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 15 of 22

Q281 CBSE 2022

What is vegetative propagation ? Name two methods in which this process is used to grow many plants. List any two advantages of vegetative propagation.

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Vegetative propagation raises plants from parent parts without seeds, by layering or grafting, with earlier fruiting and propagation of seedless plants as advantages.
Vegetative propagation is a mode of asexual reproduction in which new plants develop from vegetative parts of a parent plant (the root, the stem or the leaves) under appropriate conditions, without seeds. Two methods: layering and grafting. (Growing plants from stem cuttings is another.) Advantages (any two): (1) the plants bear flowers and fruits earlier than plants raised from seeds; (2) plants that have lost the capacity to produce seeds, such as banana, orange, rose and jasmine, can be propagated; (3) the new plants are genetically similar enough to the parent plant to have all its characteristics, so a desired variety is preserved.

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Q282 CBSE 2022
Write the functions of the following parts of the human female reproductive system :
1. (i)Ovary
2. (ii)Fallopian tube
3. (iii)Uterus
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The ovary makes eggs, the fallopian tube carries the egg and is the site of fertilisation, and the foetus develops in the uterus.
(i) Ovary: produces the female gametes, the eggs (ova); from puberty one egg is produced every month by one of the ovaries. The ovaries also secrete the female sex hormones, such as oestrogen. (ii) Fallopian tube (oviduct): carries the egg from the ovary towards the uterus, and is the site of fertilisation, where a sperm fuses with the egg. (iii) Uterus: the fertilised egg (zygote) is implanted in its thick, blood-rich lining and develops there into the embryo and foetus, which is nourished from the mother's blood through the placenta; at birth, rhythmic contractions of its muscles push the baby out.

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Q283 CBSE 2022
(a) Explain the surgical method of contraception used by
1. (i)males, and
2. (ii)females to prevent fertilisation. (b) Write the role of oral pills taken by women as a contraceptive.
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Vasectomy cuts and ties the vas deferens, tubectomy the fallopian tubes, and oral pills stop the release of eggs.
(a) (i) Males: In the surgical method (vasectomy), a small portion of each vas deferens (sperm duct) is cut and the cut ends are tied. Sperms from the testes can then no longer pass along the ducts, so no sperms are transferred and fertilisation is prevented. (ii) Females: In the surgical method (tubectomy), a small portion of each fallopian tube (oviduct) is cut and the cut ends are tied. The egg released from the ovary can no longer reach the uterus, and sperms cannot reach the egg, so fertilisation is prevented. (b) Oral pills contain hormones that change the hormonal balance of the body so that eggs are not released from the ovaries. With no egg released, fertilisation cannot take place, so pregnancy is prevented. Because they change the hormonal balance, the pills can also have side-effects.

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Q284 CBSE 2022

Differentiate between binary fission and multiple fission giving one example for each.

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Binary fission gives two cells by one division (Amoeba); multiple fission gives many cells released together (Plasmodium).
Binary fission and multiple fission differ as follows: (i) In binary fission the parent cell divides into two daughter cells; in multiple fission it divides into many daughter cells. (ii) In binary fission the nucleus divides once and the cytoplasm then splits into two; in multiple fission the nucleus divides repeatedly to form many nuclei, and a little cytoplasm gathers round each of them. (iii) In binary fission one division gives two cells; in multiple fission many daughter cells are formed and released together, at the same time. Examples: binary fission, Amoeba; multiple fission, Plasmodium (the malarial parasite).

