April 10, 2026
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Chapter 8: How do Organisms Reproduce?
Complete NCERT Solutions (Intext + Exercise) | CBSE Class 10 Science |Questions & Marks
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Intext Questions (Page 128)
12 marks
What is the importance of DNA copying in reproduction?
Answer: DNA copying ensures transmission of genetic information from parent to offspring. It also introduces minor variations, which are essential for evolution and adaptation.
22 marks
Why is variation beneficial to the species but not necessarily for the individual?
Answer: Variations help a species survive in changing environments (natural selection). For an individual, a variation may be harmful or neutral, but for the species, it increases adaptability.
Intext Questions (Page 133)
32 marks
How does binary fission differ from multiple fission?
Answer: Binary fission produces two daughter cells (e.g., Amoeba, bacteria). Multiple fission produces many daughter cells simultaneously (e.g., Plasmodium).
42 marks
How will an organism be benefited if it reproduces through spores?
Answer: Spores are tiny, lightweight, and can be dispersed by wind/water. They remain dormant under unfavorable conditions and germinate when conditions improve, ensuring survival.
52 marks
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer: Complex organisms have highly specialized tissues and organs. Regeneration requires a simple body plan and ability to dedifferentiate cells, which complex organisms lack.
62 marks
Why is vegetative propagation practised for growing some types of plants?
Answer: Vegetative propagation produces genetically identical plants (clones) faster. It preserves desirable traits and can propagate seedless plants (e.g., banana, rose).
72 marks
Why is DNA copying an essential part of the process of reproduction?
Answer: DNA copying transfers genetic information to offspring, ensuring continuity of species. It also allows variations, which are raw material for evolution.
Intext Questions (Page 140)
83 marks
How is the process of pollination different from fertilisation?
Answer: Pollination is transfer of pollen grains from anther to stigma. Fertilisation is fusion of male gamete (from pollen tube) with female gamete (ovule) to form zygote.
93 marks
What is the role of the seminal vesicles and the prostate gland?
Answer: Both secrete fluids that form semen. Seminal vesicles produce a fructose-rich fluid that nourishes sperm. Prostate gland secretes an alkaline fluid that neutralizes vaginal acidity, enhancing sperm motility.
103 marks
What are the changes seen in girls at the time of puberty?
Answer: Breast development, menstruation, growth of pubic/armpit hair, widening of hips, voice change (slight), and increased oil secretion (acne).
113 marks
How does the embryo get nourishment inside the mother's body?
Answer: The embryo gets nourishment through the placenta. Placenta contains villi that increase surface area for exchange of nutrients, oxygen, and waste between mother and foetus.
122 marks
If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Answer: No. Copper-T prevents pregnancy but does not protect against STDs. Only condoms provide protection against STDs.
NCERT Exercise Questions (Page 140)
Ex 11 mark
Asexual reproduction takes place through budding in (a) Amoeba (b) Yeast (c) Plasmodium (d) Leishmania.
Answer: (b) Yeast.
Ex 22 marks
Which 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: (c) Vas deferens – it is part of the male reproductive system.
Ex 32 marks
The anther contains (a) sepals (b) ovules (c) pistil (d) pollen grains.
Answer: (d) pollen grains.
Ex 43 marks
What are the advantages of sexual reproduction over asexual reproduction?
Answer: Sexual reproduction generates genetic diversity, which helps species adapt to changing environments. It eliminates harmful mutations and combines beneficial traits.
Ex 53 marks
What are the functions performed by the testis in human beings?
Answer: Testes produce male gametes (sperm) and secrete the male hormone testosterone, which regulates sperm production and secondary sexual characteristics.
Ex 63 marks
Why does menstruation occur?
Answer: Menstruation occurs when the released egg is not fertilised. The thickened uterine lining (endometrium) breaks down and is shed along with blood and mucus.
Ex 73 marks
Draw a labelled diagram of the longitudinal section of a flower.
Answer: A flower has sepals, petals, stamens (anther + filament), and pistil (stigma, style, ovary containing ovules).
Ex 83 marks
What are the different methods of contraception?
Answer: Barrier methods (condoms, diaphragms), hormonal methods (pills, implants), intrauterine devices (Copper-T), surgical methods (vasectomy, tubectomy), and natural methods (withdrawal, rhythm).
Ex 93 marks
How are the modes of reproduction different in unicellular and multicellular organisms?
Answer: Unicellular organisms reproduce mainly by binary fission, multiple fission, or budding. Multicellular organisms can reproduce asexually (vegetative propagation, fragmentation) or sexually (fusion of gametes).
Ex 103 marks
How does reproduction help in providing stability to populations of species?
Answer: Reproduction replaces dying individuals, maintaining population size. Genetic variations from sexual reproduction help species adapt to environmental changes, ensuring long-term survival.
Ex 113 marks
What could be the reasons for adopting contraceptive methods?
Answer: To prevent unwanted pregnancies, to space children, to control population growth, and to reduce the risk of sexually transmitted diseases (condoms).
Additional Important Questions
A12 marks
What is the role of the fallopian tube in the female reproductive system?
Answer: The fallopian tube carries the egg from the ovary to the uterus. Fertilisation occurs here if sperm are present.
A22 marks
Name the techniques used in vegetative propagation.
Answer: Cutting, layering, grafting, and tissue culture.
A32 marks
Define (a) puberty (b) menopause.
Answer: (a) Puberty: the stage when reproductive maturity is reached. (b) Menopause: the permanent cessation of menstruation and fertility in women (around age 45-50).
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