NCERT Exemplar Class 10 Science Chapter 8 How Do Organisms Reproduce

Chapter 8 How Do Organism Reproduce NCERT Exemplar for class 10 Science

The NCERT Exemplar Class 10 Science Chapter 8 How Do Organisms Reproduce? is an important study resource for CBSE Class 10 students. This Exemplar can help them to clear their doubts and understand the concepts in an interactive way. NCERT Exemplar Solution Class 10 Science will cover important concepts that are more likely to be asked in examinations. Hence, students are advised to go through the NCERT Exemplar to ace their examinations.

These NCERT Class 10 Science Exemplar Solutions are prepared according to the latest CBSE Syllabus 2023-24. It has answers to 27 MCQs, 21 short answer questions 11 long answer questions which will help you to practise questions of varying difficulty on the reproduction of organisms. NCERT Exemplar Solutions Class 10 Science Chapter 8 provide an overview of the main concepts in the chapter and helps you to get well-versed in important topics from the chapter.

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NCERT Exemplar For Class 10 How Do Organism Produce

1. In the list of organisms given below, those that reproduce by the asexual method are

(i) banana

(ii) dog

(iii) yeast

(iv) Amoeba

(a) (ii) and (iv)

(b) (i), (iii) and (iv)

(c) (i) and (iv)

(d) (ii), (iii) and (iv)

Soln:

Answer is (b) (i), (iii) and (iv)

Explanation:

Dog reproduce sexually, yeast reproduce by budding, Amoeba reproduce sexually and cultivated banana also reproduce asexually.

2. In a flower, the parts that produce male and female gametes (germ cells) are

(a) stamen and anther

(b) filament and stigma

(c) anther and ovary

(d) stamen and style

Soln:

Answer is (c) anther and ovary

3. Which of the following is the correct sequence of events of sexual reproduction in a flower?

(a) pollination, fertilisation, seedling, embryo

(b) seedling, embryo, fertilisation, pollination

(c) pollination, fertilisation, embryo, seedling

(d) embryo, seedling, pollination, fertilization

Soln:

Answer is (c) pollination, fertilisation, embryo, seedling

Explanation:

Pollination leads to fertilization after which embryo is formed. Seedling comes out from embryo.

4. Offspring formed by asexual method of reproduction have greater similarity among themselves because

(i) asexual reproduction involves only one parent

(ii) asexual reproduction does not involve gametes

(iii) asexual reproduction occurs before sexual reproduction

(iv) asexual reproduction occurs after sexual reproduction

(a) (i) and (ii)

(b) (i) and (iii)

(c) (ii) and (iv)

(d) (iii) and (iv)

Soln:

Answer is (a) (i) and (ii)

Explanation:

Asexual reproduction involve single parent and there will be no exchange of gametes hence offspring looks similar to their parent.

5. Characters transmitted from parents to offspring are present in

(a) cytoplasm

(b) ribosome

(c) Golgi bodies

(d) genes

Soln:

The answer is (d) genes

6. Characters that are transmitted from parents to offspring during reproduction show

(a) only similarities with parents

(b) only variations with parents

(c) both similarities and variations with parents

(d) neither similarities nor variations

Soln:

Answer is (c) both similarities and variations with parents

7. A feature of reproduction that is common to Amoeba, Spirogyra and Yeast is that

(a) they reproduce asexually

(b) they are all unicellular

(c) they reproduce only sexually

(d) they are all multicellular

Soln:

Answer is (a) they reproduce asexually

Explanation:

Amoeba reproduce by binary fission, Spirogyra reproduce by fragmentation, yeast reproduce by budding.

8. In Spirogyra, asexual reproduction takes place by

(a) breaking up of filaments into smaller bits

(b) division of a cell into two cells

(c) division of a cell into many cells

(d) formation of young cells from older cells.

