Biology chapter wise important questions

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CHAPTER 1
REPRODUCTION IN ORGANISMS TEACHING HOURS -05
WEIGHTAGE OF MARKS – 05
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ONE MARK QUESTIONS
1. What is life span?
Life span is the period from birth to natural death of an organism.
2. Write the life span of the following organism/s.
ORGANISM LIFE SPAN
Elephant 65 – 90 years
Lion 25 years
Horse 30-40 years
Dog 20-30 years
Cow 20 – 25 years
Crocodile 60 years
Tortoise 100 – 150 years
Crow 15 years
Parrot 140 - 150 years
Butter fly 1 - 2 weeks
Fruit fly 20 – 30 days
Ostrich 50 years
Banyan tree More than 700 years
Banana plant 2 – 3 years
Rice plant 3 – 7 months
3. Define clone.
The individuals that are morphologically and genetically similar to the parent are called clone.
4. Mention the different means/ methods of asexual reproduction with example.
· Cell division - Protista, Monera
· Binary fission – Amoeba, Paramecium
· Budding – Yeast
· Zoospores (microscopic motile endogenous spores) – aquatic fungi, chlamydomonas
· Conidia (microscopic immotile exogenous spores)- pencillium
· External buds – hydra
· Internal buds like gemmules – sponges (spongilla)
5. Unicellular organisms are immortal. Justify.
Single celled organisms like amoeba & bacteria reproduce by cell division and there is no natural death for them.
Hence they are considered as immortal.
6. How vegetative reproduction does take place in Bryophyllum?
The adventitious buds or epiphyllous buds arise from the notches present at the margin of leaves grow into
independent plants.
7. Name the mode of reproduction that ensures creation of new variants.
Sexual reproduction.

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8. How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?
The progeny formed from asexual reproduction are genetically similar to the parents, but offsprings formed by
sexual reproduction show genetic variations due to genetic recombination occurred during gamete formation
and random fertilization.
9. Name the species of plant that flowers once in life time.
Bamboo species flowers only once in life time generally after 50 – 100 years.
10. Between an annual and a perennial plant, which one has shorter juvenile phase? Give reason.
An annual has a shorter juvenile phase as its entire life cycle has to be completed in one growing season within a year.
11. Name the plant that flowers once in 12 years.
Strobilanthus kunthiana (Neelakuranji). It flowered during September – October 2006 which made the hilly areas
of Karnataka, Kerala & Tamil Nadu appear as blue stretches.
12. In haploid organisms that undergo sexual reproduction, name the stage in the lifecycle when meiosis occurs?
Meiosis occurs during its post zygotic stage. As the organism is haploid meiosis cannot occur during
gametogenesis.
13. A haploid organism produces gametes by mitosis. Does it mean that meiosis never occurs in such organisms
In haploid organisms meiosis occurs during the germination of zygote because the zygote is the only diploid cell
in the life cycle of such organisms.
14. Write the chromosome number in meiocytes (2n) and gametes (n) for the following organisms.
Name of organism Chromosome number in meiocytes(2n) Chromosome number in gametes (n)
Human beings 46 23
House fly 12 6
Rat 42 21
Dog 78 39
Cat 38 19
Fruit fly 8 4
Butter fly 380 190
Ophioglossum(fern) 1260 630
Apple 34 17
Rice 24 12
Maize 20 10
Potato 48 24
onion 32 16
15. All papaya plants bear flowers but fruits are seen only in some. Why?
Papaya is a dioecious plant. Only female plants produce fruits.
16. Why is fertilization in bryophytes and pteridophytes considered as internal fertilization?
The fertilization occurs inside the archegonium of these plants.
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17. Why are meiosis & gametogenesis always interlinked?
The diploid organisms have to produce haploid gametes by meiosis to maintain diploidy through generations. So
they are always interlinked.
TWO MARKS QUESTIONS
1. Is there a relationship between the size of an organism and its life span? Justify your answer with two
examples.
There is no relationship between the size and lifespan of an organism.
Eg: The size of crow and parrot is almost same but the life span is 15years and 150 years respectively.
The Mango tree has a shorter life span compare to a Peepal tree though both are of the same size.
2. Define reproduction. What is its significance?
Reproduction is a biological process in which an organism gives rise to young ones (off springs) of its own kind.
It enables the continuity of the species generation after generation. Thus ensures the continuity of every
organism.
3. What is asexual reproduction? Mention its features.
It is a type of reproduction in which offspring are produced from a single parent without the involvement of the
formation and fusion gametes. The features are
1. Uniparental
2. Somatic cells are involved
3.It involves the production of asexual spores
4. Offsprings are genetically similar to parents
5. The rate of reproduction is faster
4. What are the differences between Zoospore & Conidium?
ZOOSPORE CONIDIUM
1. Flagellated Non – flagellated
2. Motile spores Non – motile spores
3. Formed inside sporangium (Endogenous) Formed at the tip of conidiophores.
Eg: Chlamydomonas Eg: Pencillium
5. What is regeneration? Give example.
Regeneration is a process in which the animal regrows or repairs its lost or damaged body parts.
Eg: Planaria, Star fish.
6. What is vegetative propagation? Why is it called asexual reproduction?

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Vegetative propagation is a type of asexual reproduction in plants in which the somatic cells or vegetative parts
give rise to new individuals. It is not biparental and does not involve the formation of gametes. So it is also called
asexual reproduction.
7. What are vegetative propagules? Mention them with examples.
The somatic structures of plants involved in vegetative propagation are called vegetative propagules.
Vegetative propagules Examples
Runner Grass, Gladiolus, oxalis
Rhizome Ginger, Banana
Sucker Chrysanthemum
Tuber (eyes) Potato
Offset Water hyacinth(Eichhornia),Pistia
Bulb Onion
Bulbils Agave
Epiphyllous buds Bryophyllum
Stolon Marsilea
Adventitious tuberous roots Dahlia
Stem cutting Sugarcane
8. Although potato tuber is an underground part. It is considered as a stem. Give two reasons.
1. Potato tuber has nodes & internodes
2. Leafy shoots appear from the nodes
9. Which is a better mode of reproduction, sexual or asexual? Why?
Sexual reproduction is the better mode of reproduction, because the better offspring are produced with genetic
variations. Such variations enable the organisms to survive in unfavorable conditions or adapt to changing
environmental conditions.
10. Define the following with examples
a) Oestrus cycle : The cyclical changes in the activities of ovaries & accessory ducts as well as hormones
secretion during the reproductive phase of non-primate mammals like cows, sheep, rats, deers, dogs, tigers etc.,
is called Oestrus cycle.
Monoestrus animal: Single oestrus cycle in a year. Eg: Deer.
Dioestrus animal: Two oestrus cycle a year. Eg: Dog.
Polyoestrus animal: Many oestrus cycles in a year. Eg: Mouse.
b) Menstrual cycle: The cyclical changes in the activities of ovaries & accessory ducts as well as hormones
secretion during the reproductive phase of primate mammals like monkeys, apes & humans is called Menstrual
cycle.
c) Seasonal breeders: These are the organisms that reproduce only in some favorable seasons.
Eg: Mammals living in natural & wild conditions.
d) Continuous breeders: These are the organisms that are reproductively active throughout their reproductive
phase are called continuous breeders.
Eg: Human beings.
11. The cell division involved in gamete formation is not of the same type in different organisms. Justify.
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In haploid organisms showing haplontic life cycle, gamete formation involves only mitosis. In these diploid
zygote undergoes meiosis to produce haploid organisms.
In diploid organisms showing diplontic or haplo-diplontic life cycle, gamete formation involves meiosis. In these
the zygote undergoes mitosis to produce diploid organisms.
12. Fertilization is not an obligatory event for fruit production in certain plants. Explain the statement.
Some fruits are developed from unfertilized ovary called parthenocarpic fruits. These are seedless fruits.
Parthenocarpy can be induced by spraying growth hormones. So fertilization is not an obligatory event for fruit
production. Example: grapes, pomegranate etc.
13. Define the following with examples
a) Bisexual animals or Hermaphrodites: The animals which possess both male and female reproductive organs
in the same body. Eg: Tape worm, earth worm, leech, sponges etc.,
b) Unisexual animals or homophrodites: The animals which possess male or female reproductive organs.
Eg: Cockroach, round worm, human. These exhibit sexual dimorphism.
c) Homothallic plants or bisexual or monoecious: The plant body having both male and female reproductive
structures. Eg: Fungi, Hibiscus, cucurbita, coconut, chara, sweet potato.
d)Heterothallic plants or unisexual or dioecious: The plant body having either male or female reproductive
structures. Eg: Papaya, Date palm, Marchantia
· The flowers with only stamens are called male flowers or staminate flowers.
· The flowers with only pistil are called female flowers or pistillate flowers.
14. The probability of fruit set in a self pollinated bisexual flower of a plant is far greater than dioecious plant.
Why?
In bisexual flowers, the anther and stigma lie close to each other and when the anther dehisce the pollen grains
fall on stigma and pollination is effected even in the absence of pollinator. But in dioecious plants pollinator is
necessary to bring about effective pollination.
15. Which of the following are monoecious and dioecious?
Earthworm – monoecious/hermaphrodite
Chara – monoecious
Marchantia – dioecious
Cockroach – dioecious/homophrodites
16. Both coconut and date palm produce staminate flowers. One is monoecious & the other is dioecious. Write
the difference.
Coconut palm is monoecious. It bears staminate and pistillate flowers in the same plant.
Date palm is dioecious. It bears staminate flowers in one plant & pistillate flowers in another.
17. What are the differences between Zoospore & Zygote?
ZOOSPORE ZYGOTE

