Class 10 Science · Chapter 7

How do Organisms Reproduce?

434 Class 10 Science questions on How do Organisms Reproduce? from the NCERT textbook, NCERT Exemplar and CBSE board papers 2017–2026, each with its answer and a step-by-step solution.

NCERT exercises

Exercises (11) Intext Questions (Page 114) (2) Intext Questions (Page 119) (5) Intext Questions (Page 126) (5)

NCERT Exemplar exercises

Multiple Choice Questions (27) Short Answer Questions (21) Long Answer Questions (10)

CBSE Class 10 Science previous year papers, with answers →

Questions · page 7 of 22

Q121 CBSE 2026
Radha has three children. She does not want to have more children. Radha visits a nearby hospital, to know the methods to prevent pregnancy.
1. (i)Mention the name of any two ways other than the surgical methods, following which Radha can avoid unwanted pregnancies.
2. (ii)Name the surgical methods to prevent pregnancy.
3. (iii)Give one example each of sexually transmitted diseases caused by bacteria and virus.
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Radha can use oral pills or condoms; the surgical methods are vasectomy and tubectomy; gonorrhoea is a bacterial and HIV-AIDS a viral STD.
(i) Any two of: oral contraceptive pills, which change the hormonal balance so that eggs are not released; a copper-T (or loop) placed in the uterus; barrier methods such as a condom on the penis or a similar covering worn in the vagina, which stop the sperms from reaching the egg. (ii) Vasectomy, in which the vas deferens of the male is blocked so that sperms are not transferred; and tubectomy, in which the fallopian tubes of the female are blocked so that the egg cannot reach the uterus. (iii) Caused by bacteria: gonorrhoea (or syphilis); caused by a virus: HIV-AIDS (or warts).

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Q122 CBSE 2026
Observe the given diagram and answer the questions that follow :
1. (i)Give the name and type of reproduction shown in the above diagram.
2. (ii)Comment on the processes taking place in stage P.
3. (iii)Name an organism which reproduces by the above mentioned method.
4. (iv)Name the method that can be used to raise plants that have lost their capacity to produce seeds. List any two advantages of growing plants by such a method.
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Multiple fission (asexual) occurs in Plasmodium; vegetative propagation raises plants that cannot make seeds, giving earlier flowering and genetically similar plants.
(i) The diagram shows multiple fission, a type of asexual reproduction. (ii) In stage P, inside the protective cyst, the nucleus divides repeatedly to form many nuclei; the cytoplasm then divides so that a small part of it surrounds each nucleus, forming many small daughter cells within the cyst. When conditions become favourable the cyst breaks and the daughter cells are released. (iii) Plasmodium (the malarial parasite). (iv) Vegetative propagation, for example by layering, grafting or cuttings (as for banana, orange, rose and jasmine). Advantages: the plants bear flowers and fruits earlier than plants grown from seeds; all the plants are genetically similar to the parent, so its desirable characters are kept.

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Q123 CBSE 2026
1. (i)Sugarcane does not produce seeds so name the process through which it will be able to reproduce.
2. (ii)List any two advantages of this method.
3. (iii)Besides sugarcane, give two more examples of plants that reproduce by this method.
4. (iv)Why regeneration is not possible in all the types of animals ?
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Sugarcane reproduces by vegetative propagation, which keeps the parent's characters; complex animals cannot regenerate because their specialised cells cannot rebuild the whole body.
(i) Vegetative propagation. Pieces of the sugarcane stem bearing nodes with buds are planted, and each bud grows into a new plant. (ii) Any two: the new plants are genetically similar to the parent, so the characteristics of a good variety are retained; they bear flowers and fruits earlier than plants grown from seeds; and the method allows plants that have lost the capacity to produce seeds (banana, orange, rose, jasmine) to be propagated. (iii) Rose and grapes (banana, jasmine, potato or Bryophyllum are equally acceptable). (iv) Regeneration is carried out by specialised cells that multiply and then change, in an organised sequence, into all the different cell types and tissues; only organisms that have such cells can regenerate. Simple animals such as Hydra and Planaria have them, so a cut piece can grow into a complete organism. Complex animals do not: their body cells have already become particular kinds of cells, organised into tissues, organs and organ systems that must lie at definite positions in the body, so a fragment cannot rebuild the entire organised body, and a whole individual cannot be regenerated.

