A plant breathes in carbon dioxide and

breathes out oxygenthrough its stoma.

How do plants breathe?

stomata

Stomata are tiny pores on the surfaces of leaves that permit the exchange of gases between the atmosphere and the inside of the leaf

Photosynthesis

At night time, plants can not make food, so they shut down by closing their stomata. 

Remember:

All parts of the plant breathe. -the leaves, the stem, the roots and even the flowers.

The roots of a plant also need oxygen which they obtain from the air spaces in the soil.

How do fish breathe?

Through the gills, fish are able to absorb oxygen and give off carbon dioxide.

The fish gills are made up of tiny flaps that are rich in blood.

GILLS

How do people breathe?

lungs

When you breathe in, fresh air goes into your lungs.

When you breathe in (inhale) through your mouth or nose, air travels down your windpipe and into your lungs.

The lungs are protected by the ribs

Workbook p 106

a. Label the chart to show the composition of air by percentage:2.

_____

______

b. What is the amount of water vapour in the air?

The amount depends on the time and place it is measured.

3. Fill in the blanks

To put out a fire, we can use either or both of the following methods:

a. Method A - Cut off the supply of oxygen.b. Method B – Increase the supply of carbon dioxidec. Pailin poured a bucket of sand over a small fire. Which method

didshe use, A or B? Method A

Workbook page 106

4. a. Plants can breathe only through the stomata on their leaves. b. Sharks like seals and dolphins, need to get out of the water to breathe. c. Oxygen is taken into the body and carbon dioxide is removed from the body when we breathe. d. Water flowing out of the gills of a fish contains less oxygen than the water entering its mouth.

__________

____________________

F

F

T

T

5. (a) Suggest why we have to come out of the water to breathe when we are swimming although there is air in the water?

We breathe with lungs which are unable to take in air from water.

(b) How does a snorkel help us to swim underwater?

A snorkel has a tube that sticks out of the water surface to get air.

6. Complete the crossword puzzle

workbook page 108

Acrossa. The organs used by humans to breathe.b. Tiny holes on the underside of leavesc. The gas needed for burningd. Air that is moving

Downe. The gas used to make fertilizersf. The organs used by fish to breatheg. The organ through which air enters or leaves a human

ITROGEn

a. L U e. N G S

ITROGEN

b. S T O M A T A

c.O X Y f.G E g.N

d.W I N D

ILLS

OSE

workbook page 109Breathing in:

Breathing out:Air rich in oxygen enters the (i)______

Air goes down the (ii)_________ and into the smaller (iii) ___________

(v) __________ from the air that is breathed in is taken into the bloodstream. Unwanted (vi) _______________ from the body is removed.

Air goes out of the body through the (x)_____________

Air with less (viii)__________________ and richer in (vii)

____________ goes into the air tubes

Air goes up the (ix)________________

Air goes into the (iv) _________________

nose

windpipe

lungs

Oxygen

carbon dioxide

oxygen

carbon dioxide

windpipe

nose

airtubes