Intext Questions

Q.1      What is the importance of DNA copying in reproduction?
Sol.        

Importance of DNA copying in reproduction are as follows –
(i)   DNA copying is the basis of inheritance of traits from parents to offspring.
(ii)  During copying of DNA, sometimes slight variations occur which form the basis for evolution.

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Q.2      Why is variation beneficial to the species but not necessarily for the individual ?
Sol.

Variation is beneficial to the species but not necessarily for the individual because sometimes variation in an individual may results in death of that individual but for species variation results in the existence of that species. For example, if there is a population of certain bacteria living in normal climatic conditions and the temperature increases due to global warming, then most of these bacteria will not be able to tolerate excessive heat and hence die. But some bacteria which had variations to resist heat would survive and grow further. So, we can say, variation is beneficial to species but not necessarily for the individual.

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Page 133

Q.1      How does binary fission differ from multiple fission?
Sol.       

Binary fission :
(i)    It is the process of asexual reproduction, in which parent organism divides to form two new organisms.
       For eg. Amoeba-Amoeba reproduces by binary fission.

      Multiple fission :

(ii)   It is the process of asexual reproduction, in which parent organism divides to form many new  organisms.
       for eg. Plasmodium- Plasmodium reproduces by multiple fission.

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Q.2      How will an organism be benefited if it reproduces through spores?
Sol.

The spores are covered by thick wall that protects them from unfavorable conditions like lack of food, water or high temperature. But as the conditions become favorable these spores can grow to produce new plant.
So, an organism will be benefited if it reproduces through spores.

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Q.3      Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Sol.

Complex organisms have highly differentiated tissues and organs and not a single cell of a tissue is able to produce another type of tissue. For example, a dog is a complex multicellular organism and if we cut dog into two parts, then the cells of one part are not able to produce cells of other body part to produce a complete dog but in case of hydra (simple organism), regeneration takes place because cells in the cut body part are able to produce cells of other body parts.

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Q.4      Why is vegetative propagation practiced for growing some types of plants?
Sol.

Vegetative propagation is practiced for growing some types of plants because of following advantages –
(i) It is used to grow a plant in which viable seeds are not formed or very few seeds are produced.
      eg:- Orange, Banana, Pineapple.
(ii) It helps to introduce plants in new areas where the seed germination fails to produce mature plant
      due to change in environmental factors and the soil.
(iii) It is more rapid, easier and cheaper method.
(iv) By this method a good quality of a race or variety can be preserved.

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Q.5      Why is DNA copying an essential part of the process of reproduction?
Sol.

DNA contains the genetic information which transfers from parents to offspring and copying of DNA is the process in reproduction due to which genetic information transfers.

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Page 140

Q.1      How is the process of pollination different from fertilization?
Sol.

Pollination – In this process pollen grains are transferred from anther to stigma of same flower or another flower.
(i)    In this process no fusion of 2 cells take place.
        Fertilization – It is defined as the fusion of male and female gametes to form zygote.
(ii)   Fusion of 2 cells, male gamete and female gametes, take place.

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Q.2      How is the role of seminal vesicles and prostate gland?
Sol.     

Seminal vesicles and prostate gland are the part of male reproductive system and their functions are-
(i)     Both add their secretions to vas deferens which carries sperms from the testes, thus makes the transport of sperms easier.
(ii)    Provide nutrition to the sperms.

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Q.3      What are the changes seen in girls at the time of puberty?
Sol.

Changes seen in girls at the time of puberty are:
(i)    Mammary glands develop and increase in size.
(ii)   Menstruation starts.
(iii)  Hairs grow in armpits and pubic regions.
(iv)  Extra fat deposited in thighs and hips and in other body parts.

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Q.4      How does the embryo get nourishment inside the mother’s body?
Sol.

The embryo gets nourishment through placenta inside the mother’s body.
Placenta is disc-shaped tissue which connects the mother body and embryo.

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Q.5      If a woman is using a copper- T, will it help in protecting her from sexually transmitted disease?
Sol.        No, using a copper-T will not help a woman in protecting her from sexually transmitted disease.

Exercise

Q.1     Asexual reproduction takes place through budding in :
                  (a) Amoeba     (b) Yeast     (c) Plasmodium     (d) Leishmania
Sol.       (b) Yeast

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Q.2      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
Sol.         (c) Vas deferens.

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Q.3       The anther contains :
                     (a) Sepals       (b) Ovules   (c) Carpel            (d) Pollen grains
 Sol.         (d) Pollen grains

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Q.4       What are the advantages of sexual reproduction over asexual reproduction ?
Sol.

Advantages of Sexual Reproduction over asexual reproduction are :-
(i)It promotes diversity.
(ii)It results genetic variations.
(iii)It contributes to evolution of species.
(iv)It results in origin of new species.

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Q.5        What are the functions performed by testes in human beings?
Sol.          

Functions of Testes in human beings are :
(i)Formation of male gametes called sperms.
(ii)Formation of male sex hormone (testosterone).

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Q.6        Why does menstruation occur ?
Sol.           In human female, one mature egg forms each month from the onset of puberty.
                  When this egg is not fertilized then menstruation occur.

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Q.7        Draw a labeled diagram of the longitudinal section of a flower.
Sol. 

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Q.8       What are the different methods of contraception?
Sol.

Methods of contraception :-
(i) Use Barriers – It prevents the sperm to reach the egg. For eg. Condoms, Diaphragm.

