CBSE Class 8 Science Chapter 9: Reproduction in Animals NCERT Solutions

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NCERT Solutions PDF Class 8 PDF

This chapter delves into the fascinating process of reproduction in animals, a fundamental biological concept for Class 8 Science students. The NCERT Solutions for Chapter 9, 'Reproduction in Animals,' provide clear explanations and step-by-step answers to textbook exercises. Key topics covered include the importance of reproduction for species continuation, the distinction between sexual and asexual reproduction, and detailed descriptions of fertilization, both internal and external. Students will learn about the development of embryos, the processes of metamorphosis in amphibians, and the differences between a zygote and a foetus. These solutions are designed to help students understand complex biological processes, clarify doubts, and prepare effectively for their examinations by offering accurate and easy-to-understand explanations for each question.

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BoardCBSE
ClassClass 8
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 9: Reproduction in Animals

Chapter summary

Chapter 9, 'Reproduction in Animals,' focuses on the biological mechanisms that ensure the continuation of species. This NCERT Solutions set covers the importance of reproduction, differentiating between sexual and asexual modes. It explains fertilization, including internal and external types, and traces the development from zygote to embryo and foetus. Key processes like metamorphosis are also discussed. The solutions provide clear answers to exercise questions, aiding students in grasping these essential concepts for their Class 8 Science curriculum.

Learning outcomes

  • Understand the importance of reproduction for the survival of species.
  • Differentiate between sexual and asexual modes of reproduction.
  • Explain the process of fertilization in humans and other animals.
  • Describe the development of an embryo from a zygote.
  • Identify the stages of metamorphosis in animals like frogs.
  • Distinguish between a zygote and a foetus.

Topics covered

Paper topics

  • Importance of Reproduction
  • Sexual Reproduction
  • Asexual Reproduction
  • Male Reproductive Organs
  • Female Reproductive Organs
  • Sperms
  • Ova (Eggs)
  • Fertilization (Internal and External)
  • Zygote
  • Embryo
  • Foetus
  • Metamorphosis

Important topics

  • Sexual vs. Asexual Reproduction
  • Process of Fertilization
  • Zygote to Embryo Development
  • Metamorphosis
  • Internal vs. External Fertilization

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Questions and Solutions

Question 1

Explain the importance of reproduction in organisms.
Solution: Reproduction is a fundamental biological process that is crucial for the survival and continuation of all living organisms and species. Its primary importance lies in ensuring that life continues beyond the lifespan of an individual. Through reproduction, organisms create new individuals that are similar to themselves, thereby maintaining the existence of their species over time. Without reproduction, species would eventually die out as individuals age and perish.

Question 2

Describe the process of fertilization in human beings.
Solution: Fertilization in human beings is a part of sexual reproduction and occurs internally. The male reproductive system produces male gametes called sperms, while the female reproductive system produces female gametes called ova (or eggs). During sexual intercourse, millions of sperms are ejaculated into the female reproductive tract. If ovulation has occurred, one or more mature ova are present in the fallopian tube. The sperms travel towards the ovum, and typically, only one sperm successfully penetrates and fuses with the ovum. This fusion of the sperm nucleus with the ovum nucleus results in the formation of a single diploid cell called a zygote. This process is known as internal fertilization. The zygote then begins to divide and develop into an embryo, which implants in the wall of the uterus and continues to grow into a foetus.

Question 3

Choose the most appropriate answer:
  1. Internal fertilization occurs
    1. in female body.
    2. outside female body.
    3. in male body.
    4. outside male body.
  2. A tadpole develops into an adult frog by the process of
    1. fertilization.
    2. metamorphosis.
    3. budding.
    4. none.
  3. The number of nuclei present in a zygote is
    1. none.
    2. one.
    3. two.
    4. four.
Solution:
  1. Internal fertilization occurs (i) in female body. This is because the fusion of male and female gametes takes place within the reproductive tract of the female.
  2. A tadpole develops into an adult frog by the process of (ii) metamorphosis. This is a biological process involving distinct changes in the body structure from the larval stage (tadpole) to the adult stage (frog).
  3. The number of nuclei present in a zygote is (ii) one. A zygote is formed by the fusion of the nucleus of a sperm and the nucleus of an ovum, resulting in a single nucleus containing the combined genetic material.

