Lesson 1 – The Life Cycle of Animals
(A) Think and tell.
1. It takes 20-22 days for a chick to emerge from a hen’s egg. Would the young ones of other birds also take the same number of days to hatch?
Ans: Every bird has a unique time to hatch. Even if a hen’s egg hatches in 20 to 22 days, different birds take a different number of days to hatch out. For example, a Crow takes 16 to 17 days, a sparrow takes 11 to 14 days, pigeons take 17 to 19 days, and a peacock takes 27 to 29 days. The least period for hatching is 11 days, while the maximum number of days for hatching eggs is 64 days, as in penguins.
2. You must have seen dragonflies hover over grass. Which stage of their life cycle is this – the egg, larva, pupa or adult?
Ans: Dragonfly is the adult stage.
3. When you take a bunch of a leafy vegetable to sort it, you may find holes of different sizes in the leaves. Some leaves may have been nibbled at the edges. What do you think is the reason for that?
Ans: Some insects lay their eggs on the leaves of vegetables. These eggs grow into caterpillars. These caterpillars nibble at the leaves. Due to this, there are holes in the leaves and nibbled edges. Some types of snails also nibble at leaves, as this is their favorite food.
4. When you shell peas, you sometimes see tiny green living things inside the pod. Which of the four stages of the life cycle of an insect are they?
Ans: The tiny green living things which are seen inside the peapod are larvae or caterpillars of some insect. They feed upon the peas and later become adult insects.
(B) Answer in brief.
1. Why must the hen sit on her eggs?
Ans: The chicks grow inside the eggs. They need warmth for growth. Therefore, the mother hen sits on the eggs to provide warmth. This warmth helps the chick grow and hatch. Therefore, the hen must sit on her egg.
2. Why does a hen become aggressive when she is hatching her eggs?
Ans: Hen is alert, and she fears for the safety of her eggs. So in order to protect the eggs from other animals, she becomes aggressive when she is hatching eggs.
3. Which are the four stages of the life cycle of a butterfly?
Ans: Egg larva, caterpillar, pupa, and adult are the four stages of the life cycle of a butterfly.
4. Which changes take place inside the chrysalis of the Plain Tiger butterfly?
Ans: The plain tiger butterfly pupa stops feeding completely and shows the following changes in the body:
(i) It grows longer.
(ii) It develops attractive wings.
(iii) The body grows completely, and the pupa turns into an adult butterfly.
(C) True or false?
1. A lamb emerges from an egg.
Ans: False
2. We cannot easily see the eggs of an ant because they are very tiny.
Ans: True
3. When the caterpillar emerges from the egg, it is not very hungry.
Ans: False
(D) Fill in the blanks.
1. The female butterfly lays ________ on the leaves of a plant.
Ans: eggs
2. The larva of a butterfly is called a ________.
Ans: caterpillar