NCERT Solutions for Class 10 Science Chapter 8

NCERT Solutions for Class 10 Science Chapter 8 – How Do Organisms Reproduce?, contains solutions to various questions in Exercises for Chapter 8. How Do Organisms Reproduce Class 10 NCERT Solutions have been explained in a simple and easy to understand manner. We are providing NCERT Solutions for Class 10 all subjects which can be accessed by clicking here.

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

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

NCERT Solutions for Class 10 Science Chapter 8 – How Do Organisms Reproduce?, Exercises includes all in text and exercise solved questions which helps you to understand the topic covered in Chapter 8 How Do Organisms Reproduce? Class 10, in a better manner to help you to score good marks in your examinations.

NCERT Solutions for Class 10 Science Chapter 8 – Intext Questions – Page 128

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

Answer:

DNA contains genetic information. This information is necessary for reproduction of same kind of species. Humans give birth to humans and other kinds of animals to their own types. In the absence of DNA copying, the offspring will not be able to inherit the characteristics of its parents and a completely new or different kind of species will be born.

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

Answer:

Variation is beneficial to the species to avoid extinction. A species having varying individuals can adapt to changes in its environment more easily and can live in diversified environments. If some of the individuals from the species could not adapt to the change and did not survive, the species can still thrive.

Intext Questions – Page 133

1. How does binary fission differ from multiple fission?

Answer:

When a single cell divides to form two cells, it is called binary fission. Organisms like bacteria and amoeba undergo binary fission to multiply.

When a single cell divides into multiple daughter cells at the same time, it is said to be going through multiple fission. Sporozoans undergo multiple fission.

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

Answer:

An organism that reproduces through spores can be benefited in a number of ways. One sporangium can produce a large number of spores at once. These spores can be distributed at different places and can survive extreme environments giving them a healthy chance of survival.

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

Answer:

Complex organisms have complex organ systems. There are several levels of organs with their specific functions. These organs should be highly coordinated and controlled and require a multilevel management for the healthy survival of the organism.

It is not possible to regenerate such complex structures. Hence, complex organisms can not give rise to new individuals through regeneration.




4. Why is vegetative propagation practised for growing some types of plants?

Answer:

Vegetative propagation has many advantages. Many plants such as bananas and oranges are not easy to plant because of the nature of their seeds. In that case, vegetative propagation proves to be beneficial. This process can also be used where germination fails and plants are difficult to grow. It results in rapid and quality growth of plants, and is a cheap method to obtain a variety in the species.

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

Answer:

DNA copying helps in reproducing the same kind of offspring. In this process, the cell replicates the DNA and makes its copies. These copies carry genetic information from parent to progeny and helps structure the physiology of the offspring.

Intext Questions – Page 140

1. How is the process of pollination different from fertilisation?

Answer:

Pollination is the transfer of pollen from the male organ of the flower (anther) to the female organ of the flower (stigma). It can occur between two flowers or the same flower.

Fertilization occurs after pollination when the male and female gametes fuse to form a zygote.

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

Answer:

The role of seminal vesicles and the prostrate gland is to give a fluid medium for easy transportation of sperms to take place. It also aids the lubrication of sperms and provides nutrients like calcium, fructose, and enzymes.

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

Answer:

The following changes can be seen in girls at the time of puberty:

  • Beginning of menstrual cycle.
  • Increase in size of the uterus and ovaries.
  • Development of breasts and darkening of nipples.
  • Fat depositions around thighs and hips.
  • Hair growth on various body parts.
  • Frequent occurrence of pimples due to change in hormones.

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

Answer:

After fertilization, the line of the uterus thickens. The fertilised egg is attached to the uterine wall at a place called placenta. The blood flow in the uterus is abundant to nourish the embryo. Placenta has bristles like structures called villi that are attached to the embryo. Through this, the embryo is noursihed from the nutrients provided by mother’s blood and also gets rid of the waste products produced.




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

Answer:

No, using a copper – T can only help in birth control. It does not provide any protection against the exchange of body fluids. Hence, it will not help in protection against sexually transmitted diseases.

NCERT Solutions for Class 10 Science Chapter 8 – NCERT Exercise – Page 141

1. Asexual reproduction takes place through budding in

(a) amoeba

(b) yeast

(c) plasmodium

(d) leishmania

Answer:

(b) yeast

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

Answer:

(c) Vas deferens

3. The anther contains

(a) sepals

(b) ovules

(c) pistil

(d) pollen grains.

Answer:

(a) Pollen grains

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

Answer:

In sexual reproduction, the offspring derives genes from two parents, giving it characteristics of both the parents. Since two different set of genes is involved, a lot variation can be seen and the survival of the species is ensured as adaptation to the environment as per requirement is easier.

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

Answer:

Testis has the following functions in humans:

(i) Production of sperms.
(ii) Production of the hormones androgen and testosterone.

6. Why does menstruation occur?

Answer:

Every month, the wall of the uterus is prepared for a fertilized egg by providing sufficient blood for the nourishment of the embryo. The lining of the uterus thickens and waits for the fertilization to occur. When the released egg is not fertilized, the lining of the uterus breaks down resulting in bleeding called menstruation.

7. Draw a labelled diagram of the longitudinal section of a flower.

Answer:

Given below is a diagram of the longitudinal section of the flower.

flower

8. What are the different methods of contraception?

Answer:

There are following methods of contraception:

  1. Natural: In this method, mating is avoided between 10th and 17th day of the menstrual cycle as the chances of conceiving are the highest. This is not an effective way of contraception.
  2. Oral/chemical Contraceptives: This method includes ingestion or introduction of small portion of hormones in the form of pills or injections. These hormones block the eggs to avoid fertilization.
  3. Barrier Method: This method prohibits meeting of sperms and egg by providing a barrier between them. Condoms available for both male and female, diaphragms for female, cervical cap and contraceptive sponge for females are examples of this kind of contraception.
  4. Surgical methods/Implants: In these methods, implants like copper-T are placed in a woman’s body, or surgeries such as, the fallopian tubes are blocked in females to stop flow of eggs or vas deference is blocked in men to stop the flow sperms, are done.




9. How are the modes for reproduction different in unicellular and multicellular organisms?

Answer:

In unicellular organisms, the cell undergoes fission or budding in order to produce daughter cells.

Multicellular organisms have dedicated set of organs for reproduction. They can reproduce by spore formation, vegetative propagation, or other forms of sexual or asexual reproduction.

Complex multicellular organisms like humans and some other animals reproduce sexually.

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

Answer:

To avoid extinction of any species, reproduction is very important. Reproduction helps in producing more same type of species giving it a stable population and necessary community to survive.

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

Answer:

Adopting contraceptive methods is extremely important to avoid sexually transmitted diseases like aids and syphilis. It helps in avoiding unwanted pregnancies and also contributes in population control.

Topics Covered in How Do Organisms Reproduce Class 10 Science

  • Do Organisms create exact copies of themselves?
  • Modes of Reproduction Used by Single organisms
  • Sexual Reproduction
    • Reproduction in Human Beings
      • Male Reproductive System
      • Female Reproductive System
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