Gaseous exchange

Question 1

Where is the breathing system located?

Answer 1

In the thorax (the upper part of the body).

Question 2

What does the ribcage do?

Answer 2

It protects the breathing system.

Question 3

What divides the thorax from the abdomen?

Answer 3

A muscular sheet called the diaphragm.

Question 4

Why does the breathing system take air into and out of the body?

Answer 4

1. So that oxygen from the air can diffuse into the blood.

2. So that carbon dioxide can diffuse from your blood into the air.

Question 5

What is the trachea?

Answer 5

An organ through which the air that is breathed in reaches the lungs. It has rings of cartilage to prevent it from collapsing.

Question 6

What is the set-up of the organs in the lungs?

Answer 6

1. The trachea divides into two tubes; the bronchi.
2. The bronchi divide to form bronchioles.
3. The bronchioles divide until they end in air sacs called alveoli.

Question 7

Why are the alveoli efficient at exchanging oxygen and carbon dioxide?

Answer 7

1. They are very close to the blood capillaries, which means that they have an excellent blood supply.
2. They have a large, moist surface area.

Question 8

What is ventilation?

Answer 8

The movement of air into and out of your lungs.

Question 9

What happens when you inhale?

Answer 9

You breathe in.

1. Your ribcage moves up and out.
2. Your diaphragm flattens (contracts).

Question 10

What happens when you exhale?

Answer 10

You breathe out.

1. Your ribcage moves down and in.
2. Your diaphragm moves up (relaxes).

Question 11

Why have artificial aids for breathing been developed?

Answer 11

For medical use; to improve gas exchange in the body.

Question 12

How does carbon dioxide enter a plant?

Answer 12

By diffusion into the leaves.

Question 13

How do water and mineral ions enter a plant?

Answer 13

By absorption through the roots.

Question 14

How are roots adapted to carry out the exchange of materials?

Answer 14

Root hairs provide a large surface area in roots.

Question 15

How are leaves adapted to carry out the exchange of materials?

Answer 15

Leaves are broad, thin and flat with lots of internal air space to provide the largest surface area possible.

Question 16

What are stomata?

Answer 16

Tiny holes on the leaves of a plant.

Question 17

What do the stomata do during photosynthesis?

Answer 17

1. They let carbon dioxide in.

2. They let oxygen out.

Question 18

Describe the cross section of a leaf.

Answer 18

From top to bottom:

1. Wax cuticle.
2. Upper epidermis.
3. Palisade cells.
4. Spongy mesophyll with air spaces.
5. Lower epidermis.
6. Stomata.
7. Guard cells.
8. Wax cuticle.

Question 19

Where do plants mainly lose water?

Answer 19

From their leaves, through the stomata.

Question 20

What is transpiration?

Answer 20

The movement of water through a plant.

Question 21

In what conditions is the evaporation of water more rapid?

Answer 21

Hot, dry, windy conditions.

Question 22

What happens when plants lose water faster than it’s replaced?

Answer 22

The stomata close to prevent wilting and photosynthesis stops.

Question 23

What happens to a plant in cool, damp, not windy conditions?

Answer 23

1. The stomata open to allow transpiration and diffusion of gases. This means that plant cells become full of water so the plant stays erect.
2. There is plenty of water in the soil so the surface area of the roots is increased by root hairs.

Question 24

What happens to a plant in hot dry, windy conditions?

Answer 24

1. The stomata close to prevent transpiration and photosynthesis has to stop. This means that plant cells become short of water so the plant wilts.
2. There isn’t enough water in the soil so the surface area of the roots is increased by root hairs.

Question 25

What is the function of the guard cells?

Answer 25

They surround the stomata and control stomata size.

Question 26

What happens to your ribcage when you breathe in?

Answer 26

Moves up and out.

Question 27

Where does gas exchange occur in the lungs?

Answer 27

In the alveoli (air sacs).

Question 28

Name the process of water movement in plants.

Answer 28

Transpiration.

Question 29

Name the cells that open and close stomata.

Answer 29

Guard cells.