leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. Bacterial and Fungal enzymes degrade detritus into simpler inorganic substances. This process is called s Catabolism.
Humification leads to accumulation of a dark coloured amorphous substances called Humus that is highly resistant to microbial action and undergoes decomposition.
The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as Mineralization.
27:- Primary productivity is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis.
Secondary productivity is defined as the rate of formation of new organic matter by consumer.
28:- The gamete formation in females is a cyclic activity that takes place after about every
28 days and involves changes in the structure and the function of the entire
reproductive system of females is called Menstrual Cycle or Sexual cycle of Female.
Follicular Phase: This phase lasts for bout 14 days. It comprises of the following events:
The Pituitary lobe secrets the follicle stimulating hormone(FSH)
The FSH stimulates the growth of the primary oocyte inside this follicle.
The FSH also stimulates the follicle cells to secrete Estradiol.
The L.H. induces the mature Graafian Follicle to burst and eject its eggs into the fallopian tubes. This is called as Ovulation .
Luteal Phase: This phase lasts for about 10 days. It comprises the following events:
a). The peak of LH together with Prolactin hormone from the pituitary lobe stimulates the follicular cells of empty Graafian follicle to form a yellow body called Corpus Luteum.
b). The Progesterone and Estradiol continue the hypertrophy of the endometrial lining in the uterus and the fallopian tubes.
c). The Progesterone inhibits the release of FSH so that it may not develop additional follicles and eggs.
OR
1)Formation of Spermatids: This process has three phases :
Multiplication phase: The undifferentiated germ cells present in the seminiferous tubules of testes are called Spermatogonia multiply by mitotic cell division.
Growth phase : On sexual maturity , some spermatogonia stop dividing and grow in size by accumulating cytoplasm and replicating DNA and are termed as primary Spermatocytes.
Maturation phase : The primary spermatocytes undergo first meiotic(reductional) division and produce secondary spermatocytes. The secondary spermatocytes undergo the second meiotic(equational) division and produce spermatids.
2) Formation of Spermatozoa:
The spermatids do not divide further and modify into spermatozoa (haploid).A spermatogonium produces four spermatozoa. The transformation of spermatids into spermatozoa is known as Spermiogenesis.The process of release of spermatozoa from sertoli cells into the seminiferous tubules is called as spermiation.
29:- CENTRAL DOGMA: the proposition of double helix structure for DNA and its simplicity in explaining the genetics became revolutionary. Very soon Francis Crick proposed the Central Dogma in molecular biology which states that the genetic information flows from DNA-RNA-PROTEIN.
Translation: Translation refers to the process of polymerization of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence of nitrogenous bases in the m-RNA.The amino acids are jointed by a bond which is known as a peptide bond. Formation of a peptide bond requires energy.Therefore,in the first phase itself amino acids are activated in the presence of ATP and linked to their t-RNA-a process commonly known a Charging of t-RNA.
OR
The unequivocal proof that DNA is the genetic material came from the experiments of Alfred Hershey and Martha Chase. They worked with viruses that infect bacteria called Bacteriophages.
The bacteriophages attaches to the genetic material of bacterial cell. Hershey and Chase worked to discover whether it was protein or DNA from the viruses that entered the bacteria.
They grew some viruses on two different mediums that contained radioactive phosphorus and radioactive sulfur. Viruses grown in the presence of radioactive phosphorus contained radioactive DNA only. Similarly viruses grown on radioactive sulfur contained radioactive protein only.
Radioactive phages were allowed to attach to E.Coli bacteria. Then as the infection proceeded the viral coats were removed from the bacteria by agitating them in a blender. The virus particles were separated from the bacteria by spinning them in a centrifuge.
Bacteria which was infected with viruses having radioactive DNA were radioactive indicating that DNA was the material that passed from the viruses to the bacteria.
Bacteria which was infected with viruses having radioactive indicating that DNA was the material that passed from the virus to the bacteria. Bacteria that were infected with viruses having radioactive proteins were not radioactive. This indicates that proteins did not enter the bacteria from the viruses. DNA is therefore the genetic material that is passed from virus to bacteria.
30:- Restriction enzymes cut the strand of DNA a little away from the centre of the
palindromic sites but between the same two bases on the opposite strands. This
leaves single stranded proteins at the ends. There are overhanging stretches
called Sticky Ends on each strand. This stickiness of the ends facilitates the action
of the enzyme DNA Ligase.
Separation and isolation of DNA fragments :
The cutting of DNA by restriction endonucleases results in the fragments of DNA.