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Q285 CBSE 2022
We are all aware of the term reproduction and we know that the continuity of life on our Earth from the origin to the present day has been possible only because of reproduction. Sexual reproduction is the most common mode of reproduction in flowering plants (angiosperms). Seeds are produced as a result of sexual reproduction. New plants are produced from these seeds only. In angiosperms, flower is the reproductive part of a plant. Most flowers have both male and female reproductive organs in them.
1. (a)Name the (i) male, and (ii) female part of a flowering plant.[1]
2. (b)What happens to the zygote after fertilisation ?[1]
3. (c)(i)Differentiate between self-pollination and cross-pollination.[2]
4. (c)(ii)OR : Explain in brief, how fertilisation takes place in angiosperms.[2]
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Stamen is male and pistil female; the zygote divides into an embryo, the ovule becomes a seed and the ovary a fruit.
(a) (i) The male part is the stamen (anther and filament; the anther makes the pollen grains). (ii) The female part is the pistil, or carpel (stigma, style and ovary; the ovary contains the ovules). (b) After fertilisation the zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and becomes a seed, and the ovary ripens into a fruit. (c)(i) Self-pollination is the transfer of pollen from the anther to the stigma of the same flower; it can take place without an outside agent and produces less variation. Cross-pollination is the transfer of pollen from one flower to the stigma of another flower, usually on another plant of the same species; it needs an agent such as wind, water, insects or birds, and, when the pollen comes from another plant, produces more variation. OR (c)(ii) The pollen grain that has landed on the stigma grows a pollen tube, which travels down through the style into the ovary and enters an ovule. The male germ cell carried by the tube fuses there with the female germ cell (egg); this fusion is fertilisation, and it forms the zygote.

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Q286 CBSE 2022
The modes by which various organisms reproduce depend on the body design of the organisms. In asexual reproduction, a single individual parent produces offsprings without the involvement of gametes. This method is a common means of increasing the offsprings rapidly under favourable conditions. Asexual reproduction occurs mostly in unicellular organisms, some plants and certain simple multicellular animals.
1. (a)Why is regeneration not same as reproduction ?[1]
2. (b)List any two advantages of producing plants through vegetative propagation.[1]
3. (c)(i)Explain the process of budding in Hydra.[2]
4. (c)(ii)OR : What happens when (I) a spirogyra filament matures and attains a considerable length, and (II) a sporangia in Rhizopus bursts on maturation ?[2]
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(a) Regeneration is the ability of a fully differentiated organism to give rise to new individuals from its body parts when it is cut or broken up, as in Planaria and Hydra. It is not the same as reproduction because it happens only after the body is cut up, and most organisms do not normally depend on being cut up in order to reproduce; reproduction is the normal way in which organisms produce new individuals. (b) Any two: plants raised by vegetative propagation bear flowers and fruits earlier than those raised from seeds; plants that have lost the capacity to produce seeds, such as banana, orange, rose and jasmine, can be propagated; all the plants produced are genetically similar enough to the parent to have all its characteristics. (c)(i) In Hydra a bud develops as an outgrowth due to repeated cell division at one specific site on the body. The bud grows, develops tentacles and a mouth, and becomes a tiny individual. When fully mature it detaches from the parent and becomes a new independent Hydra. OR (c)(ii) (I) The mature Spirogyra filament simply breaks up into two or more small pieces (fragments), and each fragment grows into a new individual; this is fragmentation. (II) The spores inside the sporangium are set free; protected by their thick walls, they are dispersed, and each spore that reaches a moist surface grows into a new Rhizopus individual; this is spore formation.

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Q287 CBSE 2022
The modes by which various organisms reproduce depend on the body design of the organisms. In asexual reproduction, a single individual parent produces offsprings without the involvement of gametes. This method is a common means of increasing the offsprings rapidly under favourable conditions. Asexual reproduction occurs mostly in unicellular organisms, some plants and certain simple multicellular animals.
1. (a)State the name of the organism in which binary fission takes place in a definite orientation. Also name the disease caused by this organism.[1]
2. (b)List any two advantages of producing plants through vegetative propagation.[1]
3. (c)(i)Explain the process of budding in Hydra.[2]
4. (c)(ii)OR : What happens when (I) a spirogyra filament matures and attains a considerable length, and (II) a sporangia in Rhizopus bursts on maturation ?[2]
Show answer

