Exercise 3

Exercise 2

A Complete Change

Many young animals do not look like their parents. They undergo changes before they look like their parents. Can you name the animals?

Animals have different life cycles. Some young animals look like their parents. For example, hamsters and chick

Reproduce

1) Humans Reproduce

Humans reproduce by giving birth to their offspring. This process continues from one generation to another. When humans reproduce, the number of people increases.

Each family has their own offspring who look more like their parents. Do you look like your parents?

2) Animals Reproduce

How do animals reproduce? Some animals give birth and some lay eggs. Different types of animals reproduce in different ways.

A hen lays eggs. A chick hatches from the egg after a few days. The chick grows to become a hen.

A cow gives birth to a calf. The calf grows in the cow's womb until it is born.

3) Plants Reproduce

Plants reproduce to ensure the survival of their species. They reproduce in many different ways. For example, a papaya plant.

Can you see that this plant has flowers?

The flowers will become fruits that contain seeds in them. When these seeds are planted, they will grow into seedlings and then into young plants.

Some plants reproduce from spores. Ferns and mushrooms produce millions of tiny spores.

These spores can be easily carried away by the wind. They can grow into young plants under the right conditions. 

Bryophyllum and begonia plants reproduce from leaves.

Tapioca and hibiscus plants reproduce from stem cuttings.

Ginger plants reproduce from underground stems.

Breathe

1) Humans Breathe

We learnt that humans need air to breathe. When we breathe, we inhale (take in) and exhale (take out) air. Our chest moves up and down. The number of chest movement is the rate of breathing.

As we inhale, the chest rises outwards and upwards causing the chest to expand. The air is taken in through the nose, down the windpipe into the lungs. This air contains more oxygen.

As we exhale, the chest moves in causing the chest to contract. The air inside the lungs then flows out from the lungs to the windpipe and then out through the nose. This air contains more carbon dioxide.

Look at the diagram. Let us trace how air moves into the lungs and out of the lungs.

The red arrows show how air moves in and the blue arrows show how air moves out.

Humans use their lungs to breathe.

2) Animals Breathe

All animals breathe. Different animals may have different breathing structures. What are the differences in their structures? How do they breathe?

Animals have breathing structures to help them breathe. They need to breathe to stay alive.

Exercise 1

1. The basic needs of humans and animals are                     ,                     ,                    and                   .

2.                 and                       are needed by humans and animals to help them grow and stay healthy.

3. Humans and animals need                      to breathe.

4. Humans and animals have different types of                         to protect themselves from danger, the sun and the rain.

5. The basic needs of plants are                    ,                     and sunlight.

6.   Figure 1 shows an experiment carried out by a group of pupils.

a) What is the purpose of this experiment? 

b) In this experiment,

ž What is changed?

ž What is kept the same?

c) What do u think will happen to the caterpillar in jar X?

d) Give a reason for your answer in (c).

Basic Needs of Plants

Look at the plants below. They are placed in different condition.

Which of the above plants can survive longer without the basic needs?

1. Plants need sunlight to stay alive.

2. They also need air to stay alive. Without air, plants will die.

3. žPlants absorb water from the soil through their roots.

4. žThey will wilt and die if they do not get any water.