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1. It is a microscopic haploid spore produced in
sporangia.
It is a diploid cell formed by the fusion of male &
female gametes.
2. It Is motile having flagella. It is non – motile, does not have flagella.
Eg: Phycomycetes, Green algae, Brown algae Eg: Sexually reproducing plants & animals.
18. Identify each part in a flowering plant & write whether it is haploid or diploid or triploid.
a) Ovary – diploid
b) Anther – diploid
c) Egg cell – haploid
d) Pollen – haploid
e) Male gamete – haploid
f) Zygote – diploid
g)Endosperm - triploid
f) Embryo sac (female gametophyte) – haploid
19. What is parthenogenesis? Name an animal that shows parthenogenesis.
The process of development of unfertilized egg into an individual is called parthenogenesis.
Eg: Formation of drones (male bees) in honey bee colony.
20. Suggest a possible explanation why the seeds in pea pod are arranged in a row whereas those in tomato are
scattered in the juicy pulp.
The pea pod is derived from a monocarpellary unilocular ovary with marginal placentation. So seeds are borne in
rows along the junction of two margins of pod.
Tomato fruit is developed from bicarpellary ovary with axile placentation. So the seeds are embedded in the
juicy pulp.
THREE MARKS QUESTIONS
1. What is sexual reproduction? Mention its features.
Sexual reproduction is a type of reproduction in which the offspring develop from the zygote which is formed by
the fusion of male and female gametes of the same individual (bisexual) or different individuals of the opposite
sex (unisexual). The features of sexual reproduction are
· Uniparental or biparental
· Formation and fusion of gametes takes place
· Off springs are not identical to parents
· Off springs show variations due to genetic recombination
· Offsprings have better chance of survival
· Rate of reproduction is slow
2. Distinguish between asexual and sexual reproduction.
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Asexual reproduction Sexual reproduction
1. Uniparental Uniparental or biparental
2. Somatic cells are involved Germ cells are involved
3.It involves the production of asexual spores It involves the formation & fusion of gametes
4. Offsprings are genetically similar to parents Offsprings are genetically dissimilar to parents
5. The rate of reproduction is faster The rate of reproduction is slower
3. Define the following. / Explain the different stages of life cycle of living organisms.
a) Juvenile phase: It is a period of growth of organism before they can reproduce sexually.
It is followed by the reproductive phase. It is called vegetative phase in plants.
b) Reproductive phase: It is a period of growth of an organisms after juvenile phase, during which the organism
undergoes morphological and physiological changes to attain sexual maturity and capable of producing
gametes.
In angiosperms, flowering marks the beginning of reproductive phase.
c) Senescent phase or old age: It is the end of reproductive phase of an organism characterized by slowed
metabolism and ultimately leads to death.
The transition of these three phases is regulated by hormones and environmental conditions.
4. Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
Higher organisms have resorted to sexual reproduction
· To ensure healthy progeny
· To produce genetically varied off springs that adapt to changes in environment & survive in all climatic
conditions.
· As it ensures the genetic recombination that results in variation which are food for evolution.
5. What are the differences between menstrual cycle & oestrus cycle?
MENSTRUAL CYCLE OESTRUS CYCLE
1. The cyclical changes in the activities of ovaries &
accessory ducts as well as hormones during the
reproductive phase of primate mammals is called
Menstrual cycle.
The cyclical changes in the activities of ovaries &
accessory ducts as well as hormones during the
reproductive phase of non-primate mammals is called
Oestrus cycle.
2. Females do not show irresistible sexual urge. Females show strong irresistible sexual urge.
3. The shedding of endometrium & bleeding occurs. Do not occur.
4. There is no heat period & copulation occurs during
any part of the cycle.
There is estrus/heat production at the time of
ovulation & copulation occurs only at that period.
Eg: monkeys, apes & humans Eg: cows, sheep, rats, deers, dogs, tigers etc.,
6. Write the differences between Gametogenesis & Embryogenesis.
GAMETOGENESIS EMBRYOGENESIS
1. It is the process of formation of gametes It is the development of embryo from zygote.
2. It includes both meiosis & mitosis. Zygotes undergo mitotic cell division & differentiation.
3. Gametes are haploid The embryos are usually diploid.
7. What are the differences between external fertilization & internal fertilization?
EXTERNAL FERTILIZATION INTERNAL FERTILIZATION

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1. The fertilization occurs outside the body of parents
in water medium.
The fertilization occurs inside the body of female in
body fluid.
2. The chances of fertilization are less. The chances of fertilization are more.
3. More number of male and female gametes are
formed.
More number of male gametes & less number of
female gametes are formed.
4. offsprings are vulnerable to predators. Offsprings are highly protected.
Eg: Bony fishes, frogs & algae. Eg: members of Plantae, reptiles, birds & mammals.
8. Write the differences between oviparous & viviparous animals.
OVIPAROUS ANIMALS VIVIPAROUS ANIMALS
1. These lay eggs These give birth to young ones.
2. The eggs are covered by hard calcareous shell. ovum are not covered by calcareous shell
3. After a period of incubation, the young ones hatch
out.
The zygote develops into young ones inside the body
of female.
4. The chances of survival of young ones are less due
to predation & unfavorable environmental conditions.
The chances of survival of young ones is more because
of proper embryonic care & protection by the mother.
Eg: Reptiles, birds. Eg: Human beings.
9. What is bisexual flower? Write common & scientific names of any one bisexual flowers.
The flower having both androecium & gynoecium is called bisexual flower.
COMMON NAME SCIENTIFIC NAME
1. Shoe flower Hibiscus rosasinensis
2. Lady’s finger Abelmoschus esculentus
3. Castor Ricinus communis
4. Brinjal Solanum melongena
5. tomato Lxcopersican esculentum
10. What is a seed? Name the plants having the largest and smallest seed.
Seed is a matured, fertilized ovule that possesses embryonic axis, cotyledon, seed coat & maybe endosperm.
Lodoicea (double coconut) is largest seed. Orchid seed is smallest seed.
FIVE MARKS QUESTIONS
1. Explain the process of asexual reproduction in amoeba and yeast cells with the help of diagrams.
Asexual reproduction in amoeba takes place by binary fission. It is the division of parental cell into two equal
halves and each half grows into an adult.
In amoeba the nucleus of the cell elongates and divides into two. This is followed by the division of cytoplasm
resulting in two equal sized daughter cells.
In yeast, the cell division is unequal and small buds are formed. They remain attached initially to the parental
cell and eventually get separated and mature into new yeast cells.
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2. Explain the events of sexual reproduction.
The events of sexual reproduction are grouped under 3 distinct stages as follows:
i) Pre-fertilization events: These are the events prior to the fusion of gametes.
They are gametogenesis & gamete transfer.
a) Gametogenesis: It is the process of formation of haploid male and female gametes.
The shape and size of the gametes vary in different organisms.
· In algae like Chlamydomonos & Cladophore the male & female gametes are similar in their shape & size
called homogametes or isogametes.
· The majority of sexually reproducing organisms produce two morphologically dissimilar gametes called
heterogametes.
· Male gamete is called sperm or antherozoid & female gamete is called ovum or egg.
The type of cell division differs during gamete formation.
· The haploid parents produce haploid gametes by mitosis.
Eg: Monera, algae, fungi & bryophytes.
· The diploid parents produce haploid gametes by meiosis.
Eg: Pteridophytes, Gymnosperms, Angiosperms & human beings.
· The diploid organisms have specialized diploid gamete producing cells called meiocytes or gamete
mother cells which undergo meiosis to produce haploid gametes.
b) Gamete transfer:
· In most of the organisms male gamete is motile & female gamete is stationary.
· But in some fungi & algae both are motile.
· In algae, bryophytes & Pteridophytes, the gamete transfer takes place through water.

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· In seed producing plants pollen grains carry male gametes & ovules carry egg cell. The pollen grains are
transferred to stigma called pollination.
· The dioecious animals have evolved some mechanisms and structures to transfer gametes for
successful sexual reproduction.
ii) Fertilization events: Fertilization is a process of fusion haploid male gamete with haploid female gamete to
produce a diploid zygote. It is also called syngamy.
There are two types of fertilization based on fertilization medium. They are,
a) External fertilization: The syngamy occurs outside the body of the parents in water medium.
Eg. Algae, fish, amphibians
b) Internal fertilization: The syngamy occurs inside the body of the female in body fluid.
Eg. Fungi, bryophytes, Pteridophytes, gymnosperms, angiosperms, cartilaginous fish, reptiles, birds and
mammals
· In animals, the motile male gametes reach the egg in accessory reproductive structures.
· In flowering plants, the non-motile male gametes are carried to egg cell by pollen tube.
iii) Post fertilization events: The events in sexual reproduction after the formation of zygote are called post
fertilization events.
a) The growth of the zygote differs in different individuals as follows.
· In algae and fungi, the zygote develops a thick wall which is resistant to desiccation and damage. It
undergoes a period of rest before germination
· In the organisms of haplontic life cycle, the diploid zygote divides meiotically to produce haploid spores
which grow into haploid individuals. Eg. Volvox, Spirogyra
· In the organisms of diplontic life cycle, the diploid zygote directly develops into a diploid individual.
Eg. Gymnosperms, Angiosperms
b) Embryogenesis: It is the development of the embryo from the zygote. During this, zygote divides mitotically
to produce a mass of cells which on differentiation forms specialized tissues and organs to form an organism.
In flowering plants, the post fertilization events include the development of
· Zygote into embryo
· Primary endosperm cell into endosperm
· Ovules into seeds
· Ovary into fruit with a thick fruit wall called pericarp
· Sepals, petals and stamens fall off
· Antipodals and synergids disappear
· Seeds after dispersal germinate into new plants under favorable conditions
OR
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Changes occur in flowering plants:
Sepal Fall off
Petal Fall off
Stamen Fall off
Zygote Embryo
Primary endosperm nucleus Endosperm (3 N)
Synergid Disintegrate
Antipodals Disintegrate
Ovary Fruit
Ovule Seed
Ovary wall Pericarp (epicarp + mesocarp + endocarp)
Integument Seed coat (testa + tegmen)
3. Fertilization leads to the formation of embryos.
a) Give the technical term for the development of embryo.
Embryogenesis.
b) What are the events that occur during embryo development?
Cell division & cell differentiation.
c) The development of the zygote depends on two factors. What are they?
Type of life cycle & environment.
d) How will you categorize animals based on the development of zygote outside or inside the female body?
Oviparous animals, Viviparous animals
e) How does zygote in fungi & algae overcome desiccation?
Zygote develops thick wall which is resistant to desiccation and damage. It undergoes a period of rest before
germination.

CHAPTER 2
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CHAPTER 2 TEACHING HOURS -10
SEXUAL REPRODUCTION IN FLOWERING PLANTS WEIGHTAGE OF MARKS - 08
CHAPTER 2
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ONE MARK QUESTIONS
1. What does the flower symbolize?
Flowers are the objects of aesthetic, ornamental, social, religious & cultural value. They have always been used
as symbols for conveying human feelings such as love, affection, happiness, grief, mourning etc.,
2. Name any one ornamental flower cultivated in homes and gardens.
(Write any one)
Carnation
Anthurium
Blue star
Cockcomb
Chrysanthemum
3. Name any one flower used in social and cultural celebration.
(Write any one)
Jasmine
Rose
Aster
Marigold
Zarbara
4. Name the tallest flower.
Amorphophallus (6ft height)
5. An anther with malfunctioning Tapetum often fails to produce viable male gametophytes. Why?
The malfunctioning Tapetum does not nourish the developing pollen grains. Thus fails to produce viable male
gametophytes.
6. Name the first cell of male gametophytic generation in flowering plants
Microspore or pollen grain is the first cell of gametophytic generation.
7. How are pollen grains preserved?
The pollen grains are preserved in liquid nitrogen at -1960
C, which are used as pollen banks in crop breeding
programs.
8. What is palynology?
It is the study of pollen grains.
9. Give an example for a plant that causes pollen allergy.
Parthenium.
10. Name the cells found at the chalazal end of embryo sac.
Antipodals.

