Important Questions for CBSE Class 10 Science Chapter 8 - How do Organisms Reproduce? 2024-25

Very Short Answer Questions (1 Mark)

1. In vegetative reproduction, the new individuals are genetically –

1. Similar

2. Dissimilar

3. Abnormal

4. None of these

Ans: a) Similar

2. When an organism breaks into a number of parts and each part develop into an individual, it is called –

1. Budding

2. Binary fission

3. Regeneration

4. Spore formation

Ans: c) Regeneration

3. In Female, fertilization of ovum takes place in

1. Vagina

2. Ovary

3. Uterus

4. Fallopian tubes

Ans: d) Fallopian tubes

4. Define parthenogenesis.

Ans: Parthenogenesis is the process of development of an organism from an unfertilized egg.

5. How many male gametes are produced by pollen grains?

Ans: Two gametes are produced by pollen grains.

6. During grafting, the portion of plant that is grafted is called –

1. Stock

2. Scion

3. Stalk

4. Stem

Ans: b) Scion

7. Which part of the flower forms the fruit?

1. Whole flower

2. Only stamens and carpel

3. Only ovary

4. Only carpel

Ans: c) Only ovary

8. Anemophily is the pollination by –

1. Birds

2. Rain

3. Insects

4. Wind

Ans: d) Wind

9. What is syngamy?

Ans: Fusion of male gamete with the egg cell is called syngamy.

10. Name the structure through which pollen tubes enter the ovule.

Ans: Pollen tubes enter the ovule through stigma.

11. A common feature of reproduction in Amoeba, spirogyra and yeast is that –

1. Asexual reproduction occurs after sexual reproduction

2. Asexual reproduction occurs before sexual reproduction

3. Asexual reproduction does not involve gametes

4. Asexual reproduction involves only one parent

Ans: d) Asexual reproduction involves only one parent.

12. The normal duration of menstrual cycle is

1. 7 – 8 days

2. 13 – 15 days

3. 3 – 4 days

4. 28 days

Ans: d) 28 days

13. Which of the following is an IUCD?

1. Copper – T

2. Diaphragm

3. Oral pills

4. Tubectomy

Ans: a) Copper – T

14. What is parturition?

Ans: Parturition is the process of birth of a fully developed fetus in completion of gestation.

15. What is puberty?

Ans: Puberty is the process of physical changes when the reproductive system is functionally active or starts producing ova or sperm.

16. Fertilization in plants occurs in the –

1. Embryo sac

2. Style

3. Pollen tube

4. Stigma

Ans: a) Embryo sac

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

1. Only similarities with parents

2. Only variations with parents

3. Neither similarities nor variations

4. Both similarities and variations with parents

Ans: d) Both similarities and variations with parents

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

1. Syphilis

2. Gonorrhea

3. HIV – AIDS

4. Hepatitis

Ans: d) Hepatitis

19. What is tubectomy?

Ans: Tubectomy is the permanent method of contraception in women by removal of a section of fallopian tube.

20. Name the causative organism of AIDS?

Ans: The causative organism of AIDS is HIV – Human Immunodeficiency virus.

21. A common feature of reproduction in Amoeba, spirogyra and yeast is that –

1. They reproduce only sexually

2. They are all unicellular

3. They reproduce asexually

4. They are all multicellular

Ans: c) They reproduce asexually

22. Which of this is seminal fluid?

1. Prostate gland

2. Cowper’s gland

3. Seminal vesicle

4. All of these

Ans: c) Seminal vesicle

23. At the time of entering into ovule, pollen tube has

1. Three male nuclei

2. Two male nuclei

3. One gamete nucleus

4. Four male gametes

Ans: b) Two male nuclei

24. How many follicles mature every month during the reproductive phase of human females?

Ans: One egg is produced every month during the reproductive phase by one of the ovaries.

25. What is the product of fertilization?

Ans: The product of fertilization is zygote.

26. Asexual reproduction takes place through budding in

1.  Amoeba

2.  Yeast

3.  Plasmodium

4.  Leishmanial

Ans: (b) Yeast

27. Which of the following is not a part of the female reproductive system in human beings?

1.  Ovary

2.  Uterus

3.  Vas deferens

4.  Fallopian tube

Ans: (c) Vas deferens

28. The anther contains

1.  Sepals

2.  Ovules

3.  Carpel

4.  Pollen grains

And) Pollen grains

29. The simple animals such as planaria can be cut into a number of pieces and each piece grows into a complex organism. What is this process known as?