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Q124 CBSE 2026
1. (i)Name the special tissue inside the uterus that provides nutrition to the developing embryo. Describe its structure. State its two functions besides nutrition.
2. (ii)Write any two sexually transmitted diseases in humans and their causative microbial agents.
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The placenta nourishes the embryo, exchanges gases and removes wastes; gonorrhoea (bacterium) and AIDS (virus) are two sexually transmitted diseases.
(i) The tissue is the placenta. It is a disc-shaped tissue embedded in the wall of the uterus; villi grow out from the embryo's side of the disc into blood spaces (sinuses) filled with the mother's blood, which gives a very large surface for exchange, and the embryo is joined to the disc by the umbilical cord. Two functions besides nutrition: it passes oxygen from the mother's blood to the embryo and carries carbon dioxide back; and it removes the embryo's nitrogenous wastes, chiefly urea, into the mother's blood. (The placenta also secretes hormones that help to maintain the pregnancy.) (ii) Gonorrhoea is caused by the bacterium Neisseria gonorrhoeae, and AIDS is caused by a virus, the Human Immunodeficiency Virus (HIV). Syphilis (bacterium Treponema pallidum) and warts (human papilloma virus) are equally acceptable pairs.

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Q125 CBSE 2026
1. (i)Differentiate between self-pollination and cross-pollination. (two points)
2. (ii)Explain how does pollination lead to fertilisation in flowering plants.
3. (iii)Name the end-products of sexual reproduction in plants.
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Self-pollination is within the same flower, cross-pollination between flowers; the pollen tube enables fertilisation, and the end-products are the seed and fruit.
(i) In self-pollination the pollen is transferred from the anther to the stigma of the **same** flower, whereas in cross-pollination it is transferred from one flower to **another** flower. Self-pollination may or may not need a pollinating agent, whereas cross-pollination always needs an agent — wind, water or an animal such as an insect or bird. (ii) Pollination only places the pollen grain on the stigma. There the grain germinates and puts out a pollen tube, which grows down through the style, reaches the ovary and enters an ovule, carrying the male germ cell with it. Inside the ovule that male gamete fuses with the female gamete (the egg), and this fusion is fertilisation; it produces the zygote. So pollination leads to fertilisation through the growth of the pollen tube, and the two events are not the same. (iii) The zygote grows into the **embryo**, the ovule becomes the **seed** and the ovary becomes the **fruit**. The end-products of sexual reproduction in plants are therefore the seed, containing the embryo, and the fruit.

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Q126 CBSE 2026

What are sexually transmitted diseases ? Name any one sexually transmitted disease caused by virus and a bacterium. List any two contraceptive methods with their advantages.

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STDs spread through sexual contact; HIV-AIDS is viral and gonorrhoea bacterial; the condom and oral pills are two contraceptive methods with advantages.
Sexually transmitted diseases are diseases that spread from an infected person to a healthy person through sexual contact. Caused by a virus: HIV-AIDS (or warts). Caused by a bacterium: gonorrhoea (or syphilis). Two contraceptive methods with their advantages: (1) Condom, a mechanical barrier - it stops the sperm from reaching the egg; it also helps to prevent the spread of STDs between partners and has no hormonal side-effects. (2) Oral contraceptive pills - they change the hormonal balance so that no egg is released; they are highly effective when taken regularly, need no device or surgery, and can be stopped whenever a child is wanted. Also acceptable: a copper-T or loop in the uterus, which protects for several years and can be removed; or surgery - vasectomy or tubectomy - which is permanent.

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Q127 CBSE 2025

Match Column-I with Column-II and select the correct option from the choices provided.

