NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce

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Written by Team Trustudies
Updated at 2021-05-07


NCERT solutions for class 10 Science Chapter 8 How Do Organisms Reproduce Exercise

Q1 ) Asexual reproduction takes place through budding in
(a) amoeba

(b) yeast

(c) plasmodium

(d) leishmania



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

(b) Yeast

Q2 ) 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



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

(c) Vas deferens

Q3 ) The anther contains
(a) sepals

(b) ovules

(c) carpel

(d) pollen grains



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

(d) Pollen grains

Q4 ) What are the advantages of sexual reproduction over asexual reproduction ?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

In asexual reproduction, there is no much genetic variation as the offspring are almost identical to their parent because they have the same genes as their parent.This inhibits the further evolution of the organism hence seen as an disadvantage whereas in sexual reproduction even if the offspring is quite similar to their parents, they are not identical to them or to one another because the offspring receive some genes from the mother and some from the father. There is a greater genetic variation because of the mixing of genes of mother and father in various different combinations. In this way, sexual reproduction leads to a greater variety in population which means that a species (animal or plant) can adapt quickly to changes in its surroundings.

Q5 ) What are the functions performed by testes in human beings?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

The functions of testes in humans are following :
(i) After the stage of adolescence, testes produce male gametes(sperms) in the human males.

(ii)testes produce male sex hormone called testosterone. Testosterone takes care of the development of reproductive organs and secondary sexual characters in boys.

Q6 ) Why does menstruation occur ?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

In human females, one mature egg forms each month from the onset of puberty.If the egg does not get fertilized (due to non-availability of sperm in the female body) then the inner linings of the uterus which are thick and soft is no longer needed and hence it breaks. So, these linings of the uterus along with the blood vessels and the dead ovum (or egg) comes out of the vagina in the form of blood called menstruation. Menstruation occurs after the interval of every 28 days and the time period between ovulation and menstruation is about 14 days.

Q7 ) Draw a labeled diagram of the longitudinal section of a flower.



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Q8 ) What are the different methods of contraception?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

The different methods of contraception are as follow :
(i)Barrier method : In this method,during sexual intercourse condom, diaphragm and cervical caps are used which prevent the entry of sperms in the female genital tract.

(ii)Chemical method: In this method a woman uses two kinds of pills- oral and vaginal pills. The oral pills suppress the release of ovum in the fallopian tube. These are called oral contraceptives. The vaginal pills/ creams are spermicidal which contain chemicals that kill the sperms during their journey in the vaginal tract.

(iii)Intrauterine contraceptive devices: Intrauterine contraceptive devices like copper-T are placed safely in the uterus by a skilled doctor which prevents the sperms from reaching the uterus.

(iv)Surgical method: In this method, a small part of vas deferens of male and fallopian tube of female is cut or tied by surgery. It is called vasectomy in males and tubectomy in females.

Q9 ) How are the modes of reproduction different in unicellular and multicellular organisms?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Reproduction mode in unicellular organisms:
(i) Asexual reproduction takes place in unicellular organisms like fission, budding etc.

(ii) Only one organism is required in this method.

(iii) No special cells and organs are present for reproduction.

Reproduction mode in multicellular organisms:
(i) Sexual reproduction takes place in multicellular organisms.

(ii) A male and a female both are required in this method.

(iii) Special cells and special organs are present for reproduction.

Q10 ) How does reproduction help in providing stability to populations of species ?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Reproduction is the process in which new individuals of the same species are produced by existing organisms ,so it helps in maintaining the stability to the population of a species.Also the introduction of genetic variation during reproduction helps in preventing them from getting wiped out during adverse conditions.

Q11 ) What could be the reasons for adopting contraceptive methods ?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

The reasons for adopting contraceptive methods are listed as:
(i) To control the increase in population by controlling the birth rate.

(ii)To avoid unwanted pregnancy.

(iii) To provide protection from sexually transmitted diseases like HIV.

NCERT solutions for class 10 Science Chapter 8 How Do Organisms Reproduce Intext Exercise

Q1 ) What is the importance of DNA copying in reproduction?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

The importance of DNA copying in reproduction are:
(i) DNA copying is the basis of inheritance of traits transferring from parents to offspring by which the characteristics of species and continuity of life are maintained.

(ii) During copying of DNA, sometimes variations are produced in organisms which is the basis for evolution of new species.