Ans: The process of cutting an animal into a number of pieces and each piece grows into a complex organism is known as regeneration.

30. Name the unicellular organism which caused the disease known as kala-azar.

Ans: Leishmania is the organism causing the disease known as kala-azar.

31. Which process taking place in the nucleus of a cell leads to variation in the offspring during reproduction?

Ans: DNA copying taking place in the nucleus of a cell leads to variation in the offspring during reproduction.

32. Which type of layering is done in Jasmine?

Ans: Air Layering (Gootee) is done in jasmine.

33. Where does fertilization take place in a human female?

Ans: Fertilization takes place in the oviduct (fallopian tube).

Short Answer Question (2 Marks)

1. Define reproduction. Why is it important?

Ans: Reproduction is the process of producing new organisms of the same kind. It is important to increase the population of individuals and maintain continuity of life. Without reproduction organisms become extinct.

2. What is callus?

Ans: In artificial vegetative propagation, an isolated plant structure called explants is cultivated in a glass container under aseptic conditions with proper nutrient medium. The explants become identical masses of cells called callus.

3. What happens if the mature ovum is not fertilized in a female? Name the process.

Ans: If mature ovum is not fertilized in a female it gets released into fallopian tubes. This process is known as menstruation.

4. Give two examples each of IUD and STD.

Ans: Examples of IUCD are Copper–T and loops. Examples of STD are Syphilis and gonorrhea.

5. What do you understand by self-pollination & cross pollination? Give examples of each.

Ans: In self pollination the pollen is transferred from the stamen to the stigma in the same flower. Examples of self pollination are wheat, rice etc.

In cross pollination pollen is transferred from one flower to another. The pollen is transferred through wind, water or animals. Examples of cross pollination are plums, blackberries etc.

6. What is the difference between binary fission and multiple fission?

Ans: The difference between binary fission and multiple fission is as follows:

7. What are the basic features of asexual reproduction?

Ans: Basic feature for asexual reproduction are as follows:

• In asexual reproduction only one organism is involved.

• In asexual reproduction cell divisions are either amitotic or mitotic.

• Formation of gametes and their fertilization does not occur in asexual reproduction.

• The process takes a short time and new organisms are naturally alike to their parents.

8. What is a clone? Why do offspring’s formed by asexual reproduction exhibit remarkable similarity?

Ans: Cells derived from a standard ancestor are referred to as clones. Offspring obtained from gametogenesis has just one parent; there are not any chances of variation in their chromosomes. Hence, they are exactly similar to their parents.

9. List two important functions of gonads.

Ans: Two important functions of gonads are production of gametes in male and female and production of sex hormones.

10. What is the function of the cowper's gland and prostate gland?

Ans: Function of Cowper’s glands is the secretion of a white, viscous and alkaline secretion lubricant.

Function of Prostate gland is to keep the sperm active and mobile.

11. List various reproductive parts of the flower.

Ans: Reproductive organs of flower are sepals, petals, stamens and pistils.

Stamen is the male reproductive part also known as androecium.

Pistil is the female reproductive part and made up of three parts named ovary, style and stigma. Pistils are also known as carpel and collectively known as gynoecium.

12. What is the difference between internal & external fertilization?

Ans: Difference between internal and external fertilization is as follows:

13. Name the type of reproduction involved in the following –

(i) A slice of bread has greenish – yellow patches.

Ans: Greenish yellow patches on a slice of bread are due to spore formation.

(ii) Potato in the store room starts sprouting

Ans: Potato in the store room starts sprouting due to vegetative propagation.

14. Give two reasons for the appearance of variations among the offsprings formed by sexual reproduction.

Ans: An offspring formed by sexual reproduction has variations because it involves two parents; therefore the offspring has some characteristics of male and a few of female. Copying DNA isn't exactly the same as a parent.

15. Name the organism that causes syphilis. Mention two symptoms.

Ans: Syphilis is caused by bacteria. First stage causes sore on the mouth and genitals. Sometimes symptoms may include muscle aches, fever and burning sensation at urination.

16. How does a human foetus derive nutrition?

Ans: A special disc-like structure is made between the embryo and the uterus wall called placenta. It is a link between the mother and the foetus. This disc remains embedded within the uterine wall. It has villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi. This provides an outsized area for the transfer of nutrients mother to foetus.