(ii) Chemicals – There are various chemicals or medicines which act by changing the hormonal balance of the body, So that fertilization cannot occur.

(iii) Surgical – If vas deferens in male or fallopian tube in female is blocked , transfer of sperm or transfer of egg will be prevented respectively.

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Q.9       How are the modes of reproduction different in unicellular and multicellular organisms?
Sol.

Unicellular organisms reproduce by asexual methods like fission, budding while multicellular organisms reproduce by sexual method & asexual method both. For ex. Guava is a multicellular plant that reproduce by vegetative propagation and sexual reproduction.

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Q.10     How does reproduction help in providing stability to populations of species ?
Sol.

Reproduction is the process of producing new individuals of the same species by existing organisms of a species, so, it helps in providing stability to population of species by giving birth to new individuals as the rate of birth must be at par with the rate of death to provide stability to population of a species.

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Q.11     What could be the reasons for adopting contraceptive methods?
Sol.

Reasons for adopting contraceptive methods :-
(i)Helps in family planning (Birth control)
(ii)To avoid unwanted pregnancy.
(iii)It provides protection from sexually transmitted diseases like HIV.

Exemplar

Multiple Choice Questions

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

(1) Banana

(2) Dog

(3) Yeast

(4) Amoeba

(a) (2) and (4)

(b) (1), (3) and (4)

(c) (1) and (4)

(d) (2), (3) and (4)

Sol. (b) (1), (3) and (4)

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Q.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

Sol. (c) Anther and Ovary

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Q.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

Sol. (c) Pollination, fertilization, embryo, seedling

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

(1) Asexual reproduction involves only one parent

(2) Asexual reproduction does not involve gametes

(3) Asexual reproduction occurs before sexual reproduction

(4) Asexual reproduction occurs after sexual reproduction

(a) (1) and (2)

(b) (1) and (3)

(c) (2) and (4)

(d) (3) and (4)

Sol. (a) (1) and (2)

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Q.5 Characters transmitted from parents to offspring are present in

(a) Cytoplasm

(b) Ribosome

(c) Golgi bodies

(d) Genes

Sol. (d) Genes

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Q.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

Sol. (c) Both similarities and variations with parents

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Q.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

Sol. (a) They reproduce asexually

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Q.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.

Sol. (a) Breaking up of filaments into smaller bits

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

(a) Budding

(b) Reduction division

(c) Binary fission

(d) Multiple fission

Sol. (d) Multiple Fission

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Q.10 The correct sequence of reproductive stages seen in flowering plantsis

(a) Gametes, zygote, embryo, seedling

(b) Zygote, gametes, embryo, seedling

(c) Seedling, embryo, zygote, gametes

(d) Gametes, embryo, zygote, seedling

Sol. (a) Gametes, zygote, embryo, seedling

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Q.11 The number of chromosomes in parents and off springs 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

Sol. (b) Halving of chromosomes during gamete formation

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

(a) Filaments

(b) Hyphae

(c) Rhizoids

(d) Roots

Sol. (b) Hyphae

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Q.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

Sol. (b) Stem, roots and leaves

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

(1) Large number of spores

(2) Availability of moisture and nutrients in bread

(3) Presence of tubular branched hyphae

(4) Formation of round shaped sporangia

(a) (1) and (3)

(b) (2) and (4)

(c) (1) and (2)

(d) (3) and (4)

Sol. (c) (1) and (2)

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Q.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

Sol. (c) Pollen grain in anther and upper surface of stigma

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

(1) Flowers are always bisexual

(2) They are the sexual reproductive organs

(3) They are produced in all groups of plants

(4) After fertilisation they give rise to fruits

(a) (1) and (4)

(b) (2) and (3)

(c) (1) and (3)

(d) (2) and (4)

Sol. d) (2) and (4)

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

(1) They possess both stamen and pistil

(2) They possess either stamen or pistil

(3) They exhibit cross pollination

(4) Unisexual flowers possessing only stamens cannot produce fruits

(a) (1) and (4)

(b) (2), (3) and (4)

(c) (3) and (4)

(d) (1), (3) and (4)

Sol. (b) (2), (3) and (4)

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

(1) It requires two types of gametes

(2) Fertilisation is a compulsory event

(3) It always results in formation of zygote

(4) Offspring formed are clones

(a) (1) and (4)

(b) (1), (2) and (4)

(c) (1), (2) and (3)

(d) (1), (2) and (4)

Sol. (c) (1), (2) and (3)

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Q.19 In the given 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

Sol. (d) Radicle, cotyledon and plumule

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Q.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

Sol. (b) Genetic material comes from two parents of the same species

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Q.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

Sol. (d) Continue the species generation after generation

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Q.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

Sol. (c) Cracking of voice

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Q.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

Sol. (d) Menstruation

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Q.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

Sol. (b) Formation of sperm

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

(1) Formation of germ cells

(2) Secretion of testosterone

(3) Development of placenta

(4) Secretion of estrogen

(a) (1) and (2)

(b) (2) and (3)

(c) (3) and (4)

(d) (1) and (4)

Sol. (c) (3) and (4)

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Q.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

Sol. (a) testis → vasdeferens → urethra

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

(a) Syphillis

(b) Hepatitis

(c) HIV AIDS

(d) Gonorrhoea

Sol. (b) Hepatitis