Question 4

Indicate whether the following statements are True (T) or False (F):

(a) Oviparous animals give birth to young ones.

(b) Each sperm is a single cell.

(c) External fertilization takes place in frog.

(d) A new human individual develops from a cell called gamete.

(e) Egg laid after fertilization is made up of a single cell.

(f) Amoeba reproduces by budding.

(g) Fertilization is necessary even in asexual reproduction.

(h) Binary fission is a method of asexual reproduction.

(i) A zygote is formed as a result of fertilization.

(j) An embryo is made up of a single cell.

Solution:

(a) Oviparous animals give birth to young ones. (False) Oviparous animals lay eggs, while viviparous animals give birth to young ones.

(b) Each sperm is a single cell. (True) A sperm is the male gamete, which is a single, specialized cell.

(c) External fertilization takes place in frog. (True) Frogs typically reproduce through external fertilization, where eggs and sperm are released into water.

(d) A new human individual develops from a cell called gamete. (False) A new human individual develops from a zygote, which is formed by the fusion of two gametes (sperm and ovum).

(e) Egg laid after fertilization is made up of a single cell. (True) The fertilized egg, or zygote, is initially a single cell. In oviparous animals, this single-celled zygote develops within the egg laid by the mother.

(f) Amoeba reproduces by budding. (False) Amoeba primarily reproduces by binary fission, where the cell divides into two identical daughter cells. Budding is seen in organisms like Hydra.

(g) Fertilization is necessary even in asexual reproduction. (False) Fertilization is the fusion of gametes and is a key part of sexual reproduction. Asexual reproduction does not involve the fusion of gametes.

(h) Binary fission is a method of asexual reproduction. (True) Binary fission is a process where a single organism divides into two identical organisms, which is a form of asexual reproduction.

(i) A zygote is formed as a result of fertilization. (True) Fertilization is the process that leads to the formation of a zygote.

(j) An embryo is made up of a single cell. (False) An embryo is a multicellular organism that develops from a zygote through repeated cell division and differentiation.

Question 5

Give two differences between a zygote and a foetus.
Solution:

Here are two key differences between a zygote and a foetus:

  1. Cellularity: A zygote is a single-celled structure, formed immediately after the fusion of sperm and ovum. A foetus, on the other hand, is a multicellular stage of development that results from the repeated division and differentiation of the zygote and embryo.
  2. Development of Body Parts: In a zygote, well-defined body parts are absent as it is just a single cell. In contrast, a foetus is characterized by the development of distinct body parts, such as limbs, organs, and other features, which become increasingly identifiable as development progresses.

Common mistakes

  • Confusing gametes with zygotes or embryos.
  • Incorrectly identifying the location of internal fertilization.
  • Mistaking budding or binary fission for fertilization.
  • Confusing oviparous and viviparous animals.

Revision tips

  • Focus on understanding the key differences between sexual and asexual reproduction.
  • Draw diagrams to visualize the process of fertilization and embryo development.
  • Memorize the definitions and key characteristics of terms like zygote, embryo, and foetus.
  • Review the examples of internal and external fertilization provided in the solutions.

Practice MCQs

Q1. Which of the following is the primary reason for reproduction in organisms?

Q2. In human beings, fertilization typically occurs:

Q3. The process by which a tadpole transforms into an adult frog is called:

Q4. How many nuclei are present in a zygote?

Q5. Which type of animals lay eggs?

Frequently asked questions

What is the main purpose of reproduction in animals?

The main purpose of reproduction is to ensure the continuation of a species by producing new individuals of the same kind, generation after generation.

What is the difference between internal and external fertilization?

Internal fertilization occurs inside the female body, where the male gamete fuses with the female gamete. External fertilization occurs outside the body, typically in an aquatic environment.

What is a zygote?

A zygote is the initial single cell formed when a male gamete (sperm) fuses with a female gamete (ovum) during fertilization. It contains the complete genetic material from both parents.

How does a tadpole develop into a frog?

A tadpole develops into an adult frog through a process called metamorphosis, which involves significant changes in its body structure.

What is the difference between a zygote and a foetus?

A zygote is a single cell, while a foetus is a multicellular stage of development where distinct body parts begin to form and develop.

Are all animals that lay eggs viviparous?

No, animals that lay eggs are called oviparous. Viviparous animals give birth to live young ones.

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