17. Why are testes and ovaries considered as primary sex organs?

Ans:  Testes and ovaries produce gametes and sex hormones so they are called primary sex organs.

18. What is the difference between fission and budding?

Ans: Difference between fission and budding is as follows:

19. Mention function of testis in humans?

Ans: Function of testes is as follows:

• Testes produce male gametes sperm, a process known as spermatogenesis.

• Testes secrete male sex hormone testosterone which helps in regulation of spermatogenesis and also keeps structure and function of secondary sex types like facial, axial and public hair, voice moustache, etc.

20. Why does menstruation occur?

Ans: When the egg is not fertilized and the uterus has not received a fertilized egg, the lining becomes thick. The thick and soft inner lining of the uterus along with the blood vessels and the dead egg comes out of the vagina in the form of blood. This cycle is known as menstruation.

21. How will an organism be benefited if it reproduces through spores?

Ans: An organism is benefited if it reproduces through spores as spores are enclosed by thick walls that protect them until they come into contact with appropriate moist surface and can begin to grow.

22. How is the process of pollination different from fertilization?

Ans: Difference between pollination and fertilization is as follows:

22. What is the role of the seminal vesicles and the prostate gland?

Ans: Seminal vesicles and prostate gland secretions provide fluid medium to sperm, which makes the transport easy and also provide nutrition to sperms.

23. What are the changes seen in girls at the time of puberty?

Ans: During puberty in girls the shape of breast is changed. The breast size begins to increase with darkening of the skin of the nipples at the tip of breasts. Also, menstruation starts around this time.

24. If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?

Ans: Copper-T is used to prevent pregnancy. It cannot protect the woman from obtaining sexually transmitted diseases.

25. What are the advantages of sexual reproduction over asexual reproduction?

Ans: Sexual reproduction results in variation due to recombination of genetic material DNA. These differences are important for survival of species. On the contrary, asexual reproduction does not cause variations.

26. What are the functions performed by the testis in human beings?

Ans: In human beings testes produce male gametes sperm. Testes secrete male sex hormone testosterone which helps in regulation of spermatogenesis and also keeps structure and function of secondary sex types like facial, axial and public hair, voice moustache, etc.

27. How are the modes of reproduction different in unicellular and multicellular organisms?

Ans: In unicellular organisms formation of new individuals is done through the process of cell division or fusion. In multicellular organisms with simple body organization budding, fragmentation may work but in complex multicellular organisms only sexual reproduction takes place.

28. How does reproduction help in providing stability to populations of species?

Ans: To maintain the body design features the consistency of DNA copying during reproduction is important that allow the organism to use the particular function. Reproduction is, therefore, reproduction helps in providing stability to populations of species.

29. A couple wants to space the birth of their second child. Suggest one preventive method which could be observed

1.  By the husband

Ans: The preventive method used by the husband could be the use of condoms.

2.  By the wife for the same.

Ans: The preventive method used by the wife could be the use of oral pills or loop or Copper-T.

30. A girl attains her puberty at the age of 11 years and a boy at 13 years but, still they are asked to refrain from sex, why?

Ans: They are asked to refrain from sex because they are not mature enough to bear the responsibility of child. They may suffer from reproductive tract infections.

31. A pregnant woman visits a doctor to determine the sex of her child. The doctor refused to perform the test. Why is she being denied?

Ans: The sex determination is a crime in India. The doctor refused to perform the test in order to prevent female feticide which leads to shocking drop in child sex ratio.

32. Blueprints of body design are stored in the DNA. Why?

Ans: The chromosomes present within the nucleus of a cell contain information for inheritance of features from parents to child in the form of DNA molecules. DNA is the information basis for creating proteins. Thus, blueprints of the body design are stored in the DNA.

33. Protozoan reproduce by binary fission as well as by multiple fission. In your opinion which process is better and why? 

Ans: Multiple fission is better than binary fission because in multiple fission organisms divides into multiple individuals. It helps to tide over unfavorable conditions.

34. What causes joining up of stock and scion in the grafting technique of vegetative propagation in plants? Define the terms stock and scion. Name one positive trait each of the plant contributing scion and stock should have.

Ans: The combining of the vascular tissues of the scion and stock causes joining of the two parts in grafting technique of vegetative propagation in plants. The plant contributing root stock should be ready to keep the plant more immune to diseases and pests that are soil borne. The plant contributing scion should be ready to produce flowers and fruits quicker than those plants which are planted through seeds. Any desirable trait which is required in the offspring is the positive trait. For Example - large number of fruit production.

