Question 1
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanWhich statement explains why expired air contains less oxygen than inspired air?
- Oxygen is converted into carbon dioxide in the trachea.
- Oxygen diffuses into the blood and is used in respiration.
- Oxygen is stored in the alveoli.
- Oxygen is trapped by the mucus.
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Answer: B – oxygen diffuses into the blood and is used in respiration (1)
Question 2
A student investigates inspired and expired air using two tubes of limewater. (a) State what happens to limewater when carbon dioxide is bubbled through it. [1] (b) State which tube of limewater, the one for inspired air or the one for expired air, turns cloudy faster, and what this shows. [2] (c) Name two other differences in composition between inspired air and expired air, apart from carbon dioxide. [2]
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- (a) it turns cloudy / milky (1)
- (b) the tube for expired air (1)
- expired air contains more carbon dioxide than inspired air (1)
- (c) expired air has less oxygen (1)
- expired air has more water vapour (1) ignore nitrogen / temperature
Question 3
A student counts her breathing rate at rest and after exercise. The results are shown in the table. Calculate the percentage increase in her breathing rate after exercise. Show your working.
| condition | breathing rate / breaths per minute |
|---|---|
| at rest | 18 |
| after exercise | 36 |
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- increase = 36 − 18 = 18 breaths per minute (1)
- 18 ÷ 18 × 100 (1)
- 100% (1)
Question 4
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanExplain how the muscles and the diaphragm cause air to move into the lungs when a person breathes in.
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- external intercostal muscles contract (1)
- internal intercostal muscles relax (1)
- ribs move up and out (1)
- diaphragm contracts and flattens (1) allow: moves down
- volume of thorax increases (1)
- pressure in thorax decreases / lower than atmospheric pressure (1)
- air moves in from higher pressure outside (1) reject lungs expand and suck air in
- Max 4
Question 5
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanExplain why a person's rate and depth of breathing increase during physical activity.
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- muscles respire faster / more respiration (1)
- more carbon dioxide produced / carbon dioxide concentration in blood increases (1)
- this is detected by the brain (1) reject brain detects lack of oxygen
- brain sends signals to the breathing muscles / increases the rate and depth of breathing (1)
- more carbon dioxide removed / more oxygen supplied (1)
- Max 4
Question 6
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean(a) State the function of the cartilage in the trachea. [1] (b) Describe how goblet cells and ciliated cells protect the lungs from pathogens. [2]
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- (a) supports the trachea / keeps the trachea open (1)
- (b) goblet cells make mucus (1)
- which traps pathogens / particles (1) allow: ref. to dust
- ciliated cells (cilia) move the mucus away from the lungs / up to the throat (1)
- Max 2 for (b)
Question 7
(a) Name the structures in the breathing system where gas exchange takes place. [1] (b) Describe three features of the structures named in (a) that make them efficient gas exchange surfaces. [3]
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- (a) alveoli (1)
- (b) large surface area (1)
- thin / walls one cell thick / short diffusion distance (1)
- good blood supply / network of capillaries (1)
- good ventilation with air / breathing (1)
- Max 3 for (b)
Question 8
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanWhich row describes the internal intercostal muscles during forced breathing out?
- On the outside of the ribs; they contract
- On the inside of the ribs; they contract
- On the inside of the ribs; they relax
- On the outside of the ribs; they relax
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Answer: B (1)