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11. What is meant by monosporic development of female gametophyte?
The method of embryo sac formation from a single haploid functional megaspore is called monosporic
development.
12. Name the component cells of the egg apparatus in embryo sac.
Egg apparatus has two synergids and an egg cell.
13. Name the diploid nucleus of the mature embryo sac.
Secondary nucleus of the central cell
14. The meiocyte of rice has 24 chromosomes. How many chromosomes are present in its endosperm?
The endosperm will have 36 chromosomes.
15. Name the type of pollination in self-incompatible plants.
Cross pollination.
16. How does Yucca and Pronuba moth depend on each other?
The Pronuba moth deposits its eggs in the locule of the ovary of Yucca and the flower in turn get pollinated by
the moth. The larvae of moth come out of the eggs as the seed starts developing.
17. What are pollen robbers or nectar robbers?
The floral visitors or insects that consume pollen and nectar without bringing about pollination are called pollen
robbers.
18. Why do corn cobs have long tassels?
The long tassels of corn cobs are the style and stigma which help to trap the pollen grains carried by wind.
19. How do pollen grains of water pollinated plants like vallisneria protect themselves?
In water pollinated species like vallisneria, pollen grains are protected from wetting by a mucilaginous covering.
20. How does pollination occur in aquatic plants like water hyacinth & water lily?
In water hyacinth and water lily, the flowers emerge above the level of water and are pollinated by insects or
wind as in most of the land plants.
21. How is it possible in oxalis and viola plant to produce assured seed sets even in the absence of pollinators?
Oxalis and Viola plants produce cleistogamaous flowers in which anther and stigma lie close to each other that
favors self pollination and lead to assured seed sets.
22. Name the part of gynoecium that determines the compatible nature of pollen grain.
Stigma.
23. Which cell forms the kernel of coconut?
A triploid primary endosperm cell of embryo sac.
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24. How does the kernel and coconut water differ?
The kernel of coconut is cellular endosperm while coconut water is free nuclear endosperm.
25. Name the common function that cotyledon and nucellus perform.
Nourishment.
26. What are the components of embryo of a seed?
Embryo of a seed has cotyledons and embryonic axis with plumule and radical.
27. Name the fruits containing thousands of tiny seeds.
Orchid fruits and the fruits of parasitic species such as orobanche and striga.
TWO MARKS QUESTIONS
1. Name the parts of an angiosperm flower in which development of male and female gametophyte takes place.
The development of male gametophyte takes place in the microsporangium (pollen chamber) of anther.
The development of female gametophyte (embryo sac) takes place in the mega sporangium(ovule) of ovary.
2. Explain the role of Endothecium.
· Endothecium provides protection to pollen grains
· These cells are hygroscopic. When they lose water, they contract and cause dehiscence of anther for the
release of pollen grains.
3. Arrange the following terms in the correct developmental sequence: pollen grain, Sporogenous tissue,
Microspore tetrad, Pollen mother cell, Male gametes.
Sporogenous tissue à Pollen mother cell à microspore tetrad à pollen grain à male gamete
4. Identify the type of carpel in the following diagrams b and c.
b) It is multicarpellary, syncarpous pistil of Papaver
c) It is multicarpellary, apocarpous pistil of Michelia
5. Papavar and Michelia both have multicarpellary ovaries. How do they differ from each other?
The papavar ovary is syncarpous, whereas Michelia ovary is apocarpous.

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6. Name the cells that undergo meiosis in a bisexual flower
Microspore mother cell to produce haploid microspores (pollen grains)
Megaspore mother cell to produce haploid megaspore (embryo sac)
7. What is filiform apparatus? What is its significance?
The synergids have special cellular thickenings at the micropilar end called filiform apparatus. It plays an
important role in guiding pollen tube into embryo sac through synergid.
8. Name the male and female gametophytes of angiosperms.
Male gametophyte is microspore or pollen grain. Female gametophyte is embryo sac.
9. Mention the advantage and disadvantage of cleistogamaous flowers.
Cleistogamous flowers undergo autogamy so there is an assured seed set but the continued self pollination
leads to inbreeding depression.
10. What is perisperm? Give examples.
The remnants of persistent nucellus in a seed are called perisperm.
Eg: Nymphaea, Black pepper and beetroot.
11. Why do you think the zygote is dormant for some time in a fertilized ovule?
The zygote remains dormant for some time in a fertilized ovule and divides only after certain amount of
endosperm is formed from PEN, because the zygote requires reserve food materials of endosperm for the
nutrition of the developing embryo.
12. Why does the zygote begin to divide only after the division of primary endosperm cell?
The zygote needs nourishment during its development as the mature, fertilized embryo sac offers little
nourishment to the zygote. So, the primary endosperm cell divides and generates the endosperm tissue which
nourishes the zygote. Hence the zygote always divides after the division primary endosperm cell.
13. Differentiate between the following.
Hypocotyl Epicotyl
The cylindrical portion of the embryonic axis below the
level of cotyledon is called hypocotyl that terminates
in radical.
The portion of the embryonic axis above the level of
cotyledon is called epicotyl that terminates in plumule.
Coleoptile Coleorhiza
In monocot seeds, plumule is covered by a protective
sheath called coleoptiles.
In monocot seeds, radical and root cap are covered by
a protective sheath called coleorhizae.
Integument Testa
The protective envelop of the ovule is called
integument.
The outer protective seed layer is called testa.
Perisperm Pericarp
The remnants of persistent nucellus in a seed are
called perisperm.
The wall of ripened ovary or fruit is called pericarp.
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14. What are false fruits? Give example.
The fruits developed from the floral parts other than the ovary are called false fruits. Eg: Apple, Strawberry,
cashew, etc. In these fruits, the thalamus forms into the edible part.
15. What are parthenocarpic fruits? Give example.
The fruits developed from unfertilized ovary are called parthenocarpic fruits. They are seedless fruits. It can be
induced by the application of growth harmones. Eg: Banana, grape, etc.
16. Why apple is called a false fruit? Which part of the flower forms the fruit?
The fruits developed from the parts other than the ovary are called false fruits. Apple is called so because the
thalamus forms the edible part of the apple.
17. If one can induce parthenocarpy through the application of growth substances, which fruit would you select
to use parthenocarpy and why?
Parthenocarpy can be induced in banana, grapes and guava to obtain seedless fruits.
18. Are pollination and fertilization necessary in apomixes? Give reasons.
Pollination and fertilization are not necessary because in apomicts, the embryos develop directly develop from
the cells of nucellus, integument or megaspore mother cell.
19. Embryo sacs of some apomictic species appear normal but contain diploid cells. Why?
It is true that many apomicts possess normal looking embryo sacs. The only possibility of the embryo sac
possessing diploid cells is due to failure of meiotic division of megaspore mother cell. The MMC undergo mitosis
instead of meiosis to produce all diploid cells.
20. Can an unfertilized, apomictic embryo sac give rise to a diploid embryo? If yes, How?
Yes. If the embryo develops from the cells of nucellus or integument as they are diploid.
21. Name the mechanism responsible for the formation of seed without fertilization in angiosperms. Give an
example.
Apomixis Eg: grasses and members of asteraceae.
22. Are parthenocarpy and apomixis different phenomenon?
Parthenocarpy and apomixis are different phenomena. Parthenocarpy is the formation of fruits without
fertilization and hence the fruits are seedless. Whereas, apomixis is the phenomenon of formation of seeds
without fertilization. These embryos are genetically identical to the parental plant.

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23. In case of Polyembryony, if an embryo develops from synergid, and another from the nucellus, which is
haploid and which is diploid?
Synergid embryo is haploid and Nucellar embryo is diploid.
1. Explain the role of Tapetum in the formation of pollen grain.
During microsporogenesis, the Tapetum performs the following functions:
· It transports nutrients to developing pollen grains.
· It secretes enzymes (callase) and hormones.
· It produces ubisch bodies which are coated with sporopollenin to cause thickening of exine.
· Secretes oil coating over pollen grains called pollen kit. It protects the pollen from UV radiations and
attracts insects.
· Secretes special protein to recognize compatibility
2. What is the importance of pollen grains?
· Pollen grains of many species cause severe allergies and bronchial afflictions leading to chronic
respiratory disorders like asthma, bronchitis etc.,
· They are rich in nutrients. So the pollen tablets and syrups are used as food supplements.
· Consumption of pollen grains may increase the performance of athletes & race horses.
3. Write a note on viability of pollen grains.
· Viability of pollen grains depends on the prevailing temperature and humidity
· In some cereals like rice and wheat, pollen grains lose viability within 30minutes of their release
· The pollen grains of some members of Rosaceae, Leguminaceae and Solanaceae can be preserved in liquid
nitrogen at -1960
C, for many years and used as pollen banks in crop breeding programs.
4. Describe the structure of gynoecium or pistil with a neat labelled diagram.
Pistil is a female reproductive structure of flower. It has one or more units called carpels. Carpels are also called
megasporophylls. Each carpel has a basal swollen ovary, a long stalk called style that terminates in stigma.
The pistil with one carpel is called monocarpellary and with many carpels is called multicarpellary pistil.
If the carpels are fused, the condition is called syncarpous, and if the carpels are free, the condition is called
apocarpous.
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5. What are the differences between a matured unfertilized embryo sac and a fertilized embryo sac?
Unfertilized embryo sac Fertilized embryo sac
All the cells are haploid Zygote is diploid, PEN is triploid and other cells are
haploid
Antipodals and synergids are distinctly present Antipodals and synergids gradually degenerate
The haploid polar nuclei may fuse to form a diploid
secondary nucleus
Diploid secondary nucleus fertilizes with a haploid male
gamete to form a triploid PEN
Egg cell is haploid Egg cell fertilizes with the male gamete to form a
diploid zygote
6. What are chasmogamous flowers? Can cross pollination occur in cleistogamous flowers? Give reasons.
Chasmagamous flowers open at maturity and expose their anthers and stigma.
Cross pollination does not occur in cleistogamous flowers as they do not bloom or bloom after self pollination.
They are autogamous. Eg: Viola, Oxalis and Commelina
7. What are the characters of insect pollinated flowers (entamophilous flowers)?
The insect pollinated flowers are
· Large
· Colourful
· Showy
· fragrant
· rich in nectar
· provide reward in the form of nectar and pollen
· safe place to lay eggs
· some flowers produce foul odour to attract flies and beetles
· pollen grains are sticky
8. What are the characters of wind pollinated flowers (anemophilous flowers)? Give example.
· Pollen grains are light and non-sticky.
· Stigma is large & feathery to trap pollen grains.
· They have single ovule in each ovary and numerous flowers packed into an inflorescence.
Eg: corn cob & grasses.