35. Why is it said that “sexual reproduction promotes diversity of characters in the offspring”?

Ans: Sexual reproduction promotes diversity because it results from the separation of two gametes from two different and sexually distinct individuals. This leads to variation, which is necessary for development.

36. Name the causative organism of syphilis and gonorrhea grafted on the other plant and it contributes the stem. The plant contributing scion should have large sized fruits and the plant contributing stock should have a deep root system.

Ans: The causative organism of syphilis is Treponema pallidum and causative organism of gonorrhea is Nisseria gonorrhoeae.

37. What happens if the fallopian tubes are partially blocked and the ovulated eggs are prevented from reaching the uterus?

Ans: If the fallopian tubes are partially blocked, fertilization may take place in the tube instead of the uterus.

38. Why is variation possible in the progeny of sexually reproductive individuals?

Ans: Variations are possible in the progeny of sexually reproductive individuals because the copy of DNA in newly formed cells is not like the copy DNA of the original cell.

Short Answer Questions (3 Marks)

1. What changes occur in girls and boys in the age group of 10 -14 years?

Ans: In the age group of 10-14 following changes occur in boys:

• Broadening of shoulder

• Deepening of voice

• Presence of beard and moustaches

• Development of sex organs

In the age group of 10-14 following changes occur in girls:

• Widening of pelvis and hips.

• High pitch voice.

• Growing axillary and pubic hair

• Initiation of menstrual cycle.

• Growth of mammary glands.

2. Describe sexually transmitted diseases (STDs) and mention the ways to prevent them.

Ans: Infective diseases which are spread by sexual contact called sexually transmitted diseases (STDs).

STDs can be preventing by the following ways:

• People should be aware about sexually transmitted diseases.

• Extra – marital relations should be avoided

• Sex without proper precaution should be avoided

• High standard of moral education should be given to the people.

3. Name the surgical methods of birth control in human males and females respectively.

Ans: Surgical methods of birth control in male are Castration and Vasectomy. In castration testes are removed from the body of a male. In vasectomy small pieces of both the vas deferens are cut and removed.

Surgical methods of birth control in females are ovariectomy, tubectomy and laparoscopy. In ovariectomy, ovaries are removed from the body. In tubectomy small pieces of both the fallopian tubes are removed and in laparoscopy fallopian tubes are blocked with the help of an instrument named laparoscope.

4. What are the essential requisites for sexual reproduction?

Ans: Essential requisites for sexual reproduction are transfer of germ cells either by external release of germ cells or by internal transfer of germ cells. Another requirement is special organs like an erectile organ called penis and organs which can carry the baby for a long period.

5. What is micropropagation? Mention its advantages.

Ans: Micropropagation is a type of artificial vegetative propagation in which an isolated plant part is cultivated under germ-free conditions with proper nutrient medium. 

Advantages of micro-propagation are as follows:

• It is a fast method to get multiple plants.

• Germ free plants are produced by this method from virus infected plants.

• It can overcome seed dormancy.

6. Mention the events taking place when the ovum is fertilized in the fallopian tube till it is implanted in the uterus of a human female.

Ans: When the ovum is fertilized, it starts dividing in the form of a ball or cells or also known as embryo. After 4-5 days the zygote becomes a multicellular structure blastocyst. The blastocyst gets attached to the lining of the uterus during implantation.

7. What are the post-fertilization changes in the flower?

Ans: After fertilization, the egg divides to form an embryo in the ovule. The ovule grows a coat and is gradually converted into a seed. The ovaries grow rapidly and ripen to form a fruit. The sepals, petals and stamens wither off, style and stigma degenerate. The seed contains the embryo which germinates to produce a new plant.

8. What are the major factors responsible for population explosion?

Ans: The major factors responsible for population explosion are as follows:

• Improved medical facilities have resulted in a fall of death rate.

• People are not well educated and not aware about family planning.

• Some people think that family planning is against the norms set by their religion.

• Early marriage is also a reason for population explosion.

• There is a lot of improvement in sanitary conditions which led to an increase in population.

9. What are the advantages of vegetative propagation?

Ans: Advantages of vegetative propagation are as follows:

• It is a speedy, inexpensive and easy method of reproduction of multiple numbers of plants.

• Plants produced are genetically identical plants (clones) that have similar characteristics to the parent.