Leishmania causes kala-azar; vegetative propagation gives earlier flowering; Hydra reproduces by budding; Spirogyra fragments and Rhizopus sporangia release spores.
(a) Leishmania, which divides by binary fission in a definite orientation in relation to the whip-like structure (flagellum) at one end of its cell. It causes kala-azar. (b) Any two: plants raised by vegetative propagation bear flowers and fruits earlier than those produced from seeds; plants that have lost the capacity to produce seeds, such as banana, orange, rose and jasmine, can still be propagated; the new plants are genetically similar enough to the parent plant to have all its characteristics. (c)(i) Hydra reproduces by budding, using its regenerative cells. At one specific site on the body, repeated cell division produces an outgrowth called a bud. The bud develops into a tiny individual with its own mouth and tentacles, and when fully mature it detaches from the parent body and becomes a new, independent individual. OR (c)(ii) (I) The mature Spirogyra filament simply breaks up into smaller pieces (fragments), and each fragment grows into a new individual; this is fragmentation. (II) The bursting sporangium releases a large number of spores; protected by their thick walls, the spores grow into new Rhizopus individuals when they come in contact with a moist surface.

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Q288 CBSE 2022
The modes by which various organisms reproduce depend on the body design of the organisms. In asexual reproduction, a single individual parent produces offsprings without the involvement of gametes. This method is a common means of increasing the offsprings rapidly under favourable conditions. Asexual reproduction occurs mostly in unicellular organisms, some plants and certain simple multicellular animals.
1. (a)State the name of the organism in which binary fission takes place in a definite orientation. Also name the disease caused by this organism.[1]
2. (b)Leaves of ‘Bryophyllum’ when they fall on the soil develop into new plants whereas a banana leaf will not be able to do so. Why ?[1]
3. (c)(i)Explain the process of budding in Hydra.[2]
4. (c)(ii)OR : What happens when (I) a spirogyra filament matures and attains a considerable length, and (II) a sporangia in Rhizopus bursts on maturation ?[2]
Show answer

(a) Leishmania; it causes kala-azar. (b) Bryophyllum produces buds in the notches along the margin of its leaves, and when a leaf falls on the soil these buds develop into new plants (vegetative propagation). A banana leaf bears no such buds, so it cannot give rise to new plants. (c)(i) Budding in Hydra: a bud develops as an outgrowth due to repeated cell division at one specific site on the body. The bud grows into a tiny individual with its own tentacles while still attached to the parent, and when fully mature it detaches from the parent body and becomes a new, independent Hydra. OR (c)(ii) (I) The mature Spirogyra filament simply breaks up into smaller pieces, or fragments, and each fragment grows into a new individual (fragmentation). (II) When a mature sporangium of Rhizopus bursts, the spores inside it are released; protected by thick walls, they grow into new Rhizopus individuals when they come into contact with a moist surface (spore formation).

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Q289 CBSE 2020

Name two infections which can be sexually transmitted in human beings.

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Any two of gonorrhoea, syphilis, warts and HIV-AIDS, for example gonorrhoea and HIV-AIDS.
Any two of: gonorrhoea, syphilis (both caused by bacteria), warts and HIV-AIDS (both caused by viruses). For example, gonorrhoea and HIV-AIDS.

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Q290 CBSE 2020
Answer question numbers 3(a) to 3(d) and 4(a) to 4(d) on the basis of your understanding of the following paragraphs and the related studied concepts. The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not necessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of population.
1. (a)List two common signs of sexual maturation in boys and girls.[1]
2. (b)What is the result of reckless female foeticide ?[1]
3. (c)Which contraceptive method changes the hormonal balance of the body ?[1]
4. (d)Write two factors that determine the size of a population.[1]
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Signs: body hair and oily skin; foeticide lowers the child sex ratio; oral pills change hormones; birth and death rates fix population size.
(a) Any two of: thick hair growth in the armpits and the genital area; thinner hair on the arms, legs and face; oily skin because the oil glands become more active; pimples. (b) The child sex ratio falls: fewer girls are born than boys, so the male–female ratio of the population becomes imbalanced. (c) Oral contraceptive pills, the hormonal method. (d) The birth rate and the death rate.

