DP Biology (last assessment 2024)
Question 18M.3.HL.TZ2.3c
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.3.HL.TZ2.3c |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | c | Adapted from | N/A |
c.
[Maximum mark: 2]
18M.3.HL.TZ2.3c
The graph shows the effect of relative humidity on the transpiration rate in Chinese privet (Ligustrum sinense).
The rate of water uptake was measured using the potometer shown in the diagram. The diameter of the capillary tube is 1 mm.
(c)
Explain the effect of relative humidity on the rate of water uptake.
[2]
Markscheme
a. increased «relative» humidity decreases water uptake
OR
inverse relationship
b. increased «relative» humidity lowers transpiration «rate»
c. diffusion gradient reduced «as humidity increases»
d. less loss of water through stomata
OR
stomata closed
Accept inverse for dry/low humidity.
