Chapter 9: Reproduction in Animals  

Extra Inmternal Question and Answer :

Question: What is reproduction? What are the two main types of reproduction?

Answer: Reproduction is the process by which living organisms produce new individuals of their own kind. It helps in the continuation of a species.

The two main types of reproduction are:

(i) Asexual reproduction

(ii) Sexual reproduction

Question: Why is reproduction important for living organisms?

Answer: Reproduction is important for living organisms because it helps in producing new individuals of the same kind. It ensures the continuation of a species and prevents its extinction. It also maintains the balance of population in nature.

Question: Define asexual reproduction with example

Answer: Asexual reproduction is a type of reproduction in which a single parent is involved and no fusion of gametes takes place. The offspring produced are almost identical to the parent. For example, Amoeba reproduces by binary fission.

Question: Define sexual reproduction with example.

Answer: Sexual reproduction is the process in which a new organism is produced by the fusion of male and female gametes. The male gamete (sperm) and female gamete (egg) combine to form a zygote, which develops into a new individual. Example: Humans reproduce by sexual reproduction.

Question: What is a gamete?

Answer: A gamete is a special reproductive cell involved in sexual reproduction. The male gamete is called sperm and the female gamete is called egg (ovum). Gametes fuse during fertilisation to form a zygote.

Question: What is a zygote?

Answer: A zygote is the single cell formed when the male gamete (sperm) fuses with the female gamete (egg) during fertilisation.

Question: Where does internal fertilisation occur?

Answer: Internal fertilisation occurs inside the female body, where the sperm and egg fuse together in the reproductive system.

Question: Where does external fertilisation occur?

Answer: External fertilisation occurs outside the body of the female, where the fusion of male and female gametes takes place.

Question: What is binary fission? Give an example.

Answer: Binary fission is a method of asexual reproduction in which a single organism divides into two identical daughter cells. In this process, the parent cell splits and each new cell can grow into a complete organism. For example, Amoeba reproduces by binary fission.

Question: What is budding? Give an example.

Answer: Budding is a type of asexual reproduction in which a new organism develops from a small outgrowth called a bud on the parent body. The bud grows and then separates to form a new individual. Example: Hydra.

Question: What are viviparous animals? Give examples.

Answer: Viviparous animals are those animals which give birth to young ones. In these animals, the embryo develops inside the mother’s body. Examples: Human beings, cows and dogs.

Question: What are oviparous animals? Give examples.

Answer: Oviparous animals are those animals which lay eggs outside their body. The development of the embryo takes place inside the egg after it is laid. Examples: Frog, fish, hen, and crow.

Question: Differentiate between viviparous and oviparous animals.

Answer: The difference between viviparous and oviparous animals is :

viviparous	oviparous
Give birth to young ones.	Lay eggs.
Embryo develops inside the mother’s body.	Embryo develops inside the egg outside the mother’s body.
Young ones are more protected before birth.	Eggs are usually less protected.
Example: human beings, cows.	Example: hen, frog.

Question: Draw the labelled diagram of male reproductive organs in humans.

Answer: The diagram of male reproductive organs in humans.

Question: Draw the labelled diagram of female reproductive organs in humans.

Answer: The diagram of female reproductive organs in humans.

Exercises

1. Explain the importance of reproduction in organisms.

Answer: Reproduction is important for living organisms because it helps in the continuation of their species. Without reproduction, all organisms would eventually die out and life on Earth would not continue. It also helps in transferring characters from parents to their young ones. In some cases, reproduction leads to variations, which help organisms to adapt and survive better in changing environmental conditions.

2. Describe the process of fertilisation in human beings.

Answer: Fertilisation in human beings is the process in which the male gamete (sperm) fuses with the female gamete (egg). This usually takes place in the oviduct (fallopian tube). During this process, the nuclei of sperm and egg combine to form a single cell called a zygote. The zygote then begins to divide and develops into an embryo.

3. Choose the most appropriate answer.
(a) Internal fertilisation occurs
(i) in female body.
(ii) outside female body.
(iii) in male body.
(iv) outside male body.

Answer: (i) in female body.