These fragments can be separated by a technique known as GEL ELECTROPOROSIS. Since DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium.
The separated DNA fragments can be visualized only after staining the DNA with a compound known as Etidium Bromide followed by exposure to UV Radiation.
The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. The step is known as Elution. The DNA fragments purified in this way re used in constructing recombinant DNA by joining them with cloning vectors.
OR
(a) Normal physiology and development
Study of disease
Biological product
Vaccine safety
Chemical safety testing etc.
(b) GEAC
(c) Biopiracy:- Is the term used to refer to the use of bio-resources by multinational
companies and other organizations without proper authorization from the country and people without compensatory payment.
-: END :-
BIOLOGY (Theory)
PAPER - IV
Time allowed: 3 hours. Maximum Marks: 70
General Instructions:
i. All questions are compulsory.
ii. This question paper consists of four sections A,B,C and D section A contain 8 questions of one mark each, section B is of 10 question of two marks each, section C is of 9 questions pf three marks each and section D is of 3 questions of five marks each.
iii. There is no over all choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and all the three questions of 5 marks weightage.
iv. Wherever necessary, draw neat and properly labeled diagrams.
SECTION- A.
1. What is Gause’s ‘Competition Exclusion Principle’?
2. What is Dobson unit (DU)?
3. What is contact inhibition?
4. Name the homologous organs of tendrils in cucurbits.
5. Name the organisation set up by govt. of India to make decisions about genetically modified organisms.
6. Mention a & b-
7. What are bioreactors?
8. What is inbreeding depression?
SECTION- B.
9. What is multiple allelism? Give example.
or
Which Mendel’s law is universally accepted? Define the law.
10. What is relationship between Cuckoo (Koel) and crow and which one is benefited?
11. What are pyramids of number and pyramid of mass?
12. Which technique is used to separate DNA segments? What is bases of this
technique?
13. What is Apomixis and polyembryony? Give examples also.
14. Expand- i. MTP, ii. VD, iii. RTI, iv. PID.
15. What is Hardy Weinberg Principle? Give Mathematical equation also.
16. Why do adolescents fall a victim of Drugs?
17. What is biomagnification? Give Example.
18. Name the microbes used in
a. Formation of Swiss cheese.
b. Roquefort cheese.
SECTION- C.
19. Explain Griffith transformation Principle.
20. Give the causative agent of common cold, its symptoms and mode of
transmission.
21. Explain the following properties of genetic code
i. Unambiguous, ii. Degenerate, iii. Universal.
22. What are the three type of natural selection? Explain.
23. Explain DNA amplification by using PCR.
or
How first Recombinant DNA was formed?
24. What is green house effect? What are green house gases? What is its importance?
25. Show the different stages of structure formed from ovution to Blastocyst in human beings.
26. Explain the carbon cycle.
27. Show with the help of well labeled diagram biogas plant.
SECTION- D.
28. How genetically modified plants are useful?
or
What gene therapy? Explain the 1st case of gene therapy.
29. Explain Watson and crick model of DNA
or
Show with the help a dihybrid cross linkage between y & w genes in Drosophila.
30. What is spermatogenesis? Explain.
or
a. What is double fertilization?
b. Draw a well labeled diagram of L.S. of anatropous ovule.
SOLUTIONS
Section A
Ans 1 : It states that two closely related species competing for the same resources cannot co-exist independently
Ans 2 : It the unit of thickness of ozone layer.
Ans 3: It is the property of normal cells by virtue of which contact with other cells inhibits there uncontrolled division.
Ans 4: Thorns of Bougainvillea
Ans 5: GEAC
Ans 6. a promoter , b Structural gene
Ans 7 : A bioreactor is a large vessel in which raw materials are converted into specific products biologically.
Ans 8: Continuous in breeding reduces fertility. This is called inbreeding depression.
Section B
Ans 9: When a character is controlled by more than two alleles. Eg : ABO Blood Groups. Or Law of Segregation. During gamete formation allelic pair gets separated and paired conditions are restored by fusion of gametes.
Ans 10 : Brood parasitism. Cuckoo
Ans 11: Pyramid of number :- It is the graphical representation of the number of individuals at each trophic level. Pyramid of mass :- It is the graphical representation of the amount of mass at each trophic level.
Ans 12 : Gel Electrophoresis Size of the DNA segments.
