CBSE Class 10 Science How do humans reproduce Sure Shot Questions C

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HOW DO ORGANISMS REPRODUCE?

Very Short Answer type Questions

Question. Why is DNA copying an essential part of the process of reproduction?
Answer : Cell multiplication is essential for reproduction either as a means of multiplication in unicellular organisms or as a means of development of multicellular body from a single celled zygote. Cell multiplication cannot occur without DNA replication or DNA copying because each new cell must carry the full DNA complement.

Question. Where is DNA found in the cell?
Answer : Nucleus, plastids and mitochondria.

Question. State what type of method is used for growing jasmine plant.
Answer : Layering, a type of artificial method of vegetative propagation.

Question. Define sexual reproduction.
Answer : It is a mode of reproduction in which offspring are formed by the process of formation and fusion of gametes.

Question. What is the effect of DNA copying which is not perfectly accurate in the reproductive process?.
Answer : It produces mutations which give rise to useful, harmful and neutral variations in the progeny.

Question. Name the parts where germ cells of a flower are located.
Answer : Male — in anther of stamen.
Female — in ovule of carpel.

Question. List two functions of ovary of human female reproductive system.
Answer : 1. Formation of ova
2. Secretion of hormones estrogen and progesterone.

Question. List two unisexual flowers.
Answer : Water Melon, Papaya.

Question. Name the organs producing
(i) male germ cells / sperms and
(ii) female germ cells / ova respectively in humans.
Answer : (i) Testis
(ii) Ovary.

Question. What is DNA?
Answer : DNA or deoxyribonucleic acid is a self replicating biochemical that is carrier of genetic informationfor expression of hereditary traits and transfer to the next generation.

Question. Name the type of fission carried out by Amoeba.
Answer : Binary fission.

Question. Name the method by which Hydra reproduces commonly. Is this method sexual or asexual?
Answer : Hydra reproduces commonly by budding (also regeneration). It is a method of asexual reproduction.

Question. Name the type of reproduction mostly seen in unicellular organisms.
Answer : Asexual reproduction through cell division as binary fission, multiple fission, sporulation, budding.

Question. What happens when a mature Spirogyra filament attains considerable length?
Answer : The elongated mature filament of Spirogyra breaks to form smaller pieces or fragments. The fragments grow to form mature filaments. .

Question. Write the full form of IUCD.
Answer : Intra-uterine contraceptive device.

Question. Name any two types of asexual reproduction.
Answer : Fission, Spore formation.

Question. How does Plasmodium reproduce? Is this method sexual or asexual?
Answer : 1. Multiple fission,
2. Asexual method.

Question. What is fertilisation? Where does it occur in a human female?
Answer : Fertilisation is the fusion of male and female gametes to form diploid zygote. In human female, it occurs in ampulla part of fallopian tube.

Question. Name the method by which Spirogyra reproduces under favourable conditions. Is this method sexual or asexual?
Answer : 1. Fragmentation
2. Asexual method.

Short Answer type Questions

5. Explain how ovary functions both as reproductive organ as well as endocrine gland.
Answer : Reproductive Organ. Ovary produces ova, one every lunar month for possible fertilization and formation of foetus.
Endocrine Gland. Maturing ova or follicles present in ovary secrete oestrogen (= estrogen) while empty follicle develops into corpus luteum that secretes progesterone.

2. Compare the vegetative propagation of Bryophyllum and Money plant.
Answer : In Bryophyllum, vegetative propagation occurs through the agency of leaves that fall on moist soil. In Money Plant, vegetative propagation occurs with the help of stem cuttings bearing at least one leaf and its axillary bud. A single leaf of Bryophyllum can produce several plants. A leafy stem cutting of Money Plant forms only a single plant.

7. (a) Why are budding, fragmentation and regeneration considered as asexual type of reproduction?
(b) Which among the following reproduces by spore formation: Bryophyllum, Rhizopus, Hydra ?
Answer : (a) Asexual Reproduction: Budding, fragmentation and regeneration are all considered to be modes of asexual reproduction as they involve formation of new individuals from single parents without fertilization or fusion of gametes.
(b) Rhizopus.

3. (a) Where are the male germ cell and female gamete produced in a flower ?
(b) State the significance of variation in reproduction.
(c) Mention the principle of regeneration.
Answer : (a) Male Germ Cell (Male Gamete). Formed inside the pollen tube or pollen grain from generative cell.
Female Gamete (Oosphere). Inside embryo sac part of ovule.
(b) Significance of Variation in Reproduction
1. It provides individuality to each living organism,
2. It helps individuals in the struggle for existence,
3. Variation is a source of preadaptation.
(c) Principle of Regeneration: It is the ability of an individual to form lost or broken part, sometimes the entire individual from a piece of the parent body through dedifferentiation of mature cells and activity of reserve cells. The ability to form a new individual from a part of the body is well developed in simple animals like Hydra and Planaria. It is restricted to the formation of only broken parts in complex organisms.

4. (a) Name two bacterial STD infections.
(b) How do oral pills prevent pregnancy?
Answer : (a)
i. Gonorrhoea caused by bacterium Neisseria gonorrhoeae
ii. Syphilis caused by bacterium Treponema pallidum.
(b) Oral pills contain progestin (= progesterone) alone or in combination with estrogen. They prevent pregnancy by inhibition of ovulation, making uterine wall unsuitable for implantation alongwith unsuitable changes in cervical mucus and activity of fallopian tubes.

1. What is placenta? State its two roles during pregnancy.
Answer : Placenta is a spongy vascular structure formed by the joint activity of maternal and foetal tissues in the wall of uterus that connects foetus with uterus.
Roles:
1. Providing nutrition to the foetus.
2. Taking away wastes of the foetus.

6. What is the information source in the cell nucleus for making proteins. State the basic events in reproduction.
Answer : 1. Information Source. DNA
2. Basic Events in Reproduction. DNA replication, growth of cellular machinery and cell division.

Long Answer type Questions

8. Draw labelled diagram of
(a) Spore formation in Rhizopus
(b) Regeneration in Planaria.
Answer : (a)

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

(i) banana

(ii) dog

(iii) yeast

(iv) Amoeba

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

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, fertilisation

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)

5. Characters transmitted from parents to offspring are present in

(a) cytoplasm

(b) ribosome

(c) golgi bodies

(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

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

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.

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

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

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

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

(a) filaments

(b) hyphae

(c) rhizoids

(d) roots

13. Vegetative propagation refers to 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

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)

15. Length of pollen tube depends on the distance between

(a) pollen grain and upper surface of stigma

(b) pollen grain on 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

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)

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)

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 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)

19. In the below Figure, 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

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

21. Reproduction is essential for living organisms in order to

(a) keep the individual organism alive

(b) fulfill their energy requirement

(c) maintain growth

(d) continue the species generation after generation

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

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

(a) growth of body

(b) changes in hair pattern

(c) change in voice

(d) menstruation

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

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)

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

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

(a) Syphillis

(b) Hepatitis

(c) HIV - AIDS

(d) Gonorrhoea

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

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

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

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

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

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

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

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