Column-I and Column-II
Column-I	Column-II
a. Site of fertilisation of egg with the sperm	(i) Vagina
b. Site of implantation of embryo	(ii) Uterus
c. Site of entry of sperm into the female reproductive tract	(iii) Oviduct
d. Site through which the waste materials generated by the developing embryo are removed	(iv) Placenta
	(v) Cervix

(a)a-(ii), b-(i), c-(v), d-(iv)
(b)a-(iii), b-(i), c-(v), d-(iv)
(c)a-(iv), b-(ii), c-(iii), d-(i)
(d)a-(iii), b-(ii), c-(i), d-(iv)

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(d) a-(iii), b-(ii), c-(i), d-(iv)

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Q128 CBSE 2025
Plants like rose and banana have lost the capacity to produce :
1. (a)flowers
2. (b)buds
3. (c)seeds
4. (d)fruits
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(c) seeds

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Q129 CBSE 2025
In a bisexual flower the male gametes are present in the :
1. (a)anther
2. (b)ovary
3. (c)stigma
4. (d)filament
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(a) anther

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Q130 CBSE 2025
Which one of the following has half the number of chromosomes and half the amount of DNA as compared to the non-reproductive body cells?
1. (a)Male germ cell
2. (b)Female germ cell
3. (c)Zygote
4. (d)Both, male and female germ cells
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(d) Both, male and female germ cells

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Q131 CBSE 2025
Bryophyllum produces new plant through :
1. (a)Apical buds formed on the tip of the plant
2. (b)Vegetative buds produced in the notches of the leaf
3. (c)Flowers produced in the notches of the branches
4. (d)Fruits formed on the branches of the plant
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(b) Vegetative buds produced in the notches of the leaf

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Q132 CBSE 2025
Select a pair of bisexual flowers from the following :
1. (a)Papaya and mustard
2. (b)Hibiscus and mustard
3. (c)Hibiscus and papaya
4. (d)Hibiscus and watermelon
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(b) Hibiscus and mustard

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Q133 CBSE 2025
The end product of meiosis in a reproductive cell in plants is :
1. (a)Zygote
2. (b)Pollen grains
3. (c)Sperms
4. (d)Egg
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(b) Pollen grains

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Q134 CBSE 2025
Which one of the following statements is not correct for the plants raised by vegetative propagation ?
1. (a)Can bear flowers and fruits earlier than those produced from seeds.
2. (b)Those plants that have lost the capacity to produce seeds can be grown.
3. (c)As compared to the parent plant, vegetatively propagated plants show more variations.
4. (d)All the plants produced in this way are genetically similar to the parent plant.
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(c) As compared to the parent plant, vegetatively propagated plants show more variations.

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Q135 CBSE 2025
Which of the following is the correct sequence of parts of female reproductive system of flowering plants in terms of their placement ?
1. (a)Stigma, ovule, ovary, style
2. (b)Ovule, stigma, ovary, style
3. (c)Style, stigma, ovule, ovary
4. (d)Stigma, style, ovary, ovule
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(d) Stigma, style, ovary, ovule

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Q136 CBSE 2025
The correct/true statement(s) for a bisexual flower is/are :
1. (i)They possess both stamen and pistil.
2. (ii)They possess either stamen or pistil.
3. (iii)They exhibit either self-pollination or cross-pollination.
4. (iv)They cannot produce fruits on their own.
1. (a)(i) only
2. (b)(iv) only
3. (c)(i) and (iii)
4. (d)(i) and (iv)
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(c) (i) and (iii)

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Q137 CBSE 2025
The number of chromosomes in a cell division is halved. This kind of cell division is observed in :
1. (a)Only testis
2. (b)Only ovary
3. (c)Ovary and testis both
4. (d)All cells of the body
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(c) Ovary and testis both

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Q138 CBSE 2025
The modes of reproduction in Spirogyra and Planaria respectively are
1. (a)Regeneration and budding
2. (b)Regeneration and fragmentation
3. (c)Fragmentation and regeneration
4. (d)Budding and regeneration
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(c) Fragmentation and regeneration

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Q139 CBSE 2025
Select the option having correct matching of the organism given in Column I with the mode of reproduction in Column II :
1. (a)P-4, Q-2, R-1, S-3
2. (b)P-3, Q-4, R-5, S-2
3. (c)P-3, Q-4, R-1, S-2
4. (d)P-4, Q-3, R-2, S-1
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(c) P-3, Q-4, R-1, S-2

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Q140 CBSE 2025
When a seed germinates the root grows downwards and a small shoot grows upward. This shoot is known as
1. (a)radicle
2. (b)stem
3. (c)cotyledon
4. (d)plumule
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(d) plumule

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