Question 1
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 |
Show mark scheme for question 1
- increase = 36 − 18 = 18 breaths per minute (1)
- 18 ÷ 18 × 100 (1)
- 100% (1)
Question 2
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean(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]
Show mark scheme for question 2
- (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)