Lesson: Reproduction in Animals
Exercise:

Question: 1

Explain the importance of reproduction in organisms.

Solution:

Reproduction ensures the continuation of species, generation after generation, by helping the organisms to produce their offspring.  If reproduction does not take place, no organisms will survive and all life would become extinct.

Question: 2

Describe the process of fertilization in human beings.

Solution:

Fertilization can only happen with the help of fusion of the male and the female gametes. Male gametes are called sperms and female gametes are called ovum. During fertilization, sperms are released from the male reproductive organ, i.e., the penis and enter the female body through the vagina. Then, they travel through the fallopian tubes. In the fallopian tubes, they meet the eggs and fertilization takes place in the fallopian tubes. During fertilisation, only the nucleus of the sperm and the egg fuse to form a single nucleus. This results in the formation of the zygote, the fertilized egg. After fusion, the sperm degenerates and the zygote further divides to form an embryo, which in turn develops into a foetus.

Question: 3

Choose the most appropriate answer.
(i) Internal fertilization occurs:
(a) in female body.
(b) outside female body.
(c) in male body.
(d) outside male body.

(ii) A tadpole develops into an adult frog by the process of:
(a) fertilization

(b) metamorphosis
(c) embedding
(d) budding

(iii) The number of nuclei present in a zygote is:
(a) none
(b) one
(c) two
(d) four

Solution:

(i) (a)

(ii) (b)

(iii) (b)

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 frogs. ( )
(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)False

(b)True

(c) True

(d) False

(e)True

(f)False

(g)False

(h)True

(i) True

(j)False

Question: 5

Give two differences between a zygote and a foetus.

Solution:

Zygote

Foetus

It is the fertilized egg that is formed after the sperm nucleus fuses with the egg.

It is a stage of the embryo that shows all the main recognizable body parts of a mature organism.

The zygote divides several times to form an embryo.

An embryo gradually develops into a foetus.

It is unicellular.

It is multicellular.

Question: 6

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

Solution:

Asexual reproduction is a form of reproduction where only a single parent is involved. Budding and binary fission are types of asexual reproduction.

Budding: Hydra reproduces by budding, in which an outgrowth arises from the parent and develops into a new individual.

Binary fission: Amoeba reproduces by binary fission in which the parent cell is divided into two new daughter cells.

Question: 7

In which female reproductive organ does the embryo get embedded?

Solution:

The embryo gets embedded in the wall of the uterus.

Question: 8

What is metamorphosis? Give examples.

Solution:

Metamorphosis is a biological process, in which an organism physically transforms from a larva to an adult, through drastic changes. Frogs and silk worms are examples of organisms showing metamorphosis. 

Question: 9

Differentiate between internal fertilization and external fertilization.

Solution:

Internal Fertilization

External Fertilization

Involves the fusion of male and female gametes inside the female body

Involves the fusion of male and female gametes outside the female body

Chances of the offspring survival are more. Therefore, a small number of eggs are produced.

Chances of the offspring survival are less. Therefore, a large number of eggs are produced.

Examples: Humans, cows, hens

Examples: Fish, frog, starfish

Question: 10

Complete the crossword puzzle using the hints given below.
Across
1. The process of the fusion of the gametes.
6. The type of fertilization 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 the fertilized egg.
4. These animals lay eggs.
5. A type of fission in amoeba.

Solution:

Across
1. FERTILIZATION
6. INTERNAL
7. BUDS
8. OVARY
Down
2. TESTIS
3. ZYGOTE
4. OVIPAROUS
5. BINARY