Class 4th Science work ch 3 to 7

 Ch 3 Reproduction in animals

Keywords

1. Mammals: Animals that give milk and give birth to young ones

2. Reptiles: Animals that lay eggs and crawl on the ground

3. Moulting: removing old skin

4. Metamorphosis: the process of transformation from an immature state to an adult.

Answer the following questions

Q1. What is reproduction?

Ans. A process in which species produce of their own kind.

Q2. Why do animals reproduce?

Ans. Animals reproduce to maintain their continuity.

Q3. What helps an embryo to nourish inside a birds egg?

Ans. Yolk nourish embryo inside the egg.

Q4. Why do birds sit on their eggs?

Ans. They sit on their eggs to provide warmth to the egg.

Q6.How do mammals take care of their young ones?

1. They feed their young ones with milk

2. They protect them from enemies.

3. They help them to find food

4. They teach them to live their own

5. Males hunt for food

Q7. What are the different stages of development in a frog? Name the process by which a tadpole terms into an adult?

Ans. The life cycle of a frog includes spawn, tadpole, young frog and adult frog🐸.  The process of growing into an adult frog from a tadpole is called metamorphosis.

Q8. What are the different stages of development in a frog? Name the process by which a tadpole turns into an adult.

Ans. Spawn, tadpole, young frog and adult frog are the stages in the life cycle of a frog. The process of changing a tadpole into an adult frog is called metamorphosis.

Q9. Explain the life cycle of a butterfly. Support your answer with a diagram.

Ans. In a life cycle of a butterfly, there are four major stages. Eggs, caterpillar, pupa and adult butterfly.

Chapter 4                        Adaptation in animals

Keywords

1. Adaptation: the ability to change to suit the environment

2. Hibernation: a long winter sleep of animals

3. Parasites: animals that live within and on the bodies of other animals

4. Camouflage: the ability to merge with the surrounding

Answer the following questions

Q1. Name the types of animals on the basis of their habitat

Ans. Terrestrial animals, aquatic animals, Amphibians, Aerial animals and Arboreal animals.

Q2. Why adaptation is necessary for all living beings?

Ans. Adaptation is necessary for all living beings to survive in nature.

Q3. What are herbivores?

Ans. Animals that eat only plants.

Q4. What do you mean by carnivores?

Ans. Animals that eat only the flesh of other animals.

Q5. What are omnivores?

Ans. Animals that eat both flesh and plants

Q6. List some features of terrestrial animals.

Ans. Terrestrial animals have

1. Limbs to move

2. Lungs to breathe

3. Hair to bear heat and cold

4. Well developed nervous system

5. Sense organs

Q7. How camel is adapted to live in a desert?

Ans.

1. Camel has padded feet to move on sand

2. Hump is used to store fat

3. Eyelashes provide protection for the eyes

Q8. Which features of an aerial animal help it to fly?

Ans.

1. They have hollow bones

2. They have a boat-shaped body

3. They have feathers to fly

Q9. How is a frog adaptor to live both on land and in water?

Ans. Frogs have

1. Limbs to move and swim

2. Gills and lungs to respire

3. Moist skin to breathe in water

Q10. How is a polar bear adapted to live in an extremely cold region?

Ans. Polar bear has

1. Thick fur for protection from cold

2. Sharp claws for finding food

3. Fatty skin for protection from cold

Chapter 5 food and digestion

Keywords

1. Balanced diet:  a diet containing all the nutrients in the right proportion

2. Digestion: the process of breaking down food into simple substances

3. Dehydration: removal of water from a body

4. Roughage: the fibre present in the food

Answer the following questions

Q1. Name the nutrients of a balanced diet.

Ans. Carbohydrates, fats, proteins, vitamins and minerals.

Q2. How food can be preserved?

Ans. Food can be preserved in the following way

1. By freezing it

2. Can it as tinned food

3. Salt it as pickles

4. Sweeten it as Jam

5. Oil it as pickles

6. Dehydrate food

Q3. Why is water important for our body?

Ans.