Soln:

Answer is (a) breaking up of filaments into smaller bits

Explanation:

Spirogyra reproduce by fragmentation. Spirogyra simply breaks up into smaller pieces upon maturation. These pieces or fragments grow into new individuals

9. The ability of a cell to divide into several cells during reproduction in Plasmodium is called

(a) budding

(b) reduction division

(c) binary fission

(d) multiple fission

Soln:

The answer is (d) multiple fission

Explanation:

Plasmodium divide into many daughter cells by binary multiple fission. In Multiple fission nucleus of the cell divides multiple times by mitosis then separates to create multiple daughter cells.

10. The correct sequence of reproductive stages seen in flowering plants is

(a) gametes, zygote, embryo, seedling

(b) zygote, gametes, embryo, seedling

(c) seedling, embryo, zygote, gametes

(d) gametes, embryo, zygote, seedling

Soln:

Answer is (a) gametes, zygote, embryo, seedling

Explanation:

Gametes fuse to form a zygote during fertilization. After fertilization-embryo will be formed which will lead to seedling in plants.

11. The number of chromosomes in parents and offsprings of a particular species remains constant due to

(a) doubling of chromosomes after zygote formation

(b) halving of chromosomes during gamete formation

(c) doubling of chromosomes after gamete formation

(d) halving of chromosomes after gamete formation

Soln:

The answer is (b) halving of chromosomes during gamete formation

Explanation:

The halving of chromosome during gamete formation number of chromosome remain same as the somatic cell of an organism. Halving of gametes in a chromosomes is called the diploid number of chromosomes.

12. In Rhizopus, tubular thread-like structures bearing sporangia at their tips are called

(a) filaments

(b) hyphae

(c) rhizoids

(d) roots

Soln:

The answer is (b) hyphae

Explanation:

Tiny blob-on-a-stick like structures involved in reproduction are called hyphae. The blobs are called sporangia, which contain cells, or spores, that can eventually develop into new Rhizopus individuals.

13. Vegetative propagation refers to the formation of new plants from

(a) stem, roots and flowers

(b) stem, roots and leaves

(c) stem, flowers and fruits

(d) stem, leaves and flowers

Soln:

The answer is (b) stem, roots and leaves

Explanation:

Vegetative propagation is a type of asexual reproduction occurs in plants. In vegetative reproduction new plant is produced from vegetative parts of the plants such as roots, stem, leaf and buds. In vegetative reproduction plants produced are genetically similar enough to the parent plant to have all its characteristics.

14. Factors responsible for the rapid spread of bread mould on slices of bread are

(i) large number of spores

(ii) availability of moisture and nutrients in bread

(iii) presence of tubular branched hyphae

(iv) formation of round shaped sporangia

(a) (i) and (iii)

(b) (ii) and iv)

(c) (i) and (ii)

(d) (iii) and (iv)

Soln:

Answer is (c) (i) and (ii)

Explanation:

A large number of spores ensure a few spores survive even in adverse conditions. Availability of moisture and nutrients in the bread provides the necessary environment for the spore to grow into mould.

15. Length of pollen tube depends on the distance between

(a) pollen grain and the upper surface of the stigma

(b) pollen grain on the upper surface of stigma and ovule

(c) pollen grain in anther and upper surface of stigma

(d) upper surface of stigma and lower part of style

Soln:

The answer is (d) upper surface of stigma and lower part of style

Explanation:

Length of pollen tube ensures pollens reach the stigma to conduct pollination.

16. Which of the following statements are true for flowers?

(i) Flowers are always bisexual

(ii) They are the sexual reproductive organs

(iii) They are produced in all groups of plants

(iv) After fertilisation, they give rise to fruits

(a) (i) and (iv)

(b) (ii) and (iii)

(c) (i) and (iii)

(d) (ii) and (iv)

Soln:

Answer is (d) (ii) and (iv)

Explanation:

Flowers are not always bisexual hence statement i) is wrong. Only angiosperms produce flowers hence statement iii) is wrong.