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Q291 CBSE 2020
Fertilisation is the process of
1. (a)transfer of male gamete to female gamete.
2. (b)fusion of nuclei of male and female gamete.
3. (c)adhesion of male and female reproductive organs.
4. (d)the formation of gametes by a reproductive organ.
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(b) fusion of nuclei of male and female gamete.

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Q292 CBSE 2020
Which of the following statements is not true about a ‘bud’ in ‘Hydra’ ?
1. (a)It is an outgrowth.
2. (b)It forms due to repeated cell division at one specific site.
3. (c)It detaches from the parent body as soon as it is produced.
4. (d)It becomes a new independent individual.
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(c) It detaches from the parent body as soon as it is produced.

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Q293 CBSE 2020
The stamen contains
1. (a)stigma
2. (b)pollen grain
3. (c)sepal
4. (d)ovule
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(b) pollen grain

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Q294 CBSE 2020
Which one of the following is not a part of the human female reproductive system ?
1. (a)Ovary
2. (b)Oviduct
3. (c)Uterus
4. (d)Seminal vesicle
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(d) Seminal vesicle

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Q295 CBSE 2020
Seeds are called products of sexual reproduction because they
1. (a)give rise to new plants.
2. (b)are formed by fusion of gametes.
3. (c)are formed by the fusion of pollen tubes.
4. (d)can survive for a longer period.
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(b) are formed by fusion of gametes.

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Q296 CBSE 2020
Which of the following techniques is used as a contraceptive method in males only ?
1. (a)Copper-T
2. (b)Oral pills
3. (c)Blockage of fallopian tube
4. (d)Blockage of vas deferens
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(d) Blockage of vas deferens

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Q297 CBSE 2020
For question numbers 13 and 14, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :
Assertion (A): Amoeba always produces two daughter amoebae while Plasmodium divides into many daughter cells.
Reason (R): Amoeba undergoes binary fission while Plasmodium undergoes multiple fission.
1. (a)Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).
2. (b)Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).
3. (c)(A) is true, but (R) is false.
4. (d)(A) is false, but (R) is true.
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(a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

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Q298 CBSE 2020
For question numbers 13 and 14, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :
Assertion (A): Testes are located outside the abdominal cavity in the scrotum.
Reason (R): Because sperm formation requires lower temperature than the normal body temperature.
1. (a)Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).
2. (b)Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).
3. (c)(A) is true, but (R) is false.
4. (d)(A) is false, but (R) is true.
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(a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

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Q299 CBSE 2020

Define the term pollination. Differentiate between self pollination and cross pollination. What is the significance of pollination?

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Pollination moves pollen from anther to stigma, within one flower (self) or to another flower (cross), and makes fertilisation possible.
Pollination is the transfer of pollen grains from the anther (of the stamen) to the stigma (of the carpel). Self pollination: pollen is transferred from the anther to the stigma of the same flower. Cross pollination: pollen is transferred from the anther of one flower to the stigma of another flower, by agents such as wind, water or animals. Significance: pollination brings the male germ-cell to the female part of the flower, so that fertilisation can take place and a zygote is formed; the zygote grows into the embryo and the ovule develops into a seed.

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Q300 CBSE 2020
1. (a)List in tabular form two differences between binary fission and multiple fission.
2. (b)What happens when a mature Spirogyra filament attains considerable length.
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Binary fission gives two cells, multiple fission many; a mature Spirogyra filament fragments and each piece grows into a new filament.
(a) Binary fission: the parent cell divides into two daughter cells (its nucleus divides once). Multiple fission: the parent cell divides into many daughter cells at the same time (its nucleus divides repeatedly). Binary fission: takes place in favourable conditions. Multiple fission: can take place in favourable or unfavourable conditions. Other correct differences also earn credit. (b) The filament simply breaks up into smaller pieces (fragments), and each fragment grows into a new Spirogyra filament. This asexual mode of reproduction is called fragmentation.

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