1. Water helps in digestion

2. Water transport nutrients

3. Water removes Toxic substances

Q4. Why should we not throw the water in which pulses are soaked?

Ans. Because it contains nutrients

Q5. What is the advantage of cooking food?

Ans. Cooking makes the food tasty, soft

 and easy to digest.

 Q6. How are proteins and carbohydrates useful?

 Ans. 1. Carbohydrates provide energy to do work

 2. Proteins help in the growth and repair the wear and tear of the body.

Q7. Define roughage? Why should it be included in a diet?

Ans. Roughage is the fibres in a diet. They help in digestion.

Q8. Write four ways for easy digestion

Ans. 1. Take food at regular intervals

2. Chew food properly

3. Do not swallow the food

4. Have a balanced diet

5. Drink plenty of water

6. Include roughage and fruits

7. Do not overeat

8. Wash your hand before and after eating

Q9. Why vegetables and fruits should be washed before cutting them

Ans. This is because washing after cutting removes some vitamins and minerals

Q10. Junk food is not nutritious. Why?

Ans. This is because junk food does not provide the essential nutrients to the body.

Chapter 6 Teeth and Microbes

Keywords

1. Enamel: the outermost layer of the teeth

2. Dentine: the layer below the enamel

3. Germs: disease-causing microorganisms

4. Cavity: a hole in the tooth

Answer the following questions

Q1. How are teeth important to us?

Ans. Teeth help in cutting, tearing and chewing the food.

Q2. Name the two sets of teeth

Ans. Temporary teeth and permanent teeth

Q3. What is the result of tooth decay?

Ans. It causes plaque and a cavity on the tooth.

Q4. Name the sticky layer with germs on the teeth.

Ans. Plague is the sticky layers with germs on the teeth.

Q5. Name the hardest substance in our body.

Ans. Enamel

Q6. Name the different kinds of teeth and state their functions.

Ans. Incisors: teeth that are used to cut the food

Canines: teeth that are used to tear the food

Premolars: teeth that are used to crush the food

Molars: teeth that are used to grind the food

Q7. List three ways in which bacteria are useful to us

Ans. 1. Some bacteria change milk into curd

2. Yeast help to bake soft bread

3. Bacteria help in the decomposition of dead animals and plants

4. Bacteria digest roughage in animals

Q8. Name the layers of the teeth. Support your answer with the diagram.

Ans. The layers of teeth are enamel, dentine and pulp.

Q9. What are microbes? Name different kinds of microbes.

Ans. The organisms which can be seen only under a microscope are called microbes. Bacteria, viruses, protozoa, fungi and algae are the kinds of microbes

Chapter 7     Clothing: our basic need

Keywords

1. Fabric: a woven material of textile

2. Natural: material found in nature

3. Synthetic: a material made artificially by man

4. Detergent: a soluble substance used for washing clothes

Answer the following questions

Q1. How are clothes useful to us?

Ans. Clothes protect us from heat, cold, rain, dust and insect bites.

Q2. Name the kinds of fibre used to make different fabrics

Ans. Wool, silk, fur, cotton, linen, nylon rayon, polyester etc. are used to make different kinds of fabrics.

Q3. Why do some people wear special clothes?

Ans. Some people wear special clothes for their identity. For example, the doctor wears the white colour of clothes.

Q4. What are the special qualities of synthetic fabrics?

Ans. Special qualities of synthetic fibre

1. Some are waterproof.

2. Some of them are wrinkle-free

3. Some are Stretchable

4. They are long-lasting

5. They are cheap than natural fabrics.

Q5. How are natural fibres different from man-made fibres? Give some examples.

Ans. Natural fibres are obtained from animals and plants. For example cotton and wool

Synthetic fibres are obtained from chemicals. For example nylon and polyester

Q6. How can you take care of your clothes?

Ans. 1. Clothes should be washed properly.

2. Use soap and water to wash them

3. Clothes should not be very tight

4. Clothes must be ironed before use

5. Do not wear wet clothes.

Q7. How should you store your clothes?

Ans. 1. They must be dry cleaned before being packed

2. They should be packed with mothballs

3. Proper packing of the clothes should be done.