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9. What are the characters of water pollinated (hydrophilous) flowers?Give examples
· Pollen grains are long and ribbon like
· Pollen grains are protected from wetting by mucilaginous covering
Eg: vallisneria, hydrilla, marine sea grasses like zostera
10. Explain the mechanism of pollination in water plants like vallisneria and sea grass (Zostera).
In vallisneria, the female flowers reach the surface of water by the long stalk and the male flowers are released
onto the surface of water. They are carried by water currents and some of them eventually contact with female
flowers and its stigma to bring about pollination.
In sea grass, female flowers remain submerged in water and the pollen grains are released inside the water.
Pollen grains are long, ribbon like and they are carried passively inside the water; some of them reach the stigma
and achieve pollination.
11. Write a note on pollen – pistil interaction.
All the events from pollen deposition on the stigma until the entry of the pollen tube into the ovule are together
called pollen-pistil interaction. It is a dynamic process involving pollen recognition by stigma/pistil for
compatible pollen by accepting them and if incompatible rejecting them.
· The pistil has the ability to recognize the compatible or incompatible pollen
· If the pollen is compatible, the pistil accepts the pollen and promotes post pollination events that leads to
fertilization
· This pollen – pistil interaction is governed by chemical components of pollen and pistil
12. What is self-incompatibility? Does it impose any restrictions on autogamy? Give reasons and suggest the
method of pollination in such plants.
In some plants, when mature pollen grain falls on the receptive stigma of the same flower, it fails to bring about
self-pollination. It is called self-incompatibility. Eg: Potato, Tobacco, Petunia.
It imposes restrictions on autogamy. These plants undergo only cross pollination.
13. What is artificial hybridization? How is it achieved? What is its significance?
It is a process of transferring desired pollen grains onto the stigma by preventing contamination from unwanted
pollen to obtain improved crop varieties.
It is achieved by:
· Emasculation: The technique of removal of anthers from a bisexual floral bud before their dehiscence
using a pair of forceps or scissors is called emasculation.
· Bagging: The process of covering of emasculated flowers with a bag made of butter paper to prevent
the contamination of stigma from unwanted pollen is called bagging.
Then the matured pollen grains collected from the anther are dusted onto stigma. Then the flowers are
rebagged and the fruits are allowed to develop. Plant breeders employ this technique in artificial hybridization
technique to perform crossing experiments and also to produce commercially superior varieties of plants.
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14. What is meant by emasculation? When and why does a plant breeder employ this technique?
The technique of removal of anthers from the floral bud before their dehiscence using a pair of forceps or
scissors is called emasculation.
Plant breeders employ this technique in artificial hybridization technique to perform crossing experiments and
also to produce commercially superior varieties of plants.
15. What is bagging technique? How is it useful in a plant breeding programme?
The process of covering of emasculated flowers with a bag made of butter paper to prevent the contamination
of stigma from unwanted pollen is called bagging.
· It is used to carry out cross breeding by desired pollen for crop improvement programmes.
· It is used in the production of commercially superior hybrid varieties.
16. What is triple fusion? Where does it take place? Name the nuclei involved in the triple fusion.
The fusion of one haploid male gamete with two haploid polar nuclei or one diploid secondary nucleus to
produce a triploid endosperm nucleus in the embryo sac is called triple fusion.
It occurs in the central cell of embryo sac.
The nuclei involved in triple fusion are one nucleus from male gamete and two polar nuclei.
17. Explain the development of embryo in angiosperms.
The process of development of embryo from zygote is called embryogenesis. The embryo develops from a
diploid zygote located at the micropylar region of embryo sac. The zygote development takes place after the
formation of certain amount of endosperm from PEN as it requires nourishment. The zygote divides mitotically
to form pro embryo and subsequently into the globular, heart shaped and mature embryo. The mature embryo
has cotyledon/s and an embryonic axis with plumule and radicle.
18. Write a note on viability of seeds.
· In a few species the seeds loose viability within few months.
· The seeds of large number of species live for several years.
· The oldest viable seed is that of lupine, Lupinus arcticus excavated from Arctic tundra. The seed
germinated and flowered after an estimated record of 10000 years of dormancy.
· The recent record of 2000 years old viable seed is of the date palm, Phoenix dactylifera discovered
during the archeological excavation at King Herod’s palace near ‘The Dead Sea’.

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19. What are the advantages of seeds?
· The reproductive processes like pollination and fertilization are independent of water. So the seed
formation is more dependable.
· Seeds have better adoptive strategies for dispersal to new habitats and help the species to colonize in
other areas.
· As they have sufficient food reserves, young seedlings are nourished until they are capable of
photosynthesis on their own. The hard seed coats provide protection to the young embryo.
· As they are the products of sexual reproduction, they generate new genetic combinations leading to
variations.
· Seeds are used as food by animals.
20. What is a fruit? Mention the types with example.
Fruit is a matured ripened fertilized or unfertilized ovary. It has a fruit wall called pericarp enclosing the seeds.
The types are:
a) Fleshy fruits: Pericarp is fleshy. Eg- Orange, mango, guava etc.
b) Dry fruits: Pericarp is dry. Eg- Groundnut, mustard etc.
1. Describe the LS of a typical flower with a neat labelled diagram.
Flower is a modified condensed shoot for sexual reproduction. The stalk of flower is called pedicel. The upper
swollen part of pedicel is called Thalamus. The modified leaves as floral whorls are arranged on the thalamus.
They are
· Calyx – units called sepals (for protection)
· Corolla – units called petals (to attract pollinators)
· Androecium – units called stamens (microsporophylls to produce microspores in their microsporangia)
· Gynoecium/pistil – units called carpels (megasporophylls to produce megaspores in their
Mega sporangia/ovules)
2. Explain the T.S of mature dithecous anther lobe with a neat labelled diagram.
The androecium is a male reproductive whorl of flower composed of units called stamens. The stamen has a
long narrow slender stalk called filament and a knob like bilobed anther.
The bilobed anther (dithecous) is made up of two anther lobes connected by a sterile connective. It has four
microsporangia (pollen chambers). So it is called tetrasporangiate anther lobe. Each microsporangium has a
sporogenous tissue surrounded by an anther wall made up of four wall layers. These wall layers are produced
from primary parietal cells derived from archesporial cells.
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The four layers of anther wall are:
a) Epidermis: It is outer single layer of flattened cells which provides protection.
b) Endothecium: It is present below the epidermis. It is a single layer of radially elongated cells with fibrous
thickenings. These cells are hygroscopic. When they lose water, they contract and cause dehiscence of anther
for the release of pollen grains.
c) Middle layer of cells: These are two to three layers of cells present between Endothecium and Tapetum. They
store food materials.
d) Tapetum: It is the innermost layer of anther wall containing the cells with rich cytoplasm and nuclei. It
· Nourishes pollen grains
· Forms pollen wall
· Secretes callase enzyme
· Secretes oil coating over pollen grains called pollen kit. It protects the pollen from UV radiations and
attracts insects.
The Sporogenous cells produce diploid microspore mother cells. These diploid mother cells undergo meiosis to
produce microspore tetrad. Each cell of tetrad separates to form microspore or pollen grain.
3. Explain the process of microsporogenesis (or) Explain the development of male gametophyte (pollen grain) in
flowering plants.
The process of formation of microspores or pollen grains or male gametophytes from pollen mother cell through
meiosis in the pollen chambers (micro sporangia) of anther is called microsporogenesis.
The primary hypodermal cells of young anther called archesporial cells differentiate into primary parietal cells
and primary Sporogenous cells. The primary parietal cells produce 4 layers of anther wall namely Epidermis,
Endothecium, middle layer of cells & Tapetum. Sporogenous cells develop into microspore mother cells (MMC)
or pollen mother cells (PMC). The diploid MMC undergoes meiosis to produce a haploid microspore tetrad held

CHAPTER 2
13
together by callose. Each haploid microspore separates from microspore tetrad by callase enzyme secreted by
tapetum layer.
Microspore or pollen grain is the first cell of gametophytic generation. As it produces the male gametes, it is
called male gametophyte. As the microspores develop within the microsporangium, it is called precocious
germination.
MICROSPOROGENESIS
ARCHESPORIAL CELL
SPOROGENOUS CELLS
MITOSIS
MICROSPORE MOTHER
CELL
MEIOSIS
MICROSPORE TETRAD
MICROSPORE
(POLLEN GRAIN)
4. Explain the development and structure of male gametophyte or pollen grain or microspore.
Development of male gametophyte: Microspore is the first cell of gametophytic generation. The nucleus of the
microspore migrates from center to periphery and divides to produce a large vegetative cell (tube cell) and a
small generative cell. Temporary callose wall is laid between the two cells. It dissolves by callase enzyme and the
nucleus of generative cell floats in the cytoplasm of tube cell. This two celled pollen grain is ready to liberate
from pollen sac.
Structure of pollen grain:
· It is spherical, oval, ellipsoidal & triangular in shape and 25-50 micrometer in diameter
· It has two layered wall namely outer exine & inner intine.
· Exine is hard, made up of sporopollenin. Sporopollenin is the most resistant organic material that can
withstand high temperature, strong acids, alkalis & enzymes. It has prominent apertures called germ
pores where sporopollenin is absent. Pollens can be well preserved as fossils because of the presence of
sporopollenin.
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· The intine is thin continuous layer made up of cellulose and pectin.
· It is two or three celled. One vegetative cell and one generative cell / two gametic cells.
· The vegetative cell is large with abundant food reserve (starch & unsaturated oils) and large irregularly
shaped nucleus.
· The generative cell is small and floats in the cytoplasm of vegetative cell. It is spindle shaped with dense
cytoplasm and nucleus.
· Usually the pollen grain is shed at two cell stage in 60% of the angiosperms. In the remaining species,
the generative cell divides mitotically and a three celled pollen grain is shed.
·
5. Describe the structure of an anatropous ovule or megasporangium with a neat labelled diagram.
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. The ovule has one or two protective envelopes called Integuments.
These encircle the ovule except at the tip where a small opening called micropyle is organized. The chalaza is
present opposite to the micropylar end representing the basal part of the ovule. The integuments enclose a
mass of cells with reserved food called nucellus. Nucellus encloses the embryo sac or female gametophyte.
OR
Ovule ( megasporangium) has
· Funicle – stalk of ovule
· Hilum – body of ovule that attaches to funicle
· Raphe – a ridge formed by funicle
· Integuments – covering of nucellus

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· Nucellus – a mass of thin walled parenchymetous tissue that covers embryo sac
· Embryo sac – seven celled, eight nucleated female gametophyte
· Chalaza – basal portion of the ovule from where integuments arise
· Micropyle – a small opening left at the apex of integuments
6. Explain the process of megasporogenesis and megagametogenesis (the development of female gametophyte)
(embryosac).
Megasporogenesis: The process of formation of megaspore from megaspore mother cell by the process of
meiosis is called megasporogenesis.
The process of megasporogenesis occurs in megasporangia (ovules) present inside the ovary. Each ovule has
outer integuments enclosing the nutritive tissue called nucellus. Some cells of nucellus develop into diploid
archesporial cells. The archesporial cells undergo periclinal divisions to form outer parietal layer which adds cells
to sporogenous mass during division and inner sporogenous cell that develop into megaspore mother cell
(MMC).
The MMC divides by meiosis to produce a linear tetrad of haploid megaspores. Out of 4 megaspores usually the
upper three degenerate and the lowermost towards
micropylar region enlarges to become a functional
megaspore called embryosac. (This type of development is
called monosporic development)
Megagametogenesis: It is the process of formation of egg
cell from a functional megaspore (embryo sac)
The nucleus of embryo sac divides mitotically to form two
nuclei which move to opposite poles. Two more successive
mitotic divisions occur in each nucleus resulting in eight
nucleate stage.
· Three nuclei in chalazal end are surrounded by cell wall
and organized to form three antipodal cells.
· Two nuclei from each pole move to the centre to form
polar nuclei present in a large central cell
· Three nuclei in the micropylar end are surrounded by cell
wall and organize into three celled egg apparatus. It
consists of two synergids and an egg cell.
So the mature embryo sac is eight nucleated and seven
celled.
MEGASPOROGENESIS &MEGAGAMETOGENESIS
ARCHESPORIAL CELL
MEGASPORE MOTHER CELL (MMC)
(meiosis)
FOUR MEGASPORES
(3 megaspores degenerate)
FUNCTIONAL MEGASPORE (EMBRYOSAC)
(Female gametophyte)
NUCLEUS OF EMBRYO SAC
(3 mitotic division)
8 NUCLEATED & 7 CELLED EMBRYO SAC
[3 ANTIPODALS (Chalazal end)
2 POLAR NUCLEI (Central cell)
2 SYNERGIDS + 1 EGG CELL (egg aparatus)
(micropylar end)]
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7. Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during
these events? Name the structures formed at the end of these events.
Microsporogenesis Megasporogenesis
1) The process of formation of microspores from
microspore mother cell through meiosis is called
microsporogenesis.
1) The process of formation of megaspores from
megaspore mother cell through meiosis is called
megasporogenesis.
2) It occurs inside the microsporangium of anther. 2) It occurs in nucellus of ovule.
3) Many microspore mother cells are differentiated. 3) Only one megaspore mother cell is differentiated.
4) Microspore mother cell produces tetrad of
microspores.
4) Megaspore mother cell produces a linear tetrad of
megaspores.
5) All the four cells of microspore tetrad are functional. 5) Three megaspores degenerate and only one
megaspore becomes functional and develops into
embryo sac (female gametophyte)
Meiosis occurs during these events.
Microspore and megaspore are the cells produced at the end of these two events.
8. What is pollination? Explain the types and factors favouring self pollination.
Pollination is the transfer of pollen grains from anther to receptive stigma of same or another flower.
The types are
I. Autogamy: It is the transfer of pollen grains from anther to stigma of the flowers of the same plant.
a) Homogamy – It is the transfer of pollen grains from anther to the stigma of the same flower
b) Geitonogamy: It is the transfer of pollen grain from anther of one flower to the stigma of another flower of
the same plant.
Autogamy is favored when
· Synchronisation in the release of pollen and stigma receptivity
· The flowers are bisexual
· Anther and stigma of a flower attain maturation at the same time
· Cleistogamy : The flowers do not bloom. Eg: Oxalis, Viola (common pansy) commelina
· The anther and stigma lie close to one another
II. Allogamy or cross pollination: The transfer of pollen from anther of one flower to stigma of another flower of
another plant is called allogamy.
Xenogamy: The transfer of pollen grains for anther of one flower to stigma of another flower of a different
plant. It results in genetic recombination.

