Extra Questions for Class 12 Biology Chapter 1 Reproduction in Organisms
Q.1. Is Marchantia monoecious or dioecious? Where are the sex organs borne in this plant?
Ans. Marchantia is dioecious. The male sex organs, antheridia, are borne on the antheridiophores and female sex organs, called as archegonia are borne on archegoniophores.
Q.2. Meiosis is an essential event in the sexual life cycle of any organism. Give two reasons.
Ans. (i) Meiosis helps in the formation of gametes by reductional division and maintains constant
number of chromosomes.
(ii) Meiosis brings variation in off-springs by recombination of genes.
Q.3. Write the two pre-fertilization events from the list given below:
Syngamy, Gametogenesis, Embryogenesis, Pollination
Ans. Gametogenesis, Embryogenesis, Pollination.
Q.4. Name an organism where cell division is itself a mode of reproduction.
Ans. Protists/Monerans/Amoeba/Paramecium (any unicellular organism).
Q.5. State the fate of a pair of autosomes during gamete formation.
Ans. During gamete formation a pair of autosomes segregate from each other.
Q.6. Rearrange the following events of sexual reproduction in the sequence in which they occur in a flowering plant: embryogenesis, fertilisation, gametogenesis, pollination.
Ans. Gametogenesis, pollination, fertilisation, embryogenesis.
Q.7. Name the group of organisms that produce non-motile gametes. How do they reach the female gamete for fertilisation?
Ans. Angiosperms produce non-motile gametes. They reach the female gamete with the help of air or water.
Q.8. In yeast and Amoeba the parent cell divides to give rise to two new individual cells. How does the cell division differ in these two organisms?
Ans. In Amoeba, binary fission takes place whereas in yeast cell division occurs by budding.
Q.9. Mention the site where syngamy occurs in amphibians and reptiles, respectively.
Ans. In amphibians, external fertilisation occurs hence, syngamy occurs in the medium of water. In reptiles, internal fertilisation occurs hence, syngamy occurs within the body of female parent.
Q.10. Name two animals that exhibit oestrus cycle.
Ans. Cow, sheep and rat (Any two).
Q.11. How is it possible in Oxalis and Viola plants to produce assured seed-sets even in the absence of pollinators?
Ans. By presence of cleistogamous flowers, hence anthers and stigma lie close to each other ensuring self-pollination.
Q.12. Mention the unique feature with respect to flowering and fruiting in bamboo species.
Ans. Bamboo species flower once in its life time generally after 50–100 years of vegetative growth. It produces large number of fruits and then dies.
Q.13. Cucurbits and papaya plants bear staminate and pistillate flowers. Mention the categories they are put under separately on the basis of the type of flowers they bear.
Ans. Cucurbit is a monoecious plant having staminate and pistillate flowers on the same plant. Papaya has staminate and pistillate flowers on separate plants and hence it is dioecious.
Q.14. Why is banana considered a good example of parthenocarpy?
Ans. In banana, formation of fruit occurs without fertilisation, and thus there is no formation of seeds.
So, it is considered a good example of parthenocarpy.
Q.15. At what state does the meiosis occur in an organism exhibiting haploidic life cycle and mention the fate of the products thus produced.
Ans. Organisms exhibiting haploidic life cycle undergo meiosis during zygote formation. The products thus formed are haploid gametophyte.
Q.16. Name the phenomenon and one bird where the female gamete directly develops into a new organism.
Ans. The phenomenon is called parthenogenesis. Turkey is the name of the bird.
Q.17. Give reasons for the following:
Some organisms like honey-bees are called parthenogenetic animals.
Ans. Since drones/males develop from unfertilised eggs so they are called as parthenogenetic animals.
Q.18. Mention the unique flowering phenomenon exhibited by Strobilanthus kunthiana (Neelakuranji).
Ans. Strobilanthus kunthiana flowers once in 12 years.