Ans 13: Apomixis:- Formation of seed without fertilization. Eg : Grasses
Polyembryony : - Occurrence of more than one embryo in a seed. Eg: Citrus
Ans 14 : (i) Medical Termination of Pregnancy (ii) Vernal Disease
(iii) Reproductive Tract Infection (iv) Pelvic Inflammatory Disease
Ans 15 : It states that gene frequency remain constant in a population
(p + q) 2 = 1, where p is frequency of Dominant allele and q is the frequency of recessive allele.
Ans 16 : Curiosity, need for adventure, experimentation and peer pressure
Ans 17 : Biomagnification :- The phenomena of increasing concentration of the harmful chemicals at each trophic level in a food chain is called Biomagnification. Eg : The increase in concentration of DDT is given below.
Water Zooplanktons Small Fish large fish Fish eating birds
(0.003ppm) (0.04 ppm) (0.5ppm) (2 ppm) (5 ppm)
Ans 18: (a) Bacteria – Propionibacterium Sharamanii
(b) Fungus
Section C
Ans 19 : In 1928 he did a series of experiments with Streptococcus pneumoniae bacterium responsible for pneumonia. Two strains of this bacteria rough (R) and smooth (S) are present.
S strain inject into mice mice dies
R strain inject into mice mice live
S strain inject into mice mice live
(Heat killed)
S strain + R strain inject into mice mice dies
He concluded that genetic material of heat killed S transform R type into S type.
Ans 20 : Caused by a group of viruses Rhinoviruses
Symptoms are nasal congestion and discharge sore throat, hoarseness’, cough, headache, tiredness etc.
Transmitted through contaminated objects such as pens, books, cups, doorknobs, computer keyboard or mouse etc.
Ans 21 : (i) Unambiguous : One codon codes for only one amino acid
(ii) Degenerate : Some amino acids are coded by more than one codon.
(iii) Universal : The codes are nearly same from bacteria to human beings.
Ans 22 : (i) Stabilizing : medium sized individuals are favored.
(ii) Directional : either small or large sized individuals favored.
(iii) Disruptive : both large and small sized individuals are favored
Ans 23 : There are three steps in DNA amplification by PCR:
(i)Denaturation (ii) Annealing with primer (iii) Extension of primer
Practice Diagram 11.6 NCERT Text Book Page no.: 202
Or
It was made by Stanley Cohen and H. Boyer in 1972. They cut the antibiotic resistance gene from the plasmid of Salmonella typhimurium by restriction enzymes. The cut piece of this plasmid then linked with related plasmid by enzyme ligase. This makes first recombinant DNA in vitro.
Ans 24: The Greenhouse effect is naturally occurring phenomena due to gases that is responsible for heating of the earth surface by re-radiating heat radiations in earth’s atmosphere. Green house gases are CO2, CH4, CFCs and N2O. – The average temperature will reduce to – 18o Celsius.
Ans 25: Figure 3.11 NCERT Text Book page No-52
Ans 26 : Carbon Cycle: Cyclic flow of carbon between biotic and abiotic components of environment is called Carbon cycle.
Fig:14.6 NCERT Text Book page No- 253
Ans 27 : Fig : 10.8 NCERT Text Book page No-186
Section D
Ans 28 : Genetical modification has :-
1.made crops more tolerant to abiotic stress.
2.Reduced reliance on chemical pesticides
3.Helped to reduce post harvest losses.
4.Increase the efficiency of numeral use
5.Enhanced nutritional value of food eg: Vitamin A enriched rice
Or
Gene therapy is a collection of methods that allows correction of a gene defect that has been diagnosed in child/ embryo.The first clinical gene therapy was given in 1990 to a four year old girl with adenosine deaminase (ADA) deficiency.
First step in gene therapy was lymphocytes from then blood of the patients are given functional ADA cDNA then these lymphocytes were returned to the patient.
If the genes are isolated from bone marrow cells producing ADA is introduced into cell at early embryonic stages it could be a permanent cure.
Ans 29 : In 1953 J. Watson and Crick based on X-ray diffraction data proposed double helix model of DNA. Salient features of this model :-
(a)It is made up of two polynucleotide genes where the backbone is constituted by sugar and phosphate and nitrogenous bases project inside.
(b)Two chains are anti parallel
(c)Bases are paired by Hydrogen bonds. Pairing is complementary Adenine pairs with thymine by double bond guanine pairs with cytosine by triple bond.
(d)The two chains are coiled in right handed patient. The pith of helix is 3.4 nm.
