Air and the respiratory system

The air that we breathe contains mainly ___________________.

• oxygen

• carbon dioxide

• nitrogen

• water vapour

About _______________% of air is oxygen.

• 80

• 60

• 40

• 20

For photosynthesis to happen in plants, the plants need light, ______________ and ____________.

• carbon dioxide, water

• carbon dioxide, space

• oxygen, water

• oxygen space

The organ in the human body that helps to remove carbon dioxide in our blood is _____________.

• heart

• lungs

• nose

• windpipe

Tiny openings (stomata) are found mainly on the underside of leaves to __________.

• prevent minerals from evaporating too quickly

• prevent water from evaporating too quickly

• prevent carbon dioxide from escaping too quickly

• prevent oxygen from escaping too quickly

Which of the following activities will result in a person having the fastest rate of breathing?

• Jogging around

• Running around the field

• Walking up the stairs

• Reading a book

What will happen to a plant if the leaves are coated with a layer of oil after a week?

• The plant will remain healthy.

• The leaves of the plant remain shiny.

• The plant will die.

• The leaves of the plant grow bigger.

Why do fish have gills that have many layers of long tiny strips?

• To allow water to flow smoothly

• To provide a larger surface area for gaseous exchange

• To block the water from flowing smoothly

• To provide a smaller surface area for gaseous exchange

Which of the following statements about air is/are correct? You may choose more than 1 statement.

• Oxygen takes up the most amount of air in the Earth's atmosphere.

• Air is made up of nitrogen, oxygen and carbon dioxide.

• Oxygen can be found in water and soil.

• Living things cannot survive without oxygen.

If (a)   is present, a glowing splint will rekindle.