SCIENCE CLASS 8 CHAPTER 9 REPRODUCTION IN ANIMALS
NCERT Class 8 Science – Chapter 9: Reproduction in Animals
Important Questions and Answers
A. Very Short Answer Questions
Q1. What is reproduction?
Answer: Reproduction is the biological process by which living organisms produce offspring of their own kind.
Q2. What are the two main types of reproduction?
Answer: The two main types of reproduction are:
Sexual reproduction
Asexual reproduction
Q3. What is sexual reproduction?
Answer: Sexual reproduction is a type of reproduction in which male and female reproductive cells fuse to form a new organism.
Q4. What are gametes?
Answer: Gametes are reproductive cells. The male gamete is called the sperm, and the female gamete is called the ovum or egg.
Q5. What is fertilisation?
Answer: Fertilisation is the fusion of a male gamete and a female gamete to form a zygote.
Q6. What is a zygote?
Answer: A zygote is the single cell formed by the fusion of a sperm and an ovum.
Q7. What is an embryo?
Answer: An embryo is the early developing stage of an organism formed from the zygote.
Q8. What is a foetus?
Answer: A foetus is a later stage of development in which the developing baby has recognisable body parts.
Q9. What is internal fertilisation?
Answer: Internal fertilisation is the fusion of male and female gametes inside the female's body.
Q10. What is external fertilisation?
Answer: External fertilisation is the fusion of male and female gametes outside the female's body, usually in water.
B. Short Answer Questions
Q11. Why is reproduction important for living organisms?
Answer: Reproduction is important because it produces new individuals and helps maintain the continuity of a species from one generation to the next.
Q12. Differentiate between sexual and asexual reproduction.
Answer:
Sexual Reproduction | Asexual Reproduction |
|---|---|
Usually involves male and female gametes. | Does not involve the fusion of gametes. |
Fertilisation occurs. | Fertilisation does not occur. |
Offspring often show variations. | Offspring are generally very similar to the parent. |
Example: humans and frogs. | Example: Amoeba and Hydra. |
Q13. What is the difference between internal and external fertilisation?
Answer:
Internal Fertilisation | External Fertilisation |
|---|---|
Occurs inside the female's body. | Occurs outside the female's body. |
Example: humans, cows and dogs. | Example: many fish and frogs. |
The gametes are brought together inside the body. | The gametes are usually released into water. |
Q14. Name the male reproductive organs in humans.
Answer: The main male reproductive organs are:
A pair of testes
Two sperm ducts
Urethra
Penis
The testes produce sperms and the male sex hormone testosterone.
Q15. Name the female reproductive organs in humans.
Answer: The main female reproductive organs are:
A pair of ovaries
Two oviducts (fallopian tubes)
Uterus
Vagina
The ovaries produce ova and female sex hormones.
Q16. What is the function of the testes?
Answer: The testes produce male gametes called sperms and secrete the hormone testosterone.
Q17. What is the function of the ovaries?
Answer: The ovaries produce female gametes called ova or eggs and secrete female sex hormones.
Q18. What happens after fertilisation?
Answer: After fertilisation, a zygote is formed. It divides repeatedly to form a group of cells, which develops into an embryo. In humans, the embryo implants in the uterus and continues to develop.
Q19. What is metamorphosis? Give an example.
Answer: Metamorphosis is the process in which an animal undergoes major changes in body form during its development. For example, a tadpole develops into an adult frog.
Q20. What is cloning?
Answer: Cloning is the process of producing a genetically identical copy of a cell or organism. Dolly the sheep was a famous example of a cloned mammal.
C. Long Answer Questions
Q21. Explain the process of reproduction in humans.
Answer: Humans reproduce through sexual reproduction.
The male reproductive system produces sperms in the testes.
The female reproductive system produces ova in the ovaries.
During fertilisation, a sperm fuses with an ovum, usually in an oviduct.
The fusion forms a zygote.
The zygote divides repeatedly and develops into an embryo.
The embryo attaches to the wall of the uterus.
As development continues, it becomes a foetus.
After approximately nine months of pregnancy, the baby is usually born.
Q22. Explain the stages of development from a zygote to a baby.
Answer:
The major stages are:
Zygote: Formed by the fusion of sperm and ovum.
Cell division: The zygote divides repeatedly to produce more cells.
Embryo: The developing organism reaches an early stage in which body structures begin to form.
Implantation: In humans, the embryo attaches to the lining of the uterus.
Foetus: The developing baby grows and its body parts become recognisable.
Birth: After the pregnancy period, the baby is born.
Q23. Explain asexual reproduction in Amoeba and Hydra.
Answer:
Asexual reproduction in Amoeba — Binary fission
The nucleus divides into two nuclei.
The cytoplasm divides.
Two daughter Amoebae are formed from one parent.
Asexual reproduction in Hydra — Budding
A small outgrowth called a bud develops on the parent's body.
The bud grows through repeated cell division.
It develops into a young Hydra.
The young Hydra separates from the parent and lives independently.
Q24. Explain the difference between an embryo and a foetus.
Answer:
An embryo is an early stage of development after the zygote begins dividing. During this stage, basic body structures start to form.
A foetus is a later developmental stage in which the major body parts can be recognised. It continues to grow and mature until birth.
Q25. Describe the process of fertilisation in frogs.
Answer:
A female frog lays eggs in water.
The male frog releases sperms over the eggs.
The sperm and egg fuse outside the female's body.
Fertilisation produces zygotes.
The zygotes develop into embryos and then tadpoles.
The tadpoles undergo metamorphosis and develop into adult frogs.
D. Fill in the Blanks
The process by which organisms produce offspring is called reproduction.
The male gamete in humans is called a sperm.
The female gamete is called an ovum.
The fusion of male and female gametes is called fertilisation.
The cell formed after fertilisation is called a zygote.
In humans, the embryo develops in the uterus.
Amoeba reproduces by binary fission.
Hydra reproduces asexually by budding.
The transformation of a tadpole into an adult frog is called metamorphosis.
Dolly was a famous cloned sheep.
E. True or False
Reproduction helps maintain the continuity of a species. — True
Fertilisation is the fusion of male and female gametes. — True
The testes produce ova. — False
The ovaries produce ova. — True
External fertilisation usually occurs inside the female's body. — False
Amoeba reproduces by binary fission. — True
Hydra can reproduce by budding. — True
A zygote is formed before fertilisation. — False
Frogs undergo metamorphosis. — True
Sexual reproduction always produces offspring genetically identical to the parent. — False
F. Important Diagram-Based Questions
Practise drawing and labelling these diagrams for examinations:
Male reproductive system in humans.
Female reproductive system in humans.
Binary fission in Amoeba.
Budding in Hydra.
Different stages in the development of a frog.
Development of a human embryo.
G. Important Questions for Revision
Define reproduction and explain its importance.
What is fertilisation? Explain its two types.
Differentiate between sexual and asexual reproduction.
Describe the male and female reproductive systems in humans.
Explain the development of a zygote into an embryo.
What is metamorphosis? Explain with an example.
Explain binary fission in Amoeba.
Explain budding in Hydra.
What is cloning? Name the famous cloned sheep.
Differentiate between an embryo and a foetus.
Crop Production And Management
Microorganisms - Friend And Foe
Synthetic Fibre And Plastic
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