CLASS 3 – G. SC. NOTES

1st TERM

Unit 1: THE HUMAN BODY

ANSWER THE FOLLOWING QUESTIONS

Q1. What does your skin do?

Ans : Our skin does many different jobs;

1. The skin holds everything else inside our body.

2. The skin protects the other parts of our body from diseases.

3. The skin makes sure that our body is kept at the right temperature.

4. The skin provides us with our sense of touch.

Q2. What part does the brain play in helping you see?

Ans: The brain turns the image the right way around.

Q3. What do the eyelids and eyelashes do?

Ans: The eyelids close quickly if the brain senses danger to the eyes. Eyelashes trap dust and

other tiny particles.

Q4. How do you see an image?

Ans: Images are inverted on their way to the retina at the back of the eye. Then brain turns

the image the right way around.

Q5. How does the brain help you to hear?

Ans: The brain helps to make sense of sounds.

Q6. What are the different sections of the human ear? What does each section do?

Ans: The human ear has three main sections.

1) The outer ear

2) The middle ear

3) The inner ear

1)The outer ear:

It collects sounds as they pass by the ear.

2) The middle ear:

The sounds then make their way into the middle ear where it hits the eardrum

which turns the sounds into vibrations.

3)The inner ear:

The vibrations move into the inner ear where they are sent to the brain where it

makes sense of the sounds.

Q7. What job does the nose do?

Ans: The nose has three main functions.

1) It helps us to breathe.

2) It allows to smell the world around us.

3) It allows to taste what we are eating.

Q8. What type of organ is the tongue?

Ans: The tongue is a muscle. It helps to chew and swallow the food. It has taste buds on its

surface that taste the different flavours of food.

Q9. Choose the best answer.

1) The tongue helps to swallow the food. (nose, tongue)

2) Nose allows us to smell the world around us. (smell, chew)

3) When we sneeze, there is irritation inside the nose. (eat, sneeze)

4) There are taste buds on the surface of the tongue. (flowers, buds)

5) Our eyes are the same size now as they were when we were born. (legs, eyes)

6) The smallest bones in the human body are in the ear. (heart, ear)

Q10. Write the missing letters.

1) Vibrations

2) Stirrup

3) Anvil

4) Sneeze

5) Temperature

6) Diseases

UNIT 5 – THE ENVIRONMENT

Q1. Fill in the blanks.

1) There are different types of habitat on Earth.

2) Cities are a man-made habitat.

3) Deserts do not get much rain.

4) Most deserts have extreme temperature.

5) Snow leopards in Pakistan are endangered.

Q2. Choose the best answer.

1) We need to drink clean water. (throw, drink)

2) The Earth should be clean because many things live and grow on it. (Earth, stars)

3) Seas and rivers are the habitat of many animals. (Habitat, plant)

4) Animals that live in the Polar regions have to have lots of fur, thick feathers, or a layer

of fat. (Polar regions, Equator)

5) Desert animals can survive a long time without much water. (short, long)

ANSWER THE FOLLOWING QUESTIONS

Q1. Do you know the name of the largest sandy desert in the world?

Ans: The Sahara Desert in Africa is the largest sandy desert in the world.

Q2. What is the difference between a natural habitat and a man-made habitat?

Ans: Forests and Deserts, Seas and Rivers are natural habitats for many animals, while

cities are man-made habitats because humans have changed the natural habitat to create a

new one.

Q3. Why is it important to keep the air clean?

Ans: It is important to keep the air clean because humans and animals need to breathe clean

air. If the air is not clean, humans and animals may become ill and even die.

Q4. What are the main causes for species becoming endangered?

Ans: The main causes for species becoming endangered are;

1) Humans have destroyed their habitats like cutting down trees in forests and clearing

land for agriculture.

2) Humans have brought in animals or plants from other parts of the world where they

cannot survive.

Q5. What is the difference between being endangered and being extinct?

Ans: Being endangered means that species are at a risk of dying out completely. Extinct

means that a certain species no longer exist on Earth.

● Workbook page no. 15, 16, 17 and 18.

A

adapt

UNIT 9 HEAT AND LIGHT

Q1. Fill in the blanks.

1) Heat is produced when molecules start moving.

2) The temperature of a substance tells us how hot or cold it is.

3) The length of a light wave depends on its colour.

4) Each colour has waves of a different length.

5) Violet light waves are the shortest light waves.

Q2. Choose the best answer.

1) Light travels in straight lines called rays. (blocks, rays)

2) A collection of rays is called a beam. (collection, separation)

3) We cannot see non-luminous objects in the dark. (dark, light)

4) The Sun is a luminous object. (Sun, book)

Q3. Matching

1) Water boils at thermometer

2) Water freezes 100°C

3) Measuring temperature 0°C

4) Candle straight lines

5) Light travels luminous

ANSWER THE FOLLOWING QUESTIONS

Q1. What is temperature? How is it measured?

Ans: The temperature of a substance tells us how hot or cold it is. There are two main

scales for measuring temperature.

1) Celsius

2) Fahrenheit

Q2. Explain why ice cream melts?

Ans: Ice cream melts because heat is transferred from the surroundings to the ice cream.

Q3. How does light travel? Explain with diagrams.

Ans: Light travels in waves. The length of a light wave depends on its colour. Each colour

has waves of a different length. When the waves of all colours are seen together, we see

white.

(Diagram page 62, fig#9.2)

Q4. How is a shadow formed?

Ans: When something gets in the way of light, the light is blocked. This is how a shadow is

formed.

Q5. What is the difference between luminous and non-luminous objects?

Ans: The objects that give out light of their own are called luminous objects. e.g. The sun, a

fire, and candle.

The objects that do not give out light of their own are called non-luminous objects. e.g. a

book, a chair, a key.

Workbook page no. 30, 32 and 33.