17. Which among the following statements are true for unisexual flowers?

(i) They possess both stamen and pistil

(ii) They possess either stamen or pistil

(iii) They exhibit cross-pollination

(iv) Unisexual flowers possessing only stamens cannot produce fruits

(a) (i) and (iv)

(b) (ii), (iii) and (iv)

(c) (iii) and (iv)

(d) (i), (iii) and (iv)

Soln:

Answer is (b) (ii), (iii) and (iv)

Explanation:

Cross-pollination is necessary is unisexual flowers as they possess either stamen or pistil. Flowers possessing only stamens cannot produce fruits because fruit is a mature ovary.

18. Which among the following statements are true for sexual reproduction in flowering plants?

(i) It requires two types of gametes

(ii) Fertilisation is a compulsory event

(iii) It always results in the formation of zygote

(iv) Offspring formed are clones

(a) (i) and (iv)

(b) (i), (ii) and (iv)

(c) (i), (ii) and (iii)

(d) (i), (ii) and (iv)

Soln:

Answer is (c) (i), (ii) and (iii)

Explanation:

Off-springs produced from sexual reproduction cannot be clones hence statement iv) is wrong.

19. In Figure 8.1, the parts A, B and C are sequentially

(a) cotyledon, plumule and radicle

(b) plumule, radicle and cotyledon

(c) plumule, cotyledon and radicle

(d) radicle, cotyledon and plumule

Soln:

Answer is (c) plumule, cotyledon and radicle

20. Offspring formed as a result of sexual reproduction exhibit more variations because

(a) sexual reproduction is a lengthy process

(b) genetic material comes from two parents of the same species

(c) genetic material comes from two parents of different species

(d) genetic material comes from many parents

Soln:

The answer is (b) genetic material comes from two parents of the same species

Explanation:

In sexual reproduction zygote is formed by gametes produces by a male and a female. A male and a female gamete fuse to form a zygote which fertilizes to produce new offspring. Because of the contribution of two parents, off-springs incur more variations.

21. Reproduction is essential for living organisms in order to

(a) keep the individual organism alive

(b) fulfil their energy requirement

(c) maintain growth

(d) continue the species generation after generation

Soln:

The answer is (d) continue the species generation after generation

Explanation:

Reproduction is essential to the lineage of the species whereas other life processes are essential to keep the organism alive.

22. During adolescence, several changes occur in the human body. Mark one change associated with sexual maturation in boys

(a) loss of milk teeth

(b) increase in height

(c) cracking of voice

(d) weight gain

Soln:

Answer is (c) cracking of voice

Explanation:

During adolescence Following changes occur in boys

• Growth of hairs in new parts of the body such as armpits, on the chest and between thighs near genital organ face, legs and on arms.
• Creaking of voice
• Skin becomes oily and pimples will start appearing
• Occasionally penis will erect especially while dreaming.

23. In human females, an event that reflects the onset of the reproductive phase is

(a) growth of body

(b) changes in hair pattern

(c) change in voice

(d) menstruation

Soln:

The answer is (d) menstruation

Explanation:

During adolescence Following changes occur in boys

• Growth of hairs in new parts of the body such as armpits, between thighs near genital organ thin hairs on face, legs and on arms.
• Start menstruation
• Skin becomes oily and pimples will start appearing
• Breast size will increase

24. In human males, the testes lie in the scrotum, because it helps in the

(a) process of mating

(b) formation of sperm

(c) easy transfer of gametes

(d) all the above

Soln:

The answer is (b) formation of sperm

Explanation:

Testes lying in the scrotum ensures the temperature of the testes remain lower than the body temperature. This helps in sperm production.

25. Which among the following is not the function of testes at puberty?

(i) formation of germ cells

(ii) secretion of testosterone

(iii) development of placenta

(iv) secretion of estrogen

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)
(d) (i) and (iv)

Soln:

Answer is (c) (iii) and (iv)

Explanation:

Testis is a male reproductive organ but estrogen is produced in females. Placenta is formed in females during pregnancy.

