Plus Two Botany Class Notes First Bell 2.0

CHAPTER 1 Part-02


Important Questions and Answers  Part -02

11. What is vegetative propagation?

In plants, the units of vegetative propagation such as runner, rhizome, sucker, tuber, offset, bulb are all capable of giving rise to new offspring. These structures are called vegetative propagules.

12. What is sexual reproduction ?

Sexual reproduction involves formation of the male and female gametes either by the same individual or by different individuals of the opposite sex. These gametes fuse to form the zygote which develops to form the new organism. 

13. What are events involved in sexual reproduction?

pre-fertilisation, fertilisation and the post-fertilisation events.

14. Explain pre- fertilization events

The two main pre-fertilisation events are gametogenesis and gamete transfer. gametogenesis refers to the process of formation of the two types of gametes – male and female. Gametes are haploid cells. After their formation, male and female gametes must be physically brought together to facilitate fusion (fertilisation).

15. What is  fertilization ?

 The most vital event of sexual reproduction is perhaps the fusion of gametes. This process called syngamy  results in the formation of a diploid zygote. 

16. What are two types of fertilization?

These are external and internal fertilization. syngamy occurs in the external medium (water), i.e., outside the body of the organism. This type of gametic fusion is called external fertilisation. , syngamy occurs inside the body of the organism, hence the process is called internal fertilisation.

17. Explain post fertilization events?

Events in sexual reproduction after the formation of zygote are called post-fertilisation events. These include zygote, embryogenisis.  The Zygote Formation of the diploid zygote is universal in all sexually reproducing organisms. In organisms with external fertilisation, zygote is formed in the external medium (usually water), whereas in those exhibiting internal fertilisation, zygote is formed inside the body of the organism. Embryogenesis refers to the process of development of embryo from the zygote. During embryogenesis, zygote undergoes cell division (mitosis) and cell differentiation. While cell divisions increase the number of cells in the developing embryo; cell differentiation helps groups of cells to undergo certain modifications to form specialised tissues and organs to form an organism.

18. What is parthenogenesis?

The female gamete undergoes development to form new organisms without fertilisation. This phenomenon is called parthenogenesis.

19. Explain  fruit development in plants?

In flowering plants, the zygote is formed inside the ovule. After fertilisation the sepals, petals and stamens of the flower wither and fall off. The pistil however, remains attached to the plant. The zygote develops into the embryo and the ovules develop into the seed. The ovary develops into the fruit which develops a thick wall called pericarp that is protective in function.

20. Find chromosome number of following

Human being, butterfly and dog

1. Human being – 46

2. Butterfly    - 380

3. Dog -  78

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