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9. Mention the types of pollination based on the respective pollinating agents
TYPES OF POLLINATION I ABIOTIC AGENTS
a) Anemophily Pollination by wind
b) Hydrophily Pollination by water
II BIOTIC AGENTS
c) Zoophily Pollination by animals (lemurs, rodents, gecko, garden
lizard)
d)Ornithophily Pollination by birds (sun bird, humming bird)
e) Entamophily Pollination by insects (bees, beetles, wasps, moths)
f) Malacophily Pollination by snails
g) Myrmacophily Pollination by ants
f) Chiropterophily Pollination by bats
10. What are outbreeding devices? Explain.
The outbreeding devices are the devices or mechanisms to prevent self pollination and favor cross pollination to
overcome the problem of inbreeding depression (caused due to continuous self pollination). These are also
called contrivances for cross pollination. The factors favoring cross pollination are
· Unisexual flowers or dioecious plants or dicliny
· Male and female flowers are present in different plants which prevents homogamy and geitonogamy
Eg: Papaya
· In monoecious plants like castor and maize homogamy is prevented but not geitonogamy
· Chasmogamous flowers: the flowers with exposed anther and stigma to facilitate pollination
· Dichogamy: The bisexual flowers in which male and female reproductive parts mature at different times, so
prevents self pollination and favors cross pollination
a) Protandry: Flower in which anther mature earlier to stigma to prevent self pollination.
Eg: sunflower, cotton
b)Protogyny : Flower in which stigma matures earlier to anther to prevent self pollination
Eg: Mirabilis jalapa
· Pollen release and stigma receptivity are not synchronized due to dichogamy (protandry and protogyny)
· Herkogamy: It is flower in which there are physical barrier between anther and stigma
Eg: calotropis
· Heterostyles: The flower with different length of styles and stamens that prevents self pollination
Eg: Prim rose, Oxalis
· Self sterility or self incompatibility: The pollen grains do not germinate on stigma of same flower due to mutual
inhibition. In this the genetic mechanism prevents the pollen germination on stigma
Eg: Potato, Tobacco, Petunia.
· Suppression of one sex: In bisexual flower stamen or carpel is completely suppressed and become sterile
11. Explain the post pollination events or double fertilization process in angiosperms.
The pollen grains usually shed at two celled stage namely vegetative cell and generative cell. Further the
generative cell divides to produce two haploid male gametes in pollen tube. In some plants, the pollen grains
shed at three celled stage where pollen tube carries two male gametes from the beginning.
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After pollination, the compatible pollen grain germinates on stigma by obtaining nourishment from stigmatic
tissue. The vegetative cell or tube cell germinates into pollen tube through the style called siphonogamy. Then
the pollen tube enters the embryo sac through different regions of ovule. They are
· Chalazogamy – pollen tube enters through chalaza
· Mesogamy - pollen tube enters laterally through integuments
· Porogamy – pollen tube enters through micropyle
Normally the pollen tube enters through micropyle into the embryosac through synergids. Synergids have
filiform apparatus that guide the entry of the pollen tube into embryo sac. The tip of the pollen tube ruptures to
release two haploid male gametes into embryosac.
One haploid male gamete fertilizes with the diploid secondary nucleus of central cell to form a triploid primary
endosperm cell. This process is called triple fusion. The other haploid male gamete fertilizes with the haploid
egg cell to form a diploid zygote.
Double fertilization: In the above process one haploid male gamete fertilizes with a diploid secondary nucleus to
form a triploid primary endosperm nucleus and the other haploid male gamete fertilizes with the haploid egg
cell to form a diploid zygote (syngamy). Hence is called double fertilization.
12. Write the post fertilization events that occur in angiosperm flower.
The post fertilization events are
· Antipodals and synergids disappear
· Sepals, petals and stamens wither off
· Ovules develop into seeds
· Integuments form the seed coats namely testa and tegmen
· Primary endosperm cell develops into endosperm that provides nourishment for developing embryo
· Zygote develops into embryo
· Ovary develops into fruits
Changes occur in flowering plants:
Sepal Fall off
Petal Fall off
Stamen Fall off
Zygote Embryo
Primary endosperm nucleus Endosperm (3 N)
Synergid Disintegrate

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Antipodals Disintegrate
Ovary Fruit
Ovule Seed
Ovary wall Pericarp (epicarp + mesocarp + endocarp)
Integument Seed coat (testa + tegmen)
13. Explain the development of endosperms in angiosperms.
The endosperm is developed from triploid primary endosperm nucleus (PEN). It precedes embryo development
from zygote. During this process the triploid PEN divides mitotically to produce endosperm tissue filled with
food materials. It is used for nourishing developing embryo.
There are two types of endosperm development
· Free nuclear endosperm development: The PEN undergoes successive nuclear division to give rise to
free nuclei. This does not involve the cell wall formation. Eg: coconut water
· Cellular endosperm development: The PEN undergoes successive nuclear division followed by the cell
wall formation. Eg: White kernel of coconut
During the embryonic development, the embryo may completely consume the endosperm before the seed
matures. This results in non endospermic seeds or exalbuminous seeds. Eg: pea, ground nut, bean, etc.
The embryo may not utilize the endosperm completely and some amount of endosperm persists in the matured
seeds. This results in the formation of endospermic seeds or albuminous seeds. Eg: castor, maize.
14. Explain the structure of a typical dicot embryo with a labelled diagram.
A typical dicot embryo consists of an embryonic axis and two cotyledons. The portion of the embryonic axis
above the cotyledons is called epicotyl, which terminates with the plumule (embryonic shoot). The cylindrical
portion below the level of cotyledons is called hypocotyl, which terminates at its lower end in the radicle
(embryonic root). The root tip is covered by root cap
.
15. Explain the structure of a typical monocot embryo with a labelled diagram.
The monocot embryo possesses only one cotyledon called scutellum, which is situated towards one side of the
embryonic axis. The embryonic axis has the radicle and root cap enclosed in an undifferentiated sheath called
coleorrhiza. The portion of the embryonic axis above the level of attachment of scutellum is the epicotyl.
Epicotyl has a shoot apex and a few leaf primordial enclosed in a hollow foliar structure called coleoptile.
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20
16. Draw a VS of maize grain and LS of an albuminous seed.
17. What is a seed? Explain the structure and types of seeds.
Seed is a matured fertilized ovule. It has seed coats, cotyledon/s and an embryo. Cotyledon is thick and swollen
due to storage of food reserves. There are two types of seeds:
· Albuminous seeds: Have endosperm. Eg: Wheat, maize, barley, castor, sunflower etc.,
· Exalbuminous seeds: Do not have endosperm. Eg: Pea, groundnut etc.,
The black pepper and beet seeds have remnants of nucellus in their seeds called perisperm. The micropyle
remains a pore that facilitates the entry of water and oxygen into the seed during germination.
As the seed matures, it loses 10 – 15 % of moisture by mass and metabolic activities of the embryo slows
down. This inactive state is called dormancy. During favorable conditions like the availability of adequate
moisture, oxygen & suitable temperature induces the germination of seeds.
18. What is Apomixis (Agamospermy)? How do they develop? What is its importance?
The development of seeds without involving meiosis and fertilization is called apomixis. It is a kind of asexual
reproduction that mimics sexual reproduction.
Apomictic embryos develop from:
· Haploid gametophytes (Apogamy)
· Diploid megaspores (Apospory)
· Diploid Nucellar cell and integument cells (Adventative embryony)
The advantages of apomixis are:

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· The segregation of characters does not take place in the seeds of apomictic hybrids. This helps in conserving
desired traits of hybrids. Hence extensively used in agriculture and horticulture.
· Reduced cost of hybrid production.
· Accelerated breeding.
· Maintain hybrid vigour.
· Free from diseases.
· Nucellar seedlings of citrus provide better clones.
19. What is Polyembryony? How do they develop? How can it be commercially exploited?
Polyembryony is the occurrence of more than one embryo in a seed.
Polyembryos develop from:
• Diploid egg cells
• Haploid egg cells (Parthenogenesis)
• Secondary nucleus (Parthenogamy)
• Megaspores (Diplospory)
• Synergids & Antipodals
• Nucellar cells & Integument cells (Citrus, Mango) (Adventative embryony)
• Cleavage Polyembryony (Gymnosperms, Nicotiana)
All these embryos can be isolated and cultured in artificial medium under aseptic conditions in vitro. Through
micropropagation, many plants can be raised from one seed.
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CHAPTER -3: HUMAN REPRODUCTION
1. Define gametogenesis?
The process of formation of gametes.
2. What is insemination?
The transfer of sperms into the female genital tract.
3. What is fertilization?
Fusion of male and female gametes leads to the formation of zygote.
4. What is implantation?
Attachment of blastocyst itself to the inner uterine wall (endometrium).
5. What is gestation period?
The period of development between fertilization to parturition (child birth)
6. What is parturition?
Birth of the infant called parturition.
7. Name the pouch in which testes are present.
Scrotum.
8. Mention the significance of scrotum.
The scrotum helps in maintaining the low temperature of the testes (2–2.5o C lower than the normal
internal body temperature) necessary for spermatogenesis.
9. What are seminiferous tubules?
Seminiferous tubules are highly coiled structures present in a testicular lobule or structural and functional units
of testis.
10. What are spermatogonia?
Spermatogonia are the diploid male germ cells that give rise to spermatozoons.
11. Name the cell that provides nutrition to the male germ cells.
Sertoli cells provide nutrition to the germ cells.
12. Name the cell that secretes androgen or testosterone.
Leydig cells or interstitial cells.
13. Name the duct through which seminal vesicle opens into the urethra.
Ejaculatory duct.
14. Name the finger shaped projections of fallopian tube near the ovary.
Fimbriae.
15. Name the layer of uterus that undergoes cyclical changes or shedding during menstrual cycle.
Endometrium.
16. Name the cluster of cells in mammary lobes.
Alveoli.
17. What is spermatogenesis?
The process of formation of functional haploid male gametes or sperms in the testis of males.
18. What is spermiogenesis?
The process of conversion of haploid, non-motile and non-functional spermatids into functional motile
sperms.
19. What is spermiation?
The process of release of sperms from the seminiferous tubules.
20. Name the hormone that stimulates spermatogenesis.
LH –Luteinizing hormone.
21. Mention the function of LH?
LH acts on Leydig cells and stimulates synthesis and secretion of androgens.
22. What is semen?
The seminal plasma along with the sperms constitutes the semen.
23. What is acrosome?
The anterior portion of sperm is covered by a cap-like structure, acrosome.
24. Mention the function of acrosome?
The acrosome is filled with enzymes that help fertilization of the ovum.