• Plants rose by vegetative propagation earlier produce fruits and flowers and have superior quality fruits or flowers.

• Disease free plants can be produced by vegetative propagation.

10.Describe any 3 methods of asexual reproduction

Ans: Three methods of asexual reproduction are primary fission, spore formation and fragmentation.

• Primary fission – in primary fission organisms divides into two or multiple cells to produce new individuals. In a unicellular organism, the organism divides into two equal halves. In a multicellular nucleus, division first and then division of cytoplasm takes place.

• Spore formation – A spore may be a small microscopic structure with a thick wall. Spores are formed during a structure called sporangium. Nucleus inside the sporangium divides repeatedly and produces many nuclei. Each nucleus is surrounded by cytoplasm and called spore.

• Fragmentation – Multi-cellular organisms with simple body structure simply break into two or more parts upon maturation. This part or fragment grows to form a new individual.

11. What changes occur in ovaries during the menstrual cycle?

Ans: Change occurs in ovaries during menstruation cycle are-

• 1 – 4 days – The ovary starts preparing for the maturation of a new follicle.

• 5 – 13 days – Ovarian follicle develops to optimum. Estrogen secreted by ovaries causes thickening of the uterine wall.

• 14 day – Egg gets released from the ovary. It enters the fallopian tube, known as ovulation.

• 15 to 28 days – After releasing the egg, the follicle part produces corpus luteum which produces progesterone. If the egg is not fertilized the lining of the uterus slowly breaks and comes out through the vagina in the form of blood.

12. Describe budding in yeast, a fungus.

Ans: Organism such as yeast use asexual reproduction process known as budding to reproduce new cells. In this process a bud develops as an outgrowth on the parent organism due to single cell division. The bud gradually grows in size and gets detached from the parent when fully matured and develops into an adult organism, similar to the parent.

13. What is the importance of reproduction?

Ans: Importance of reproduction are-

• To maintain the existence – Due to reproduction organisms are able to maintain their existence on the earth since their origin, million years ago.

• To preserve the species – Due to reproduction species (a group of similar organisms) are preserved as reproducing organisms produce new individuals which are very similar to themselves.

• Role in evolution – some variations are produced in the new organisms during reproduction which play an important role in evolution.

14. How are spores produced in sporangia of Rhizopus?

Ans: Spores are thread-like structures that developed above the hyphae of the bread mould (Rhizopus). The tiny blob-on-a-stick structures known as sporangia contain cells, or spores, that can eventually develop into new Rhizopus individuals. In each sporangium, a nucleus divides a number of times generating a large number of nuclei.

Nuclei surrounded by a little cytoplasm are covered by thick walls that protect them until they come into contact with another moist surface and can begin to grow. The wall of sporangium breaks to release the spores in air.

(Image will be uploaded soon)

15. Diagrammatically represent binary fission in amoeba.

Ans: Diagrammatic representation of binary fission in amoeba is as follows:

Cell division in amoeba is as follows:

(Image will be uploaded soon)

16. Draw a flow chart showing various types of reproduction with examples.

Ans: Flow chart showing various types of reproduction with example is as follows:

(Image will be uploaded soon)

17. What is grafting? Why is it used in horticulture practices?

Ans: Grafting is a method in which a plant stem is attached to another rooted plant. The cutting of the stem which is grafted on the other plant is scion and the rooted plant on which the cutting is grafted is called stock. The scion and stock are placed on each other such that there is no gap between them. The cambium action takes place between them and they get merged. Grafting is used in plants such as banana, orange, rose and jasmine because they lose the capacity to produce seeds.

18. What are the different methods of contraception?

Ans: Different methods of contraception are barrier method, chemical method and intrauterine contraceptive device method.

• Barrier method – In this method, a device used to stop the entry of sperms in the female genital tract. Condoms, Diaphragm, Cervical caps are used in this method.

• Chemical method – In this method certain drugs (containing hormones) are used by the females. These drugs are available in the form of pills. There are two types of pills generally used for preventing pregnancies i.e oral pills and vaginal pills or creams.

• Intrauterine contraceptive devices (IUCD) – IUCD like copper – T are placed in the uterus to prevent implantation of the fertilized egg inside the uterus.