Q2 ) Why is variation beneficial to the species but not necessarily for the individual?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Variations can be beneficial or harmful depending upon the ecological niche of the organism.Nature of evolution selects the variation suitable for the particular niche. Thus variations are necessary for the survival of the species. But sometimes variation in an individual may result in death of that individual or the individuals who are not evolved also die due to non-favorable conditions of the change in surroundings.So collectively we can say that variation are beneficial to the species but not necessarily for the individual.For e.g. If the temperature of water increases by global warming the population of heat resistant bacteria in water will survive but most other bacteria would die.

Q3 ) How does binary fission differ from multiple fission?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Binary fission: It is the process of asexual reproduction, in which parent organism divides to form two new organisms.It generally occurs in favourable conditions. For e.g. Amoeba-Amoeba reproduces by binary fission.



Multiple fission: It is the process of asexual reproduction, in which parent organism divides to form two or more new organisms. It can take place in unfavourable conditions too. for eg. Plasmodium- Plasmodium reproduces by multiple fission.


Q4 ) How will an organism be benefited if it reproduces through spores?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Spores are covered by a thick layer that protects them in adverse conditions like lack of food, water or high temperature. When the favourable conditions occur, these spores start to grow again. So an organism can be benefited if it reproduces through spores.

Q5 ) Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Complex multicellular organisms have highly differentiated tissues made by specialised cells and tissue combinedly makes organs and then collectively an organ system is formed by organs. So this says that a single cell of a tissue is not able to reproduce another type of tissue in complex multicellular organisms. For example, a dog is a complex multicellular organism and if we cut the dog into two parts, then the cells of one part won’t be able to reproduce cells of the other part to produce a complete dog .

Q6 ) Why is vegetative propagation practiced for growing some types of plants?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Vegetative propagation is done for growing such plants which usually do not produce seeds or produce plants in which viable seeds are not formed or very few seeds are produced.

e.g:- Orange, Banana, Pineapple.Also it is an easier, rapid and cheaper method and a good quality of a race or variety can be preserved even in the areas where seed germination fails to produce mature plants.

Q7 ) Why is DNA copying an essential part of the process of reproduction?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

DNA contains the genetic information.It is an essential part of the process of reproduction to transfer the characteristics of the parent organisms to the offspring and also some variations are to be produced in the offspring due to change in DNA copying which provide an organism the capability to survive in changing conditions.

Q8 ) How is the process of pollination different from fertilization?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Pollination- In this process by which pollen grains are transferred from the anther of a stamen to the stigma of a carpel of the same flower or another flower.It takes place by various pollinating agents.
Fertilization- It is defined as the fusion of male gamete present in pollen grain and female gamete (or egg) present in ovule to form zygote.It takes place by natural or artificial ways.

Q9 ) How is the role of seminal vesicles and prostate gland?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Seminal vesicles and prostate gland are part of the male reproductive system. They both add their secretion to vas deferens which carries sperms from the testes,thus making the transport of sperms much easier. This secreted fluid provides nutrition to sperms in the form of fructose, calcium and some enzymes and also protects the sperms from the acids present in the urethra.

Q10 ) What are the changes seen in girls at the time of puberty?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

At the time of puberty changes seen in girls are:
(i)Mammary glands(or breasts) develop and enlarge.

(ii)Menstruation(monthly periods) starts.

(iii)Hairs grow in armpits and pubic regions.

(iv)Extra fat deposited in thighs and hips and in other body parts and the hips gets broadened.

(v)Fallopian tube, uterus and vagina enlarge and feelings and sexual drives associated with adulthood begin to develop .

Q11 ) How does the embryo get nourishment inside the mother’s body ?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

The embryo gets nourishment through a disc-shaped tissue called placenta which contains villi and connects the mother body and embryo.There are empty spaces in mother’s tissues that cover the villi. It provides a large surface area for the transfer of glucose, oxygen and other substances from the mother to the embryo.

Q12 ) If a woman is using a copper- T, will it help in protecting her from sexually transmitted disease?



NCERT Solutions for Class 10 Science Chapter 8 How Do Organisms Reproduce


Answer :

Copper-T cannot prevent a woman from sexually transmitted diseases as it is a contraceptive method which prevents implantation of the zygote inside the uterus. These diseases are transmitted by contact which cannot be prevented by using it.



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