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25. Name the fluid filled cavity of Graafian follicle.
Antrum.
26. What is menarche?
Menarche is the first menstrual period of young woman.
27. What causes rupturing of Graafian follicle and release of ovum?
Increased concentration of LH.
28. What is corpus luteum?
Yellow coloured body developed by the ruptured Graafian follicle .
29. What is the function of corpus luteum?
Secrete progesterone hormone
30. Name the hormone that is essential for maintenance of the endometrium.
Progesterone
31. What is menopause?
Menstrual cycles cease around 50 years of age
32. In which part of the fallopian tube does fertilization occur?
Ampullary-isthmic junction
33. What is monospermy?
Only one sperm can fertilize an ovum
34. What is cleavage?
Repeated rapid mitotic cell division of diploid zygote
35. What is morula?
The embryo with 8 to 16 blastomeres stage
36. Name the outer layer of cells in blastocyst.
Trophoblast
37. Where does the implantation of blastocyst occur?
Endometrium of the uterus
38. What is placenta?
Placenta is a connection between developing embryo and mother.
39. Name the structure that connects placenta to the embryo.
Umbilical cord
40. What is the function of umbilical cord?
It helps in the transport of substances to and from the developing embryo.
41. What are stem cells?
Stem cells which have the potency to give rise to all the tissues and organs.
42. Name the hormone produced from the ovary in later phase of pregnancy.
Relaxin
43. What is foetal ejection reflex?
Mild uterine contractions from the placenta during parturition called foetal ejection reflex
44. What is colostrum?
The milk produced during the initial few days of lactation is called Colostrum
TWO MARKS QUESTIONS
45. Name the two types of cells present on inner lining of seminiferous tubules.
Sertoli cells and gonial cells
46. Mention two female sex hormones.
FSH AND LH
47. Write any four functions of placenta.
Ø Transport of oxygen and nutrients from mother’s blood to the developing foetus.
Ø Transportation of carbon dioxide and nitrogenous wastes from the foetal blood into the mother’s blood.
Ø The storage of food materials like glycogen, fat, iron etc., All these contents are utilized by the foetus before the
formation of functional liver
Ø The transportation of antibodies from mother’s blood into the foetal blood.
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Ø It acts as a barrier and prevents the entry of microorganisms and some harmful materials like blood proteins and
sex hormones from mother’s blood into the foetal blood.
Ø It also acts as an endocrine gland and secretes several hormones like human chorionic gonadotropin (hCG),
human placental lactogen (hPL) progesterone, estrogen, and relaxin (secreted more at the later stages of
pregnancy) & helps to maintain pregnancy.
48. List the hormones that are secreted only during pregnancy in women.
Estrogen, progesterone, prolactin and thyroxin
49. List any four reproductive events in humans.
Gametogenesis, insemination, fertilization, implantation, gestation and parturition
50. Draw a neat labeled diagram of section view of ovary
51. Write diagrammatic enlarged sectional view of a seminiferous tubule showing spermatogenesis.
52. List the different parts of the male reproductive system and mention their specific function each
PARTS OF MALE REPRODUCTIVE SYSTEM FUNCTIONS
Testes Productions of sperms and male sex hormone
Epididymis Storage and maturation of sperms
Vas deferens Transportation of sperms
Ejaculatory duct Conduction of sperms
Penis Organ of copulation

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Accessory glands:
Seminal vesicle
Prostate gland
Bulbourethral gland/ Cowper’s glands
Fructose rich secretions provides energy source
Citric acid rich secretions and helps in sperm motility
Mucus rich secretions provide lubrication
53. List the different parts of the female reproductive system and mention their specific function.
PARTS OF THE FEMALE
REPRODUCTIVE SYSTEM
FUNCTIONS
Ovary Production of ova and female sex hormones
Oviduct Transportation of ova from the ovary to uterus
Uterus Site of menstruation, implantation of a fertilized ovum,
development of the foetus and labor
Cervix Secretes mucus that enhances sperm movement into uterus
and prevents the embryo from bacterial infection
Vagina Organ of sexual intercourse and birth canal
Lesser and greater vestibular glands Secrete mucus that provides lubrication during sexual
intercourse
54. Draw a neat labeled diagrammatic sectional view of mammary gland. [3/5m]
55. List the major features of embryonic developments in various
months of pregnancy?
Ø The major features of embryonic development at various months of pregnancy are;
Ø The human pregnancy lasts 9 months
Ø In human beings, after one month of pregnancy, the embryo’s heart is formed.
Ø By the end of the second month of pregnancy, the foetus develops limbs and digits.
Ø By the end of 12 weeks (first trimester), most of the major organ systems are formed, for example, the limbs and
external genital organs are well-developed.
Ø The first movements of the foetus and appearance of hair on the head are usually observed during the fifth month.
Ø By the end of 24 weeks (second trimester), the body is covered with fine hair, eye-lids separate, and eyelashes
are formed.
Ø By the end of nine months of pregnancy, the foetus is fully developed and is ready for delivery.
56. Differences between Spermatogenesis and oogenesis
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Spermatogenesis Oogenesis
1. Production of sperms called spermatogenesis
2. Spermatogenesis occurs in testis
3. Four functional sperms are produced
4. There is no formation of polar body.
5. There is no vitellogenesis
1. Production of ovum is called oogenesis.
2. Oogenesis occurs in ovary.
3. Only one functional ovum is produced.
4. Three polar bodies are produced.
5. There is vitellogenesis
57. Write diagrammatic view of male reproductive system.
58. Draw a neat labeled
diagrammatic sectional view of female reproductive
system.[5m]
59. Explain the process of oogenesis with the help of schematic representation .Oogenesis: The formation of functional
haploid ovum in the ovary by meiosis is called oogenesis.
Phases of oogenesis: It occurs in three phases.
1. Multiplication phase

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2. Growth phase
3. Maturation phase
Multiplication phase: The diploid oogonial cells of the ovarian follicles divides repeatedly by mitosis produce more
oogonium cells.
Growth phase: During this phase the diploid oogonium synthesis (yolk reserve food material) or vitelline in the cytoplasm,
increases in its size and volume to form primary oocyte. This process is called vitellogenesis.
Maturation phase: This phase involves two successive division namely meiosis I and meiosis II. The meiosis I is
reductional and produce two unequal sized cells from each primary oocyte are produced. In which one cell is smaller in
size is often called I polar body, and the other one is larger in size called secondary oocyte.
They undergo meiosis II, resulting in the formation of four haploid cells, in which one is larger in size called ootid and other
three are smaller in size called polar bodies. Finally the ootid converted into functional ovum. So at the end of
oogenesis one functional ovum and 3 polar bodies are formed. These polar bodies will not survive they undergo
disintegration.
60. Explain the spermatogenesis with the help of schematic representation.
Phases of spermatogenesis: It occurs in four phases.
1. Multiplication phase
2. Growth phase
3. Maturation phase
4. Spermiogenesis or spermateliosis
1. Multiplication phase: The diploid spermatogonial cells of the seminiferous tubules divide repeatedly by mitosis to form
number of diploid spermatogonia. Among them only few entered into growth phase and others are kept reserve.
2. Growth phase: The spermatogonium grows and increases the cell cytoplasm, volume and becomes larger called
primary spermatocytes.
3. Maturation phase: This phase involves two successive divisions namely meiosis I and meiosis II. The meiosis I is
reductional by which primary spermatocyte produce two haploid daughter cells called secondary spermocytes. These
secondary spermatocytes undergo meiosis II, which is equational. As a result four equal sized haploid cells are
produced called ‘spermatids’.
4. Spermeogenesis (spermateliosis): the differentiation of inactive, non-motile, spherical Spermatids into active, motile
and tadpole shaped sperms is called spermeogenesis.. The discharge of spermatozoans from the seminiferous
tubules called spermiation.
Schematic representation of spermatogenesis
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61. Draw a neat labeled diagram of typical sperm
62. Describe the structure of human sperm. [5m]
Structure of a typical sperm: Sperm is a male gamete produced in the testis by spermatogenesis. The sperms are
mature, haploid, microscopic, elongated and motile male gametes.
A typical sperm shows four regions. They are head, neck, middle piece and tail.
Head: Head is the anterior segment of the sperm which is oval in shape. Head includes a paternal haploid nucleus (n).
Above the nucleus cap like structure present called Acrosome, which consisting hydrolytic enzymes like acrosin,
hyalourinidase and proteinase. Acrosome helps in the penetration of sperm into ovum. Acrosome is formed by Golgi
apparatus.
Neck: It is an indistinct part connects the middle piece. It includes a proximal centriole; it lies close to the sperm
nucleus. It helps in the formation of spindle fibers in diploid zygote.