19. What is AIDS? Name its causal organism. Mention its symptoms.

Ans: AIDS is a sexually transmitted disease. AIDS is caused by HIV virus and can be transmitted through infected blood, semen or vaginal fluid. Its full form is acquired immune deficiency syndrome. It destroys the immune system of the body. Some common symptoms of AIDS are fever, sore throat, weight loss, fatigue. Also the body can be attacked by other diseases like pneumonia, TB and certain cancers.

20. Explain vegetative reproduction through layering. Give examples.

Ans: In the process of layering a stem attached to the parent plant buried in the soil to produce the root. This rooted branch is called a layer. Layer is then separated from the parent plant to grow as a new individual plant. Example of layering is the Jasmine plant.

21. What is the importance of DNA copying in reproduction?

Ans: DNA copying in reproduction is the basic event. DNA contains information for the inheritance of features from parents to children. DNA present in the nucleus of cells is the information source for creating protein. If information is changed, altered proteins will be made that lead to different body designs.

22. Why is variation beneficial to the species but not necessarily for the individual?

Ans: Variations are useful for the existence of species in different environment conditions. If a population of reproducing organisms were suited to a specific niche and if the niche is drastically altered the population might be exhausted. However, some differences are present and some species will survive. Thus, variation is beneficial to species but not for the individual.

23. How does binary fission differ from multiple fissions?

Ans: The difference between binary fission and multiple fission is as follows:

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

Ans: Simple stricter organisms cut into a number of pieces and each piece grows as an individual. The reason is that complex organisms are not merely random collections of cells. Specialized cells are organized in them as tissues are organized in organs.  These organs have to be placed at definite positions in the body. So, regeneration is not possible in multicellular organisms.

25. Why is vegetative propagation practiced for growing some types of plants?

Ans: Plants produced by vegetative propagation are genetically identical plants that have similar characteristics to the parent. It is a speedy, inexpensive and easy method of reproduction of multiple numbers of plants. Plants rose by vegetative propagation earlier produce fruits and flowers than those produced by seeds. Disease free plants can be produced by vegetative propagation. Plants such as banana, orange, rose and jasmine are produced by vegetative propagation because they lose the capacity to produce seeds.

26. Why is DNA copying an essential part of the process of reproduction?

Ans: DNA copying in reproduction is the basic event. DNA contains information for the inheritance of features from parents to children. DNA present in the nucleus of cells is the information source for creating protein. If information is changed, altered proteins will be made that lead to different body designs.

27. How does the embryo get nourishment inside the mother’s body?

Ans: A special disc-like structure is made between the embryo and the uterus wall called placenta. It is a link between the mother and the foetus. The embryo gets nutrition from the mother’s body with the help of placenta. This disc remains embedded within the uterine wall and has villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi. This provides an outsized area for glucose and oxygen to transfer the mother to the embryo and waste products from embryo to mother.

28. Why does menstruation occur?

Ans: If the egg is not fertilized it remains for one day. If the ovary does not get fertilized, its lining becomes thick and spongy. Now, as fertilization doesn’t occur this lining is not needed. The lining breaks slowly and comes out through the vagina in the form of blood. This cycle takes place every month and is known as menstruation.

29. Draw a labeled diagram of the longitudinal section of a flower.

Ans: The labelled diagram of the longitudinal section of flower is as follows:

(Image will be uploaded soon)

30. What are the different methods of contraception?

Ans: Different methods of contraception are barrier method, chemical method and surgical method.

• Barrier method – In this method, a device used to stop the entry of sperms in the female genital tract. Condom, Diaphragm, Cervical caps and Copper-T are used in this method.

• Chemical method – In this method certain drugs (containing hormones) are used by the females. These drugs are available in the form of pills. There are two types of pills generally used for preventing pregnancies i.e oral pills and vaginal pills or creams.

• Surgical method – In this method small part of vas deferens in male is cut and removed. It is known as vasectomy. In females the oviduct of the female is removed, it is known as tubectomy.

31. What could be the reasons for adopting contraceptive methods?

Ans: The sexual action always leads to pregnancy. If a woman is not physically and mentally ready to have a child, contraceptive methods are used to avoid pregnancy. Many diseases can be transmitted sexually. Some contraceptive methods like condoms also prevent spread of STDs and dangerous diseases like HIV-AIDS.

32. Producing individuals by parents consumes a lot of energy. So, why should an individual organism waste energy in the process, it does not need to stay alive?

Ans: Reproduction is necessary to maintain the balance in nature. Reproduction provides stability to the population of species so unlike other life processes it is not essential to take care of the lifetime of an individual organism. 

