The graph shows the rates of water loss for three plants, D, E and F, during the first 14 minutes of an experiment. The plants are of different species and are growing in identical conditions. [Figure 3.1]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

1. [1] transpiration / evaporation / diffusion;
2. [1] numbers / size / surface area + leaves ;
3. [1] numbers of stomata ;
4. [1] sizes of stomata / degree to which stomata are open ;
5. [1] rates of water uptake / number of root hairs ;
6. [1] sizes of plant ;
7. [1] thickness of cuticle ;
8. [1] hairs / sunken stomata ;
9. [1] E (drawing) gradient increases for minimum of 2 minutes ;
10. [1] F line with a reduced gradient / horizontal line to 24 minutes ;
11. [1] E increase + water loss / transpiration / evaporation / diffusion ;
12. [1] E water (vapour) removed / humidity decreases ;
13. [1] E increased concentration gradient ;
14. [1] F decrease + water loss / transpiration / evaporation / diffusion ;
15. [1] F photosynthesis decreases / stops ;
16. [1] F guard cells lose their turgidity;
17. [1] F stomata close / stomata not open ;
18. [1] F humidity increases ;
19. [1] F decreased concentration gradient ;