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Middle piece: It contains distal centriole. It gives rise to a long slender axial filament. Around the axial filament double
row of mitochondrial sheath is present called Neubenkern, which provides energy needed for the movement of the
sperm, hence middle piece may also be referred to as engine room of the sperm.
Axial filament is also called Axoneme and arises from the distal centriole which forms the axis of tail.
Tail: It is divided into two parts namely, main piece covered by a cytoplasmic sheath and end piece and it is naked
forms terminal part of the tail.
Human male ejects about 200 to 300 million sperms during coitus. For normal fertility at least 60% of sperms must
have normal shape and size, about 40% of them must shoe vigorous motility.
63. What is menstrual cycle? Explain the phases of menstrual cycle.
A series of rhythmical changes that take place in female reproductive system from puberty (menarche) to menopause
in woman is called menstrual cycle
Menstrual phase: it involves shedding off uterine endometrium. Hence there will be discharge of blood, tissue fluid,
mucous and epithelial cells. This phenomenon is also called menses. It lasts from about 1st to 5th day of the
cycle.
Pre-Ovulatory phase or proliferative phase: During this phase regeneration and thickening of endometrium of the
uterus occurs. It lasts from about 6th to 13th day of the cycle. During this phase, the secretion of gonadotropins (LH
and FSH) increases gradually during the follicular phase, and stimulates follicular development as well as secretion of
estrogens by the growing follicles.
Ovulatory phase: It involves the release of ovum from the Graafian follicle called ovulation. It takes place on 14th day
of menstrual cycle. During this phase, both LH and FSH attain a peak level in the middle of cycle (about 14th day).
Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge (increased concentration of
LH) induces rupture of Graafian follicle and thereby the release of ovum (ovulation).
Post Ovulatory phase or secretary phase: During this phase Graafian follicle will be converted into yellow coloured
body corpus luteum. The corpus luteum secretes large amounts of progesterone which is essential for maintenance
of the endometrium. The endometrium is necessary for implantation of the fertilized ovum and other events of
pregnancy. In the absence of fertilization corpus luteum degenerated into corpus albicans and leading to menstrual
phase. In human beings, menstrual cycles cease around 50 years of age; that is termed as menopause. Post
Ovulatory phase lasts for about 15th to 28th day of the cycle.
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CHAPTER-4
RERPODUCTIVE HEALTH
1. Define reproductive health
Healthy reproductive organs with normal functions.
OR
“A total well-being in all aspects of reproduction, i.e., physical, emotional, behavioral and social.
2. Expand the abbreviation WHO.
World health organization
3. Expand the abbreviation RCH.
Reproductive and Child Health Care programmes
4. Expand the abbreviation STD.
Sexually Transmitted Disease
5. What is amniocentesis?
Amniocentesis is a foetal sex determination test based on the chromosomal pattern in the amniotic fluid
surrounding the developing embryo.
6. Expand the abbreviation CDRI.
Central Drug Research Institute
7. Name the new oral contraceptive of female developed by CDRI.
Saheli
8. Expand the abbreviation MMR.
Maternal mortality rate
9. Expand the abbreviation IMR.
Infant mortality rate
10. What is family planning?
It is method to limit the number children's by using various contraceptives.
11. Mention the principle involved in natural method of contraception.
Avoiding chances of ovum and sperms meeting
12. What is the reason to avoid coitus from day of 14th to 17th of menstrual cycle in natural method of contraception?
Because chances of fertilization are very high during this period
13. What is lactational amenorrhea?
Absence menstruation during the period of intense lactation following parturition
14. What are diaphragms/cervical caps/vaults?
They are female contraceptive barriears inserted into female reproductive tract to cover the cervix during coitus.
15. Expand the abbreviation IUDs.
Intra uterine devices
16. Where are IUDs inserted in woman?
Uterus
17. Give an example for non-medicated IUDs.
Lippes loop
18. Give an example for copper releasing IUDs.
CuT, Cu7, Multiload 375.
19. Give an example for hormone releasing IUDs.
Progestasert, LNG-20
20. How do copper releasing IUDs prevent conception?
Suppress the sperm motality and the fertilizing capacity of sperms.

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21. How do hormone releasing IUDs prevent conception?
Make the uterus unsuitable for implantation and cervix hostile to the sperms.
22. Name “once a week” new oral contraceptive pill.
Saheli, Mala - D
23. What is sterilization?
Terminal method to prevent pregnancies
24. What is vasectomy?
Sterlization procedure in the male
25. What is tubectomy?
Sterlization procedure in the female.
26. Expand the abbreviation MTP.
Medical Termination of Pregnancy.
27. What is medical termination of pregnancy?
Intentional or voluntary termination of pregnancy before full term is called medical termination of pregnancy (MTP) or
induced abortion.
28. Expand the abbreviation RTI.
Reproductive Tract Infections.
29. Expand the abbreviation VD.
Venereal Diseases
30. Expand the abbreviation PID.
Pelvic Inflammatory Diseases.
31. What is infertility?
Couples are unable to produce children inspite of unprotected sexual co-habitation
32. Expand the abbreviation ART.
Assisted Reproductive Technologies.
33. Expand the abbreviation IVF-ET.
Invitrofertilization-Embryo Transfer
34. What is invitro fertilization?
Fertilization outside the body in almost similar conditions as that in the body.
35. Expand the abbreviation ZIFT.
Zygote intra fallopian transfer
36. Expand the abbreviation GIFT.
Gamete Intra Fallopian Transfer
37. What is artificial insemination?
Semen collected either from the husband or healthy donor is artificially introduced either into the vagina or into the
uterus.
38. Expand the abbreviation AI.
Artificial insemination
39. Expand the abbreviation IUT.
Intra uterine transfer
40. Expand the abbreviation ICSI.
Intra cytoplasmic sperm injection
41. Name the method of obtaining embryo in the laboratory by direct injection of sperm into ovum.
ICSI
42. Expand the abbreviation IUI.
Intra Uterine Insemination
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TWO MARKS QUESTIONS:
43. What are the problems of reproductive health?
Ø Myths and misconceptions about sex related aspects
Ø Improper information about reproductive organs, adolescent and the related body changes
Ø Unsafe and unhygienic sexual practices and STDs etc.,
Ø population growth
Ø sex abuse
Ø sex related crimes
44. Briefly describe the principle of working of IUDs.
Ø Increase phagocytosis of sperm within the uterus.
Ø Cu ion released suppresses sperm motility and fertilizing capacity of sperm.
Ø Hormone releasing IUDs make the uterus unsuitable for implantation and the cervix hostile to the sperm.
45. Mention the reasons for infertility.
Reasons for infertility
Ø physical
Ø congenital
Ø diseases
Ø drugs
Ø immunological
Ø psychological
46. List special techniques to control infertility /Types of Assisted reproductive technologies.
Ø GIFT, ZIFT, IVF-ET, IUI,ICSI, IUT
47. List any four sexually transmitted diseases-2m
Ø Gonorrhea
Ø Syphilis, Genital herpes
Ø Chlamydiasis
Ø Genital warts
Ø Trichomoniasis
Ø Hepatitis-B
Ø HIV
48. Mention any two symptoms of STDs.
Ø Itching, fluid discharge, slight pain, swelling in the genital region.
Ø STDs remain asymptomatic in female and remain undetected for long.
Ø In the later stage it may lead to Pelvic inflammatory diseases (PID), abortion, still births, ectopic pregnancy,
infertility or even cancer in reproductive tract.
49. List any two preventive measures of STD.
Ø Avoid sex with unknown partners/ multiple partners.
Ø Always use condoms during coitus.
Ø In case of doubt, consult with a qualified doctor for early detection.
Ø Get complete treatment if diagnosed with disease
50. What are contraceptives? Mention any four characteristics of ideal contraceptives.
Contraceptives are the devices or methods or pills to prevent conception
Characteristics of ideal contraceptive:
Ø User friendly.
Ø Easily available.
Ø Effective
Ø Reversible with no or least side – effects.
Ø No way interferes with sexual drive.

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51. Mention the strategies of reproductive health.
Ø Wide publicity to create awareness among people about reproduction related aspects;
Ø Take help of audio-visual and print media
Ø Introduction of sex education in schools to give right information about reproductive organs
Ø Avoid misconceptions and myths regarding sex related aspects.
Ø Proper information regarding sex organs, adolescent stage and hormonal changes in the body
Ø Giving knowledge about safe and hygienic sexual practices
Ø Knowledge about unsafe sex and sexually transmitted diseases.
52. How educating couples or those in marriageable age group to maintain the healthy family of desired size?
Ø Available birth control options
Ø Care of pregnant woman
Ø Postnatal care of the mother and child
Ø Importance of breast feeding
Ø Equal opportunities for the female and male child
Ø Statutory ban on amniocentesis.
53. Write a note on intra uterine devices and mention the types.
Ø The devices are only used by female.
Ø Inserted by doctor or by expert nurses in the uterus through vagina.
Ø Non-medicated IUDs e.g. Lippies loop.
Ø Copper releasing IUDs (CuT, Cu7, Multiload 375)
Ø Hormone releasing IUDs (Progestasert, LNG-20)
54. Explain any five birth control/contraceptive methods.
[REFER TEXT BOOK FOR DETAILED ANSWER]
Natural methods:
Ø Periodic abstinence: avoid fertile period
Ø Withdrawal or coitus interruption
Ø Lactational amenorrhea
Barrier methods:
Ø condoms-male and female
Ø Diaphragm-female contraceptive
Ø Cervical caps and vaults
Intra uterine devices
Oral contraceptives
Injections or implants
Emergency contraceptives
Surgical methods
Oral contraceptives:
This method is used by female only.
Ø Used in the form of tablets hence popularly called pills.
Ø Pills contain progestogens or progesteron-estrogen combination.
Ø Pills have to be taken daily for a period of 21 days.
Ø Started within first five days of menstruation.
Ø Pills are very effective with lesser side effect.
Ø Saheli- a non steroidal preparation used as oral contraceptive pills.
Principle of working of oral pills:
Ø Inhibit ovulation.
Ø Inhibit implantation.
Ø Alter the quality of cervical mucus to prevent/retard entry of sperms.
Injections or implants
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Ø Progestogens alone or in combination with estrogen are used as injections or implants under the skin by female.
Ø Mode of action is similar as in pills
Ø It is very effective for long periods.
SURGICAL METHODS-
Ø Tubectomy
Ø vasectomy
Ø MTP
55. Explain briefly any five assisted reproductive technologies to overcome from infertility problems.
The most recent line of treatment for infertility involves the use of several progressive techniques, which are collectively
known as assisted conception or assisted reproductive technologies (ART).
The couples could be assisted to have children through some special techniques like IVF and ET, GIFT, ZIFT, IUT, ICSI.
Ø IVF and ET – Invitro fertilization and Embryo transfer: Popularly called test tube baby programme.
Ø Fertilization taken place outside the female body means in the lab i.e., in the test tube called invitrofertilization.
Ø GIFT- Gamete intra-fallopian transfer technique: the healthy ova and potent sperms are introduced into the upper
part of the fallopian tube, where fertilization takes place.
Ø ZIFT-Zygote intra-fallopian transfer technique: In this method, after invitro fertilization, the zygotes are transferred
into the fallopian tube.
Ø IUT( intra uterine transfer): Embryos with more than 8 blastomeres, into the uterus, to complete its further
development.
Ø ICSI (Intra cytoplasmic sperm injection): It is another specialized procedure to form an embryo in the laboratory in
which a sperm is directly injected into the ovum.
Ø AI (Artificial insemination): Infertility cases either due to inability of the male partner to inseminate the female or
due to very low sperm counts (oligospermia) in the ejaculates, could be corrected by artificial insemination
technique
Ø IUI (Intra-uterine insemination): In this technique, the semen collected either from the husband or a healthy donor
is artificially introduced either into the vagina or into the uterus of the female.

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Chapter-6
MOLECULAR BASIS OF INHERITANCE
I ONE MARKS QUESTIONS
1. Name the nitrogen base present in DNA, but absent RNA.
ANS - Thymine
2. Define transcription.
ANS- the process of synthesis of mRNA from DNA by enzymes
3. What are purines / pyrimidines?
ANS - Double ring nitrogen base called purines. Ex- A& G
Single ring nitrogen base called purines. EX- C, T & U.
4. Name the bond linked between nitrogenous base & sugar.
ANS – N – glycosidic linkage
5. What is polynucleotide chain?
ANS- more than 5 nucleotide are join end to end to form chain called polypeptide
chain.
6. Who elucidate the structure of DNA?
ANS- Watson & crick
7. Define Erwin Chargaff rule.
ANS – amount of purines are equal to Pyrimidines.
8. Define central dogma.
ANS - flow of genetic information from DNA to RNA to polypeptide or protein.
9. What is nucleosome?
ANS- The negatively charged DNA is wrapped around the positively charged
histones octomer to form a structure called nucleosome
10. What is replication?
ANS – DNA produce an exact copy of itself called replication.
11. What is RNA splicing?
ANS – The introns are removed & exons are joined in a definite order
12. How many sensible codons in genetic code dictionary?
ANS - 61
13. UAA, UAG & UGA are called Nonsense codon, why?
ANS – these codons do not code for any amino acids.
14. What is mutation?
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ANS- the alteration of DNA sequences results in changes in the genotype &
phenotype of an organism.
15. Define DNA finger printing.
ANS- an analytical technique, sequence of DNA repeats to Identify of individual at
DNA level is known as DNA finger printing
16. Define bioinformatics.
ANS- the management & analysis of the biological information stored in the
databases using computers.
17. In a double strand DNA the percentage of Adenine (A) is 15%. Calculate the % of
Guanine (G).
ANS – 35%
II TWO MARKS QUESTIONS
1. Nucleosome composed off?
Histones octomer & DNA
2. Name the amino acids residue carry positive charge of histones.
Lysines & arginines
3. Mention 4 properties of genetic material.
i. Undergo replication
ii. Chemically & structurally be stable
iii. Slow changes (mutation) that are required for evolution.
iv. Able to express itself in the form of ‘ Mendelian Characters’
4. Differentiate template strand & coding strand.
One of the DNA strand act as template to produce mRNA called template strand.
The DNA strand which does not code for anything is referred as coding strand
5. Write the function of DNA- dependent RNA polymerase & RNA- dependent DNA
polymerase.
DNA- dependent RNA polymerase - synthesis of mRNA, dependent on DNA strand
RNA- dependent DNA polymerase - synthesis of DNA, dependent on genetic RNA
strand.
6. What are exons & introns?
The coding sequences or expressed sequence of mRNA called Exons.