[ Internal fertilisation happens when the sperm meets and fuses with the egg inside the female reproductive system.]

(b) A tadpole develops into an adult frog by the process of
(i) fertilisation (ii) metamorphosis (iii) embedding (iv) budding

Answer: (ii) metamorphosis

[ A tadpole changes into an adult frog through metamorphosis, where its body structure gradually transforms into the adult form.]

(c) The number of nuclei present in a zygote is
(i) none (ii) one (iii) two (iv) four

Answer: (ii) one

[ After fertilisation, the nuclei of sperm and egg fuse together, forming a single nucleus in the zygote.]

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 fertilisation takes place in frog. ( )
(d) A new human individual develops from a cell called gamete. ( )
(e) Egg laid after fertilisation is made up of a single cell. ( )
(f) Amoeba reproduces by budding. ( )
(g) Fertilisation is necessary even in asexual reproduction. ( )
(h) Binary fission is a method of asexual reproduction. ( )
(i) A zygote is formed as a result of fertilisation. ( )
(j) An embryo is made up of a single cell. ( )

Answer: (a) Oviparous animals give birth to young ones.-- False (F)
(b) Each sperm is a single cell. -- True (T)
(c) External fertilisation takes place in frog. --  True (T)
(d) A new human individual develops from a cell called gamete. -- False (F)
(e) Egg laid after fertilisation is made up of a single cell. --  True (T)
(f) Amoeba reproduces by budding. --  False (F)
(g) Fertilisation is necessary even in asexual reproduction. --  False (F)
(h) Binary fission is a method of asexual reproduction. -- True (T)
(i) A zygote is formed as a result of fertilisation. -- True (T)
(j) An embryo is made up of a single cell. -- False (F)

5. Give two differences between a zygote and a foetus.

Answer: The two differences between a zygote and a fetus is:

Zygote	Foetus
It is the first single cell formed after fertilisation.	It is the stage when the embryo develops body parts.
It is very small and keeps dividing to form an embryo.	It is more developed and shows recognisable body features.

6. Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Answer: Asexual reproduction is the type of reproduction in which a single parent is involved, and no fusion of gametes takes place. The new organism is identical to the parent.

Two methods of asexual reproduction in animals are:

(i) Binary fission: In this process, a single organism splits into two identical daughter organisms. Example: Amoeba.

(ii) Budding: In this method, a small outgrowth (bud) develops on the parent body and grows into a new individual. Example: Hydra.

7. In which female reproductive organ does the embryo get embedded?

Answer: The embryo gets embedded in the uterus (womb) of the female reproductive system.

8. What is metamorphosis? Give examples.

Answer: The transformation of the larva into an adult through drastic changes is called metamorphosis.

Examples: Frog (tadpole to adult frog) and silkworm (larva to adult moth).

9. Differentiate between internal fertilisation and external fertilisation.

Answer: The difference between internal fertilisation and external fertilization :

Internal fertilisation	External fertilisation
Fusion of male and female gametes takes place inside the female body.	Fusion of male and female gametes takes place outside the female body, usually in water.
Occurs in animals like humans, cows and dogs.	Occurs in animals like frogs and fish.
Fewer eggs are produced.	Large number of eggs are produced.
Protection of developing embryo is better.	Less protection, so many eggs or embryos may not survive.

10. Complete the crossword puzzle using the hints given below.

          Across
1. The process of the fusion of the gametes.
6. The type of fertilisation in hen.
7. The term used for bulges observed on the sides of the body of hydra.
8. Eggs are produced here.
          Down
2. Sperms are produced in these male reproductive organs.
3. Another term for in vitro fertilisation.
4. These animals lay eggs.
5. A type of fission in amoeba.

Answer:   Across
1. The process of the fusion of the gametes.---- Fertilisation .
6. The type of fertilisation in hen. ---- Internal
7. The term used for bulges observed on the sides of the body of hydra. ---- buds
8. Eggs are produced here. ---- Ovary
          Down
2. Sperms are produced in these male reproductive organs. ---- Testes
3. Another term for in vitro fertilisation. ---- IVF
4. These animals lay eggs.---- Oviparous .
5. A type of fission in amoeba.---- Binary .