Reproduction in Animals

• The process of giving birth to an offspring is called reproduction.
• Animals have different modes of reproduction— oviparous, viviparous or ovoviviparous.
• Further, based on the number of parents involved, reproduction in animals can be sexual or asexual.
• Sexual reproduction requires two parents, whereas asexual reproduction requires only one parent.

What is the Meaning of Reproduction?

Question 1:

What Is Fertilisation? Where Does It Take Place?

Answer:

• The process of fusion of male and female gametes is called fertilization.
• The site of fertilisation varies in different animals.
• In mammals, it takes place inside the body of the female.
• In fishes, it takes place in water, i.e., outside the body of a female.

Question 2:

Mention the Gestation Period of the Following Animals— Elephant, Dog, Giraffe, Monkey, Kangaroo, Cat, Rhinoceros.

Answer:

Question 3:

What Protects the Growing Baby From External Physical Shocks in Mammals?

Answer:

• The growing baby is enclosed within an amniotic bag filled with amniotic fluid.
• This amniotic fluid protects the growing baby from external physical shocks.

Animal Life Cycle

Question 1:

What Is the Meaning of Life Span? Give Examples.

Answer:

The period from birth to the death of an organism is called its life span. The lifespans of a few animals are given below—

• Dog: 10-13 years
• Elephant: 60-70 years
• Chimpanzee: 15-30 years
• Lion: 15-16 years
• Parrot: Some species of parrots can live up to 100-120 years, whereas some have a smaller life span of around 20 years.

Question 2:

Metamorphosis in Frog Is Controlled by Iodine. Why?

Answer:

• Metamorphosis requires a hormone called thyroxine, secreted by the thyroid gland.
• Iodine is required for the proper functioning of the thyroid gland so that it can secrete the required amount of thyroxine.

Question 3:

How Does the Larva of a Butterfly Survive Without Feeding in the Pupa Stage?

Answer:

• The larva of a butterfly eats voraciously in the second stage of their life cycle, i.e., caterpillar.
• During this stage, the larva stores food in its body in the form of fat.
• Energy is released in the pupa stage by burning the stored fat.
• It helps the larva to survive without eating in the pupa stage.

Question 4:

Why Is Water Essential in the Life Cycle of a Frog?

Answer:

• The frog is an amphibian, and it lays eggs in water.
• The stages in the lifecycle of a frog cannot be accomplished in the absence of water.
• Also, the prominent feature of its life cycle, i.e., metamorphosis, takes place in water.
• Hence, water plays a crucial role in the life cycle of a frog.

Question 5:

Why Do Some Animals Show Metamorphosis?

Answer:

• In some animals, the offspring born is very different from the adult.
• For instance, the tadpole of the frog has gills, whereas the adult frog has lungs.
• To develop features resembling adults, some animals undergo metamorphosis.

Asexual Reproduction

Question 1:

What Is Parthenogenesis?

Answer:

Parthenogenesis is a mode of reproduction in which the eggs directly develop into a new individual without any fertilisation.
Ants and wasps show this type of reproduction.

Question 2:

What Is Binary Fission?

Answer:

Binary fission is a mode of asexual reproduction where the parent individual matures and splits into two identical offspring.
Amoeba, Euglena and bacteria reproduce by the process of binary fission.

Sexual Reproduction

Question 1:

What Do You Understand by Bisexual Organisms?

Answer:

The organisms in which both male and female reproductive organs are present in the same body are called bisexual organisms. Leech and earthworms are bisexual organisms.

Question 2:

How Does a Growing Foetus Obtain Nourishment From the Mother’s Body?

Answer:

• A growing foetus is attached to the mother's body through a cord-like structure called the placenta.
• The exchange of blood takes place between the growing foetus and the mother’s body through this placenta.
• The required nutrients get exchanged with the blood.S