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The non coding sequence of mRNA called introns.
7. What is capping & tailing?
Unusual nucleotide (methyl Guanosine triphosphate) is added to the 5’ – end of
hnRNA called capping
Adenylate residue (200-300) are added at 3’– end called tailing
8. Mention the two essential role of ribosome during translation.
i. Synthesizing polypeptide chain or protein
ii. Act as catalyst for the formation of polypeptide bond.
9. Differentiate between Repetitive DNA & satellite DNA.
Unusual base pairs sequence (10-15) repeated many times in DNA called
Repetitive DNA. (It varies from person to person, but unique to a person)
The small peaks are separated from bulk DNA during DNA finger printing called
satellite DNA.
10. Mention the application of DNA finger printing.
i. Solving disputed parentage
ii. To identify criminals & rapists
iii. Reuniting the lost children
iv. Immigrant dispute
v. To establish the identity of dead bodies.
III THREE MARKS QUESTIONS.
1. Name the three component of nucleotide.
Nitrogen bases. Pentose sugar & phosphate groups.
2. Draw a schematic structure of a transcription unit.
3. Where do you find code, codon & anticodon?
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Code - DNA
Codon - mRNA
Anticodon - tRNA
4. Mention the function of RNA polymerase I, II & III.
RNA polymerase I - Transcribe rRNA
RNA polymerase II - Transcribe precursor of mRNA
RNA polymerase III - Transcription of tRNA, 5srRNA & snRNAs
5. What are the goals of HGP?
i. Mention a Identify genes in human DNA
ii. Determine the sequence of human DNA
iii. Store information in databases.
iv. Improve data analysis
6. Mention any three level of regulation of gene expression.
i. Transcriptional level
ii. Splicing level
iii. Translational level
IV FIVE MARKS QUESTIONS
1. Explain the structure of Watson & Crick model of structure of DNA.
In 1953 James Watson and Francis Crick, based on the X-ray diffraction data produced
by Maurice Wilkins and Rosalind Franklin, proposed a very simple but famous Double
Helix model for the structure of DNA.
i. The backbone of DNA strand composed of repeated units of sugar and phosphate
molecules.
ii. The pairing of nitrogen bases are always between a specific purins and specific
pyrimidines that is between A and T, G and C and vice versa. This type of base
pairing is called complementary base pairing.
iii. Due to complementary base pairing the amount of purines and pyrimidines in DNA
are equal. The ratios between Adenine and Thymine, Guanine and Cytosine are

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constant and equals to one (That is amount of A=T, and G=C) this is called
Chargaff’s rule of base equivalence.
iv. The bases in two strands are paired through hydrogen bond (H – bonds) forming
base pairs (bp). There are two hydrogen bonds between A and T, three hydrogen
bonds between G and C.
v. The two chains are coiled in a right –handed fashion.
vi. The pitch of the helix is 3.4 nm or 34 Å & there are roughly 10 bp in each turn.
vii. Double stranded DNA molecule has a diameter of 20Å and distance between two
successive base pairs is 0.34nm (3.4 Å).
viii.The plane of one base pairs stacks over the other in double helix. This in addition
to H – bonds, confers stability of the helical structures.
2. With labeled diagram explain packaging of DNA helix.
The human DNA in a cell contains 6.6 × 109 base pairs and its length is about 2.2
meters (6.6× 109x0.34x109m/bp). It is greater than the dimension of the nucleus (106).
The long polymer DNA is present in highly folded or packed form in the nucleus.
In prokaryotes the negatively charged DNA held with some positively charged proteins
in a region called nucleoid. Thus DNA forms large loops held by proteins in
prokaryotes.
In eukaryotes
· A positively charged protein called histones held with DNA.
· Histones contain amino acids lysine and arginines residues that carry positive
charges in their side chains.
· Eight histones molecules are organized to form a structure called histone
octomer.
6 | P a g e
· The negatively charged DNA is wrapped around the positively charged histone
octomer to form a complex called nucleosome.
· A typical nucleosome contains 200 bp of DNA helix.
· Nucleosomes constitute the repeating unit of a structure in nucleus called
chromatin. The nucleosomes in chromatin are seen as ‘ beads –on –string’
The chromatin fibers are further coiled and condensed at metaphase stage of cell division to
form chromosomes. The packaging of chromatin at higher level requires additional set of
proteins called Non-histone Chromosomal (NHC) proteins. In a typical nucleus, some
regions of chromatin are loosely packed and lightly stained called euchromatin. The highly
coiled and darkly stained regions of chromatin are called heterochromatin. Euchromatin is
said to be transcriptionally active chromatin, whereas heterochromatin is inactive.
3. Explain Griffith transforming principle to search for genetic material.
Frederick Griffith showed transformation in the bacterium Diplococcus
pneumoniae which cause pneumonia disease in mammals.
This bacterium (Diplococcus pneumonia) is found in two forms or strains as
Smooth Strain (S) and Rough strain (R). The S strains are with mucous (polysaccharide)
coat and pathogenic hence called Virulent Strains. The R Strains are without mucous coat
and non-pathogenic called avirulent strains.
Griffith showed that injections of S-strains into mice produce Pneumonia disease.
But an injection of R-strains does not produce the disease. The heat killed S-strains does
not produce the disease. But the mixture of live R-strains and heat killed S-strains produce
the disease in mice. Griffith recovered S-strains of bacteria from the dead mice.

7 | P a g e
S strain ——-> Inject into mice ——> Mice die
R strain ——–> Inject into mice ——-> Mice live
Heat killed-S strain ——-> Inject into mice ——> Mice live
S strain (heat killed) + R strain (live) ——–> Inject into mice ——-> Mice die
Griffith concluded that some transforming principle transferred from the heat killed S-strains
to produce mucous coat in R-strains and they become virulent. The transforming principle is
genetic material, But he fail to define biochemical nature of it through his experiments.
(However, the biochemical nature of genetic material was not defined from his
experiments).
4. Explain semi conservative replication of DNA.
The replication occurs during S-phase of Interphase during cell cycle. The process
of replication is proved qualitatively by J.Herbert Tayler and quantitatively by Meselson
and Stahl.
Requirements:
8 | P a g e
• Four types of nucleotides of DNA
• Energy source (ATP)
• RNA primers
• Inorganic ions:- Mg+2
• Enzymes: a) Topoisomerases: - Breaking and
(DNA Gyrases) resealing DNA strand.
b) Helicases: - Unwinding DNA helix
C) DNA Polymerase I, II and III - Catalyze replication
d) RNA Primase: - Synthesize RNA primers
e) DNA Ligase: - Join DNA fragments.
The main enzyme is referred to as DNA –dependent DNA polymerase. The average rate
of polymerization has to be approximately 2000 bp per second.
Mechanism: The process of replication involves the following steps.
a. Activation of nucleotides:
The nucleotides of DNA such as d-AMP, d-TMP, d-GMP and d-CMP are activated
and phosphorylated by ATP in to d-ATP, d-TTP, d-GTP and d-CTP respectively.
b. Unwinding of DNA helix:
The initiation of replication or uncoiling of the DNA helix starts at a specific point
called origin of replication or Ori. There is a single Ori in prokaryotes but many Ori are
present in eukaryotes.
The unwinding of DNA strands is catalyzed by Helicases. DNA Gyrases
(Topoisomerases) remove the coils that accumulate in front of the replication fork. The
separation of DNA strands during the initiation of replication forms a Y-shaped structure
called replication fork. The separated DNA strands act as master strands or template
strands for the formation of new strands.
c. Formation of RNA-primer:

9 | P a g e
The synthesis of new strand always proceeds in 5'"3' direction. During the initiation
of replication a short segment of RNA is synthesized with the help of an enzyme RNA
primase called RNA primer.
d. Initiation and elongation of DNA strand:
The DNA nucleotides are now added to exposed bases of parental DNA strand from
the end of RNA primer. This process is catalyzed by DNA Polymerase III and Mg+2. The
addition of nucleotides of DNA proceeds only in 5'"3' direction. The two new strands of
DNA produced in opposite or antiparallel direction called bidirectional replication.
In one strand the synthesis of new DNA strand goes on continuously in 5'"3'
direction and this new strand is called leading strand. In the opposite strand (3'"5') the
addition of nucleotides proceeds as short segments away from the replication fork called
lagging strand. The short single stranded fragments of DNA of the lagging strand are called
Okazaki fragments. The lagging strand has many RNA primers.
Later the RNA primers are removed and replaced by DNA nucleotides by an enzyme
DNA polymerase I. The Okazaki fragments are joined by DNA Ligase enzyme.
e. Termination of replication:
The termination of replication is signaled by specific sequence of DNA nucleotides.
After replication the DNA polymerase II takes an editing role to remove abnormal nitrogen
bases and incorporate the normal bases (proof reading). This process is called genetic
repair mechanism. (In E.coli the replication of DNA completes in 38 minutes. The average
rate of polymerization is approximately 2000 base pairs per second. It contains 4.6x106
bp.)
5. Explain the process of transcription
The process of copying genetic information from one strand of the DNA into RNA is
called transcription. (The biosynthesis of RNA from DNA is called transcription.)
10 | P a g e
i. The transcription unit of DNA consists of three regions as a promoter, structural
gene and a terminator.
ii. The transcription begins by the uncoiling of DNA strands due to the breakage of
hydrogen bonds.
iii. After the unwinding DNA dependent RNA polymerase is only capable of catalyzing
the process of elongation in association with initiation – factor (σ). It binds to
promoter and initiate transcription.
iv. One of the strand of DNA (3'"5' strand) act as a template to produce RNA by
complementary base arrangement is called antisense strand
v. The strand of DNA which bears the same sequence as the RNA and not used as
template during transcription is called sense strand or coding strand.
vi. The nucleotides of RNA are attracted and assembled complementary to template in
the presence of DNA dependent RNA-polymerase and Mg+. Only a short stretch of
RNA remains bound to the enzyme.
vii. The termination of RNA chain is brought about by certain terminator sequences on
DNA & termination factor (ρ).
viii.Finally the new RNA formed and RNA-polymerase gets detached from the DNA.
Again the two strands of DNA rewind by the hydrogen bonds.

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