33. Blueprints of body design are stored in the DNA. Why?

Ans: The chromosomes present within the nucleus of a cell contain information for inheritance of features from parents to child in the form of DNA molecules. DNA is the information basis for creating proteins. Thus, blueprints of the body design are stored in the DNA.

34. Why is variation beneficial to the species but not necessary for the individual?

Ans: Variations are useful for the existence of species in different environment conditions. If a population of reproducing organisms were suited to a specific niche and if the niche is drastically altered the population might be exhausted. However, some differences are present and some species will survive. Thus, variation is beneficial to species but not for the individual.

35. What is the advantage of reproduction through spores in the case of Rhizopus?

Ans: The advantage of reproduction through spores in Rhizopus is that spores are enclosed by thick walls that protect them until they come into contact with an appropriate moist surface and can begin to grow.

Long Answer Questions (5 Marks)

1. Describe triple fusion in plants? Where does it occur? Draw a neat and clean well labeled diagram to support your answer.

Ans: After pollination, the pollen grains germinate within the stigma by producing plant parts. This plant part is made from the inner wall of the pollen grain. It penetrates the stigma and passes through the design and enters the ovule through a gap called male gamete it releases two male gametes within the embryo sac. One male gamete fuses with egg cells and second fuses with two polar nuclei. The fusion of 1 male gamete with the egg cells is named syngamy. The fusion of the second male gamete with two polar nuclei is called triple fusion. This process occurs in the ovary.

The labelled diagram is as follows:

2. Draw a well labelled diagram of the female reproductive system and mention its parts.

Ans: A labelled diagram of the female reproductive system is as follows:

(Image will be uploaded soon)

Various parts of the female reproductive system are as follows:

• A pair of ovaries – ovaries produces egg and female sex hormones. One egg is produced every month by one of the ovaries. 

• Fallopian tubes – There are two fallopian tubes. It carries eggs from the ovary to the womb. Fertilization happens in fallopian tubes.

• Uterus – It is a pear-shaped hollow muscular structure. The fertilized egg remains attached to the uterus wall.

• Vagina – It is a thin muscular tube. Its upper end is connected to the cervix of the uterus and the lower end opens outside through an opening. It is a place for copulation.

3. Draw a well labeled diagram of male reproductive system and describe its parts.

Ans: Labeled diagram of male reproductive system is as follows:

Various parts of a male reproductive system are as follows:

• A pair of testes – Testes secretes male sex hormone testosterone which helps in regulation of spermatogenesis and also keeps structure and function of secondary sex types like facial, axial and public hair, voice moustache, etc. Tests are present in a small pouch called scrotum. 

• Epididymis – It is a long spiral tube. The head is linked with testis and tail is linked with vas deferens.

• Vas deferens – It is a long tube which begins from the tail of epididymis. The sperms formed are transported through vas deferens.

• Urethra – It receives the vas deferens from both the testes. It opens outside through penis. It carries both sperms and urine.

• Prostate gland – Prostate gland secretions provide fluid medium to sperm, which makes the transport easy and also provide nutrition to sperms.

4. Differentiate between asexual and sexual reproduction.

Ans: Difference between asexual and sexual reproduction is as follows:

5. What is the need of population control?

Ans: Expanding population leads to number of problems like –

• Unemployment – More population requires more jobs and if enough employment is not available, it leads to unemployment.

• Living standard – Population explosion makes it tougher to improve the living standard.

• Poverty – If there are more people in the family and the income is less, it develops poverty with the addition of every child.

• Food supply – If the population increases and the food production does not increase; this will lead to shortage of food supply.

• Hygienic condition – Additional people in small areas usually make the condition unhygienic for survival.

• Educational problem – In a family if there are more children, it becomes difficult to provide education to all with limited income.

• Pollution – More pollution with increasing population.

• Decrease in natural resources – More people will consume more natural resources, it decreases the natural resources quickly.

What are the Benefits of Important Questions from Vedantu for Class 10 Science Chapter 8 - How Do Organisms Reproduce

• Focus on key topics for efficient studying.

• Prepares students for exams and reduces anxiety.

• Reinforces understanding of fundamental concepts.

• Teaches effective time management.

• Enables self-assessment and progress tracking.

• Strategic approach for higher scores.

• Covers a wide range of topics for comprehensive understanding.

• Supports exam preparation and boosts confidence.

Important Related Links for CBSE Class 10 Science