Pupil sheet · Gas exchange and breathing

Gas exchange and breathing — final check

Name ______________________ Date ____________

Work alone, with the lesson closed. Answer every question; there are no hints.

1. describe

Describe how the two-tube apparatus is used to compare the carbon dioxide in inspired and expired air, and how the result is judged fairly.

2. identify

A gas analyser tests four samples of air, and a sensor compares their water vapour with room air. Which row could be a sample of expired air?

Row	Oxygen / %	Carbon dioxide / %	Water vapour compared with room air
A	3.8	16.9	more
B	20.9	0.04	more
C	16.9	3.8	more
D	16.9	3.8	less

Circle one answer.

3. explain

Supplement. Explain why expired air contains less oxygen than inspired air.

4. identify

The diagram shows part of the breathing system, seen in a new way. Match each number to the name of the part. Two of the names are not used.

Part of the breathing system, seen from the front with one half of the chest opened, with ten parts numbered. 3 points to the box-shaped top of the airway, in the neck. 6 points to a ring halfway down the tube below it. 10 points to the wide branch that leads into the large organ on the right, 7. 2 points to a narrow branch low inside 7, on its left side. 4 points to the third oval section from the top at the outer side, and 8 to the striped band between the third and fourth sections. 1 points to the curved band under 7, near its lowest point. A circle at the upper left magnifies the end of a narrow branch: 9 points to the air space inside one round sac, and 5 to the dark end of the fine vessel curving round it.

Write the number of the matching option.

oesophagus
alveolus
larynx
intercostal muscle
bronchus
heart
capillary
trachea
rib
bronchiole
lung
diaphragm

1: ______
2: ______
3: ______
4: ______
5: ______
6: ______
7: ______
8: ______
9: ______
10: ______

5. explain

Explain how two features of the alveoli make gas exchange fast.

(a) First feature and how it helps

(b) Second feature and how it helps

6. identify / state / explain

Supplement. (a) The diagram shows a section through the chest wall. Identify the letter that shows the muscles that pull the ribs down and in, and state their name. (b) State the function of the cartilage in the trachea. (c) Explain the role of mucus and cilia in protecting the lungs.

A section through the chest wall, not to scale, with the outside of the body on the left and a lung on the right. Three ribs lie one above another, with two layers of muscle in each gap between them, their fibres slanting in opposite directions. F points to the layer nearer the outside of the body; G points to the layer nearer the lung.

(a) Muscles

(b) Cartilage

7. explain

Supplement. Explain how the ribs, intercostal muscles and diaphragm cause air to enter the lungs.

8. calculate

Straight after exercise, a pupil breathes 28.8 dm³ of air per minute at a rate of 18 breaths per minute. (a) Calculate the depth of each breath. (b) At rest, the depth of her breaths is 0.6 dm³. Calculate how many times deeper her breaths are after exercise. Give your answer to 2 significant figures.

(a) Depth of each breath: ______________ unit ________

(b) How many times deeper: ______________ unit ________

9. describe

Describe how you would investigate the effect of physical activity on the rate of breathing, and the result you would expect.

10. explain

Supplement. A cyclist reaches the top of a steep hill and stops to rest. Over the next few minutes her breathing becomes slower and shallower. Explain why.