Chapter 7: How do Organisms Reproduce? Exercise & In-Text Questions & Answers
1What is the importance of DNA copying in reproduction?
Answer & Reference:
DNA copying is essential because it carries the blueprint for body design. It ensures that offspring inherit features from parents. The copied DNA, along with cellular apparatus, forms new cells. (Reprint 2025–26, p. 114, para 7.1)
2Why is variation beneficial to the species but not necessarily for the individual?
Answer & Reference:
Variation helps species survive environmental changes (e.g., temperature rise). While an individual may not benefit (and may even die), a few variants in the population may survive, ensuring species continuity. (p. 115, para 7.1.1)
3How does binary fission differ from multiple fission?
Answer & Reference:
In binary fission, one cell divides into two equal daughter cells (e.g., Amoeba). In multiple fission, one cell divides into many daughter cells simultaneously (e.g., Plasmodium). (p. 116, Fig. 7.1 & 7.2)
4How will an organism be benefited if it reproduces through spores?
Answer & Reference:
Spores are covered by thick walls that protect them in unfavourable conditions. They can remain dormant until they land on a moist surface and grow into new individuals. (p. 118, para 7.2.6)
5Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer & Reference:
Complex organisms have specialised tissues and organs arranged in a definite pattern. Cell-by-cell division or regeneration from fragments is impractical due to this high level of organisation. (p. 116, para after Activity 7.4)
6Why is vegetative propagation practised for growing some types of plants?
Answer & Reference:
It is used for plants that have lost seed-producing capacity (e.g., banana, rose). It allows early flowering/fruiting and produces genetically identical plants with desired traits. (p. 117–118, para 7.2.5)
7Why is DNA copying an essential part of the process of reproduction?
Answer & Reference:
DNA copying ensures inheritance of traits. Without it, new individuals would not resemble parents, and species characteristics could not be maintained. (p. 114, para 7.1)
8How is the process of pollination different from fertilisation?
Answer & Reference: Pollination is the transfer of pollen from anther to stigma (may be self or cross). Fertilisation is the fusion of male and female gametes to form a zygote. (p. 121, para 7.3.2)
9What is the role of the seminal vesicles and the prostate gland?
Answer & Reference:
These glands add secretions to sperms, forming semen. This fluid makes sperm transport easier and provides nutrition. (p. 123, para 7.3.3a)
10What are the changes seen in girls at the time of puberty?
Answer & Reference:
Breast size increases, nipples darken, menstruation begins, and hair grows in armpits and genital area. Skin may become oily with pimples. (p. 122, para 7.3.3)
11How does the embryo get nourishment inside the mother’s body?
Answer & Reference:
Through the placenta—a special tissue with villi on the embryo side and blood spaces on the mother’s side—allowing exchange of glucose, oxygen, and waste. (p. 124, para 7.3.3b)
12If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Answer & Reference:
No. Copper-T prevents pregnancy by blocking implantation but does not protect against sexually transmitted diseases (STDs). Only condoms offer some protection. (p. 125, para 7.3.3d)
13Asexual reproduction takes place through budding in (a) Amoeba (b) Yeast (c) Plasmodium (d) Leishmania
Answer & Reference: (b) Yeast. Yeast reproduces by forming buds that detach and grow. (p. 116, para 7.2.1)
14Which of the following is not a part of the female reproductive system in human beings? (a) Ovary (b) Uterus (c) Vas deferens (d) Fallopian tube
Answer & Reference: (c) Vas deferens — it is part of the male reproductive system. (p. 123–124, Fig. 7.10 & 7.11)
Answer & Reference: (d) pollen grains. The stamen (which includes anther) produces pollen grains. (p. 121, para 7.3.2)
16What are the advantages of sexual reproduction over asexual reproduction?
Answer & Reference:
Sexual reproduction creates more variations by combining DNA from two individuals. This increases chances of species survival in changing environments. Asexual reproduction produces less variation. (p. 120, para 7.3.1)
17What are the functions performed by the testis in human beings?
Answer & Reference:
Testes produce sperms and secrete the hormone testosterone, which regulates sperm production and causes puberty changes in boys. (p. 123, para 7.3.3a)
18Why does menstruation occur?
Answer & Reference:
If the egg is not fertilised, the thickened uterine lining is no longer needed and breaks down, coming out as blood and mucus through the vagina. This monthly cycle is called menstruation. (p. 124, para 7.3.3c)
19Draw a labelled diagram of the longitudinal section of a flower.
Answer & Reference:
See simplified SVG below based on Fig. 7.7 (p. 121).
20What are the different methods of contraception?
21How are the modes for reproduction different in unicellular and multicellular organisms?
Answer & Reference: Unicellular organisms reproduce by fission, budding, etc. (simple cell division). Multicellular organisms use specialised reproductive cells (e.g., spores, gametes) or vegetative parts due to complex body organisation. (p. 116, para after Activity 7.4)
22How does reproduction help in providing stability to populations of species?
Answer & Reference:
Reproduction maintains consistent body design through accurate DNA copying, allowing species to occupy their ecological niche. Variations ensure survival if the niche changes. (p. 115, para 7.1.1)
23What could be the reasons for adopting contraceptive methods?
Answer & Reference:
To avoid unwanted pregnancies, maintain health of women, control population growth, and prevent sexually transmitted diseases (when using condoms). (p. 125, para 7.3.3d)
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