1. Reproduction In Organism.
Exercises
• 1. Why is reproduction essential for
organisms?
• Reproduction is essential to the organisms for
continuity of life on earth.
• 2. Which is a better mode of reproduction:
sexual or asexual? Why?
• Sexual reproduction is better.
• Because the progeny of sexual reproduction
varies from parents. This helps to evolution.

2. • 3. Why is the offspring formed by asexual
reproduction referred to as clone?
• Because the offsprings formed by asexual
reproduction are genetically identical to their
parents.
• 4. Offspring formed due to sexual reproduction
have better chances of survival. Why? Is this
statement always true?
• In sexual reproduction, genetic variation occurs
among the offsprings, which may adapt better
with the environment.
• Hence the statement is true for maxium.

3. • Q.5.How does the progeny formed from asexual
reproduction differ from those formed by sexual
reproduction?
• Progeny from asexual reproduction have similar
genetic make up and are exact copies of their
parents, i.e., clone of the parent.
• Variation is absent.
• Progeny is less adaptable to changes in
environment.
• Progeny from sexual reproduction have different
genetic make up and are dissimilar to the parent.
• Variation occurs in progeny.
• Progeny is more adaptable to changes in
environment.

4. • Q.6. Distinguish between asexual and sexual
reproduction. Why is vegetative reproduction
also considered as a type of asexual
reproduction?
• Ans. Vegetative reproduction is considered as a
type of asexual reproduction because:
• single parental involves in reproduction.
• There is no formation of gametes.
• Vegetative progeny from are somatic cells.

5. • Q.7. What is vegetative propagation? Give two
suitable examples.
• Ans. In plants, the asexual reproduction which is
capable of producing new offsprings is called
vegetative propagation.
• Examples:
1. Runner or stolon: in strawberry slender stem that
grows horizontally to ground is called runner.
Naturally it cut off and separated develops in to
new individual.
2. Rhizome: In Ginger modified underground stem
forms rhizome. If it separated into pieces, each
piece give rise to a new plant.
3. Tuber: Potato tuber having buds when grown,
develops into a new plant.

6. • Q.8. Define (i) Juvenile phase,
(ii)Reproductive phase,
• (iii) Senescent phase.
• Ans. (i) The period of growth to attain
maturity is called juvenile phase
• (ii) Reproductive phase is the phase in the life
cycle, where organisms possess all the
capacity reproduce sexually.
• (iii) The end of reproductive phase in which an
organism slowly loses the rate of metabolism,
reproductive potential and dies up.

7. • Q. 9. Higher organisms have resorted to sexual
reproduction in spite of its complexity. Why?
• Ans. Higher organisms have resorted to sexual
reproduction to
1. To introduce variation to enable better adaptive
capacity.
2. To restore vigour and vitality of the race.
3. To get proper parental care during.

8. • Q. 10. Explain why meiosis and
gametogenesis are always interlinked?
• Ans. Gametogenesis (formation of male and
females gametes) is associated with reduction
in chromosome number.
• Thus gametogenesis is interlinked with
meiosis because in meiosis, reduction of
chromosome number from diploid set (2n) to
haploid set (n) takes place.

9. • Q. 11. Identify each part in a flowering plant and write
whether it is haploid(n) or diploid (2n).
• (a) Ovary --------- Diploid
• (b) Anther -------- Diploid
• (c) Egg ------------- Haploid
• (d) Pollen ---------- Haploid
• (e) Male gamete --- Haploid
• (f) Zygote. ----------- Diploid

10. • Q. 12. Define external fertilisation. Mention its
disadvantages.
• Ans. The fusion of gametes outside the body of
an organism is called external fertilisation, e.g.,
in frog.
• Disadvantages of external fertilisation:
1. It requires a media (water) for fusion of
gametes.
2. Organism produces large number of gametes.
3. The predators destroys eggs and offsprings.
4. Less or no parental care is taken to young one.
5. The survivality rate of offspring to adult is less

11. Q.13. Differentiate between a zoospore and a zygote.
• Zoospore:
• (i) These are asexually
produced unicellular,
naked and motile
spores having one or
two flagella.
• (ii) It may be haploid or
diploid.
• (iii) Zoospore takes part
in dispersal.
• Zygote:
• (i) Zygote is diploid cell
formed by fusion of
male and female
gametes.
• (ii) It is always diploid.
• (iii) Zygote do not have
significant role in
dispersal.

12. Q. 14. Differentiate between gametogenesis from
embryogenesis.
• Gametogenesis
• (i) The formation of
gametes from meiocytes
(gamete mother cell).
• (ii) This is a pre-
fertilisation event.
• (iii) The cell division
during gametogenesis is
meiotic.
• (v) It produces haploid
gamete.
• Embryogenesis
• (i) The formation of
embryo from zygote cell.
• (ii) This is a post-
fertilisation event.
• (iii) The cell division
during embryogenesis is
mitotic.
• (v) It gives rise to diploid
embryo.

13. • Q. 15. Describe the post-fertilisation changes in a
flower.
• After zygote formation, the sepals, petals and
stamens of flower falls off.
• In some plants like tomato, brinjal sepals persist
with fruit.
• The zygote develops into embryo.
• The ovule develops into seed.
• The ovary matures and develops into fruit
(pericarp).

14. • Q. 16. What is a bisexual flower?
• A flower which possess both the male and female
reproductive structures, i.e., both stamen and
carpel is called a bisexual flower.
• Q. 17. Examine a few flowers of any cucurbit
plant and try to identify the staminate and
pistillate flowers. Do you know any other plant
that bears unisexual flowers?
• Ans. A staminate or male flower has only stamens
and no carpel. A pistillate flower has only carpel
and no stamens.
• Plants that bear unisexual flowers are papaya
and date palm.

15. • Q. 18. Why are offspring of oviparous animals at a
greater risk as compared to offspring of viviparous
animals?
• Ans. In viviparous animals, the young one develops
inside the body of the female organism. As a result
of this, the young one gets better protection and
nourishment for proper development.
• In oviparous animals, they lay egg and the young
one develops outside the body of the female.
1. The predators destroys eggs and offsprings.
2. Less or no parental care is taken to young one.
3. The survivality rate of offspring to adult is less