Bihar Board - Class 12 Biology - Chapter 1: Reproduction in Organisms Short Answer Question

Class 12th Bihar Board chapter Reproduction in Organisms explain the biological process by which organisms produce offspring, ensuring species continuity. Vidyakul provides comprehensive study material, including short-questions-answers to enhance understanding and exam preparation effectively.

Chapter- 1

Reproduction in organisms

Short Answer type

Question 1.  Why is reproduction essential for organisms?

Ans: Reproduction is the ability of living organisms to produce a young one similar to itself. It ensures continuity of a species generation after generation. Reproduction introduces variation in the organisms. Useful variations are essential for adaptation and evolution. Therefore, it is essential for organisms.

Question 2. In Vivipary, how the developing embryos are nourished?

Answer: In Vivipary, the embryo develops inside the womb of the female's body, hence they are nourished by the mother through the placenta.

Question 3. How Charles Bonnet and Abraham Trembley contributed to the Biological field?

Answer: Charles Bonnet discovered the process of parthenogenesis. Abraham Trembley was the first to study the concept of Regeneration in the Hydra

Question 4.Meiosis is a type of cell division where the chromosome number is reduced to half the number of daughter cells. Which type of cellular division occurs in the drones to produce spermatozoa? Why?

Answer: The gonadal cells of drones undergo mitosis to form sperms. Because the drones are haploid in nature since they develop from unfertilized eggs. To avoid further reduction in chromosome no. and maintain the chromosomal constancy, (instead of undergoing meiosis), mitosis will take place leading to formation of haploid gametes.

Question 5 Name the phenomenon where the female gamete directly develops into a new organism with an avian example.

Answer: Parthenogenesis is the phenomenon where the unfertilized female gamete (egg) develops into a new individual, e.g. Turkey

Question 6. What is parthenogenesis? Give two examples from animals.

Answer: The development of an egg into a complete individual without fertilization is known as parthenogenesis. It was first discovered by Charles Bonnet in 1745.
E.g. Honey bees, Aphis.

Question 7.Which type of reproduction is effective – Asexual or sexual and why?

Answer: Sexual reproduction is highly effective than asexual reproduction since the offspring produced are genetically different from parents causing variations. Variation leads to evolution.

Question8. The unicellular organisms which reproduce by binary fission are considered immortal. Justify.

Answer: In unicellular organisms during binary fission, the entire cell (organism) divides completely to form two daughter cells which later on develop into adults and the process goes on repeatedly during each division leading to the immortality of the cell (organism). Hence unicellular organisms like amoeba are ‘biologically immortal’.

Question 9. Why is the offspring formed by asexual reproduction referred to as a clone?

Answer: Offsprings developed by asexual reproduction are referred to as clones since they are genetically & morphologically similar to this parent.

Question 10. Why are the offsprings of the oviparous animals at a greater risk as compared to offsprings of viviparous organisms?

Answer: Oviparous animals are egg-layers. The eggs containing embryos are laid out of their body and are highly susceptible to environmental factors (temperature, moisture etc.) and predators. Whereas, in viviparous animals, the embryo develops inside the body of female and comes out as young ones. Hence offsprings of oviparous animals are at risk compared to viviparous animals.

Question 11 Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?

Ans: Higher organisms have resorted to sexual reproduction in spite of its complexity because sexual reproduction results in multiplication and perpetuation of species and also contributes to evolution of species by introducing variation much faster than asexual reproduction in a particular population. Sexual reproduction enables higher organisms to survive during unfavorable conditions.

Question 12.  Explain why meiosis and gametogenesis are always interlinked?

Ans: Gametogenesis is the process of formation of two types of haploid gametes (male and female). In gametogenesis, gametes are haploid in number and formed by meiosis so the chromosome number is haploid. Thus gametogenesis is always linked with meiosis.

Question 13. Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n).

(a)Ovary ————————

(b)Anther ————————

(c)Egg ————————

(d)Pollen ————————

(e)Male gamete ————————

(f)Zygote ————————

Ans: (a)2n

(b)2n

(c)n

(d)n

(e)n

(f)2n

Question 14. What is Incomplete parthenogenesis? Explain with examples.

Answer: Incomplete parthenogenesis is a type of reproduction in which both sexual reproduction and parthenogenesis occur. Example: In honey bees, the fertilized eggs develop into queen bees and worker bees, whereas the unfertilized eggs develop into drones (male).

Question 15. Explain briefly the nature of Ovovivipary.

Answer -In Ovoviviparous animals, the embryo develops inside the egg and remains in the mother’s body until they are ready to hatch. This method of reproduction is similar to viviparity but the embryos have no placental connection with the mother and receive their nourishment from the egg yolk. Ovoviviparity is seen in fishes like sharks.

Question 16. Point out any six modes of asexual reproduction seen in animals.

Answer:

1. fission
2. budding
3. fragmentation
4. sporulation
5. regeneration
6. gemmule formation.

Question 17. Enumerate the types of syngamy.

Answer:

1. Autogamy
2. Exogamy
3. Hologamy
4. Paedogamy
5. Merogamy
6. Isogamy
7. Anisogamy
8. Conjugation

Question 18. Name the types of animals based on embryonic development with an example for each.

Answer:

• Oviparous animals

e.g. Birds

• Viviparous animals

e.g. Human beings

• Ovoviviparous animals

e.g. Shark

Question 19. What is autogamy?

Answer: In autogamy, the male and female gametes are produced by the same cell or same organism and both the gametes fuse together to form a zygote.
e.g. Actinosphaerium and Paramecium.

Question 20. What is exogamy?

Answer: In exogamy, the male and female gametes are produced by different parents and they fuse to form a zygote. So it is biparental. e.g. Human – dioecious or unisexual animal.

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