26. The correct sequence of organs in the male reproductive system for transport of sperms is

(a) testis → vasdeferens → urethra

(b) testis → ureter → urethra

(c) testis → urethra → ureter

(d) testis → vasdeferens → ureter

Soln:

Answer is (a) testis → vasdeferens → urethra

Explanation:

Testis produces sperm which is transferred into epididymis through vasdeferns. From vasdeferens sperm is taken to urethra.

27. Which among the following diseases is not sexually transmitted?

(a) Syphillis

(b) Hepatitis

(c) HIV – AIDS

(d) Gonorrhoea

Soln:

The answer is (b) Hepatitis

Explanation:

Hepatitis spread through contaminated water and food.

Short Answer Questions

28. In a bisexual flower in spite of the young stamens being removed artificially, the flower produces fruit. Provide a suitable explanation for the above situation.

Soln:

When stamens of a bisexual flower are removed. Cross-pollination can take place which results in fertilization and production of fruit.

29. Can you consider cell division as a type of reproduction in unicellular organism? Give one reason.

Soln:

Reproduction is the creation of a new individual. In unicellular organism cell division leads to the formation of new individuals. Hence cell division is a type of reproduction in unicellular organisms.

30. What is a clone? Why do offsprings formed by asexual reproduction exhibit remarkable similarity?

Soln:

Clone are the aggregate of cell or organisms which are produced asexually. Asexual reproduction involve single parent and there will be no exchange of gametes hence offspring looks similar to their parent.

31. Explain how, offspring and parents of organisms reproducing sexually have the same number of chromosomes?

Soln:

Because of the halving of the chromosome during gamete formation number of chromosome remain same as somatic cell of an organism. Halving of gametes in a chromosomes is called a diploid number of chromosomes.

32. Colonies of yeast fail to multiply in water, but multiply in sugar solution. Give one reason for this.

Soln:

Yeast requires energy for its growth and cell division. Water does not provide required energy whereas sugar provides energy hence yeast multiplies in sugar solution.

33. Why does bread mould grow profusely on a moist slice of bread rather than on a dry slice of bread?

Soln:

Spores of bread mould needs moisture to germinate and grow. Hence mould grow profusely on a moist slice of bread.

34. Give two reasons for the appearance of variations among the progeny formed by sexual reproduction.

Soln:

• Gametes are contributed by two individuals of the same species.
• Crossing over occur during meiosis.

35. In the tobacco plant, the male gametes have twenty-four chromosomes. What is the number of chromosomes in the female gamete? What is the number of chromosomes in the zygote?

Soln:

Number of chromosomes in both the gametes are equal hence a number of chromosomes in a female gamete of tobacco plant is 24. Combining both number of chromosomes in a zygote is 48.

36. Why cannot fertilisation take place in flowers if pollination does not occur?

Soln:

Pollination is a process in which transfer of pollen grains from anthers to stigma takes place. If there is no pollination then there will be no fusion of gametes and fertilization do not take place.

37. Is the chromosome number of the zygote, embryonal cells and adult of a particular organism always constant? How is the constancy maintained in these three stages?

Soln:

Meiosis is a way of cell division in which a number of chromosomes get halved. After fertilization chromosomes become equal to that of somatic cells. After fertilization Mitosis takes place for the rest of the stages of life. Hence chromosomes remain constant.

38. Where is the zygote located in the flower after fertilization?

Soln:

After fertilization zygote will be located in the ovary.

39. Reproduction is linked to stability of population of a species. Justify the statement.

Competition for food, predation is common in nature. If there is no reproduction species would have become extinct. Hence reproduction linked to population of the species.

40. How are general growth and sexual maturation different from each other?

Soln:

General growth is all about growth of size. Sexual maturation is about achieving the ability to reproduce. General growth begins with the growth of an organism whereas sexual maturity is attained at a certain stage of life called adolescence.