(e)The plane of one base pair stacks over the other in double helix
Fig:6.3 NCERT Text Book Page no:98
OR
Fig :5.11 Cross A only NCERT Text Book Page no: 84
Ans 30 : Spermatogenesis: The process of formation of sperms from male germ cell in the testis is called Spermatogenesis. It is divided into three phases : -
(i)multiplicative phase- spermatogonia divided my mitosis
(ii)Growth phase- some spermatogonia grow in size and form primary spermatocyte
(iii)Maturation phase- Primary spermatocyte undergo first mitotic division form haploid secondary spermatocyte which will undergo meiosis II to form haploid spermatids
The spermatids are transformed into sperms by the process called spermiogenesis.
Fig : 3.8(a) NCERT Text Book page no:49.
Or
(a)Double fertilization : One of the male gamete fuses with egg nucleus this is called syngamy. The other male gamete fuses with two polar nucleus which is called triple fusion. Since, two fusions syngamy and triple fusion are taking place in an embryo cell, this phenomena is called double fertilization.
(b) Fig : 2.7(d) NCERT Text Book Page No : 25.
PRACTICE SAMPLE PAPER - V
SUBJECT- BIOLOGY
INSTRUCTION:-
(i)Questions from 01 to 08 carry 1 marks each.
(ii)Questions from 09 to 18 carry 2 marks each.
(iii)Questions from 19 to 27 carry 3 marks each.
(iv)Questions from 28 to 30 carry 5 marks each
Section A
Q1. Give technical term of the following: transfer of pollen grains.
Q2. By which technique you can get unlimited number of pathogen free plants.
Q3.What is GMO?
Q4. Write two points in favour of “the DNA is a better genetic material than RNA”?
Q5. Name the ‘terror of Bengal’. Why it is called so?
Q6. What is the role of baculoviruses in pest management programmed?
Q7. Why are pollen grains produced in enormous quantity in maize?
Q8. Give an equation to find out the population growth.
Section –B
Q9. Differentiate between Dormancy and Quiescence.
Q10. Given below is the template strand of the DNA duplex- 3’- TAC CGA TCC GAG
CTG-5’
a) Give the complementary DNA polynucleotide chain.
b) Construct the RNA molecule, which will be transcribed.
Q11. Draw a diagram of dicotyledonous embryo and label its four parts.
Q12. a) Give the scientific name of the bacterium which produces cry proteins.
b)How are these proteins useful in agriculture?
Q13. Give any four salient features of genetic code.
OR
Give salient features of chromosomal theory of inheritance.
Q14. What are homologous organs? Give examples of both plants and animals showing
homology.
Q15. a) A bird eats herbivorous insects. Find the trophic level of the bird.
b)Find the energy in joules available at thirds trophic level, if at first trophic level 1000 Joules energy was available.
Q16. Define somatic hybridization. What are the different steps?
Q17. Define particulate matter? How do particulate matters harm human health.
Q18. Mention the difference between autosomal disorder and sex chromosomal disorders.
Section –C
Q19. Draw the labeled diagram of
a)Continuous replication of DNA.
b)Discontinuous replication of DNA
Q20. What are the different methods of birth control?
Q21. Give three major groups of drugs with examples and their effects on human beings.
Q22. Write a short note on diary farm management.
Q23. What is meant by ‘transcription unit’? What are its components?
Q24. Draw a neat and labeled diagram of human sperm.
OR
Draw a neat and labeled diagram of L.S. of angiosperms ovule.
Q25. Explain important goals of Human genome project.
Q26. a) Write two features of ‘biodiversity hotspots’.
b) Write three hot spots regions of India.
c)What was pledge by countries in the World Summit held in 2002 in Johannesburg?
Q27. What are the different stages in life cycle of plasmodium (Malarial parasite).
Section-D
Q28. a) Where does Oogenesis take place?
b)Explain diagrammatically the stages of the process of oogenesis.
OR
a)What is menstruation?
b)Explain the specific role of FSH, LH, estrogen and progesterone in the menstrual cycle.
Q29. a) Explain the role of mRNA, tRNA and rRNA during bacterial transcription.
b) Show three steps of bacterial transcription with the help of a diagram.
Q30. a) Discuss the causes and effects of global warming.
b)What measures need to be taken to control global warming?
OR
a)Define ecological pyramid and describe with examples pyramids of number and biomass.
b)What is meant by an inverted pyramid?
BEST OF LUCK TO ALL OF YOU FOR YOUR FORTHCOMING BOARD EXAMINATONS.
