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?
What Is Fertilisation? Where Does It Take Place?
- 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.
Mention the Gestation Period of the Following Animals— Elephant, Dog, Giraffe, Monkey, Kangaroo, Cat, Rhinoceros.
|ii.||Dog||2.5 to 3 months|
|iv.||Monkey||Around 5 months|
What Protects the Growing Baby From External Physical Shocks in Mammals?
- 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
What Is the Meaning of Life Span? Give Examples.
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.
Metamorphosis in Frog Is Controlled by Iodine. Why?
- 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.
How Does the Larva of a Butterfly Survive Without Feeding in the Pupa Stage?
- 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.
Why Is Water Essential in the Life Cycle of a Frog?
- 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.
Why Do Some Animals Show Metamorphosis?
- 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.
What Is Parthenogenesis?
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.
What Is Binary Fission?
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.
What Do You Understand by Bisexual Organisms?
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.
How Does a Growing Foetus Obtain Nourishment From the Mother’s Body?
- 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