CBSE Class 4 Science Reproduction in Animals Assignment Set 01

Answer: Incubation is the process of keeping eggs warm, usually by a parent bird sitting on them, until the young ones hatch.

Teacher's Note:
1. Warmth is needed for the embryo inside the egg to grow. Birds such as hens and pigeons incubate their eggs.
2. Without incubation most bird eggs would not hatch.

Answer: Metamorphosis is the change of a young one into an adult that looks completely different. Examples: a tadpole becoming a frog and a caterpillar becoming a butterfly.

Teacher's Note:
1. The young and the adult look very different from each other.
2. Insects and frogs are common animals that show metamorphosis.

Answer: Spawn is a jelly-like cluster of eggs laid by animals such as frogs and fish.

Teacher's Note:
1. Spawn is usually laid in water.
2. Each egg in the cluster can grow into a tadpole or a young fish.

Answer: Moulting is the shedding of old skin or body covering and replacing it with a new one. Cockroaches and grasshoppers moult (so do butterfly caterpillars).

Teacher's Note:
1. Animals moult because their old covering becomes tight as they grow.
2. Snakes also shed their skin in the same way.

Answer: Mammals are animals that give birth to young ones and feed them with their own milk. Examples: human beings and lions.

Teacher's Note:
1. Most mammals have hair on their bodies.
2. Mammals breathe with lungs.

Answer: Reproduction is the process by which a living thing produces more living things of its own kind.
1. Oviparous animals lay eggs from which the young hatch, e.g. birds, frogs, fish, snakes.
2. Viviparous animals (mammals) give birth to young ones directly, e.g. dogs, cats, cows.

Teacher's Note:
1. Reproduction keeps a kind of living thing from dying out.
2. The two ways are egg-laying and giving birth.

Answer: 1. Egg shell: thin, hard outer layer that gives shape and protects the egg.
2. Membranes: two thin layers under the shell that give extra protection.
3. Albumen: jelly-like white part rich in protein that protects the yolk and feeds the embryo.
4. Yolk: yellow part rich in fats, vitamins and minerals that feeds the embryo.
5. Chalazae: thick cord-like strands that hold the yolk in place.

Teacher's Note:
1. The embryo grows from the yolk side of the egg.
2. Remember the order from outside to inside: shell, membranes, albumen, yolk.

Answer: 1. Aquatic mammals live in water; terrestrial mammals live on land.
2. Aquatic mammals generally have no hair; terrestrial mammals have hair.
3. Aquatic mammals have streamlined bodies for swimming; terrestrial mammals do not.
4. Some aquatic mammals have flippers; terrestrial mammals have no flippers.
5. Examples: whales and dolphins (aquatic); lions and monkeys (terrestrial).

Teacher's Note:
1. Both groups give birth to young ones and feed them milk.
2. A streamlined body helps an animal move quickly through water.

Answer: laying eggs

Teacher's Note:
1. Birds are oviparous animals.
2. Their young ones hatch from eggs.

Answer: spawn

Teacher's Note:
1. Frogs lay their eggs in water.
2. Tadpoles come out of the spawn.

Answer: on the ground

Teacher's Note:
1. Lizards are reptiles that lay their eggs on land.
2. Frogs and fish, in contrast, lay eggs in water.

Answer: mammals

Teacher's Note:
1. Milk is made in the mother's body.
2. Cows, cats and humans are mammals.

Answer: lungs

Teacher's Note:
1. Even aquatic mammals such as whales breathe air through lungs.
2. They come to the surface to breathe.

Answer: Any two, e.g. hen and frog (also fish, snake, butterfly).

Teacher's Note:
1. Egg-laying animals are called oviparous.
2. Eggs may be laid on land or in water.

Answer: Any two, e.g. dog and cow (also cat, human being).

Teacher's Note:
1. These animals are called viviparous.
2. All of them are mammals.

Answer: Whale and dolphin (porpoise is also correct).

Teacher's Note:
1. Aquatic mammals live in water but are not fish.
2. They give birth to young ones and feed them milk.

Answer: Any two, e.g. frog and fish.

Teacher's Note:
1. Their eggs are often soft and jelly-covered.
2. This is why their eggs are called spawn.

Answer: Any two, e.g. cockroach and grasshopper (also butterfly caterpillar).

Teacher's Note:
1. These animals shed their outer covering as they grow.
2. The new covering is formed underneath the old one.

Answer: The yolk.

Teacher's Note:
1. The yolk is the yellow part inside the albumen.
2. The albumen gives extra protein.

Answer: The chalazae.

Teacher's Note:
1. They are thick cord-like strands.
2. They keep the yolk from shaking about.