Question 18M.3.HL.TZ1.3
| Date | May 2018 | Marks available | [Maximum mark: 5] | Reference code | 18M.3.HL.TZ1.3 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Evaluate, Suggest | Question number | 3 | Adapted from | N/A |
Transpiration in plants can be measured using a bubble potometer or a mass potometer.
Suggest a possible research question that could be investigated using a potometer.
[2]
a. the research question identifies the independent variables
b. the research question identifies the dependent variable/derived value
c. the research question identifies the organism tested
If several variables are given, mark the first one only.
Examples:
a. Effect of changing/increasing wind/temperature/light/humidity/surface area/comparing different species
b. accept transpiration rate
c. accept common names.
Evaluate the limitations of using a potometer in the investigation you suggested in (a).
[3]
a. not all of the water taken up by the plant is used for transpiration
b. some water taken up might be used for photosynthesis/ cell turgidity
c. (bubble) potometer measures rate of water uptake (not transpiration directly)
OR
bubble in potometer may expand due to changes in temperature/pressure
d. (cut) plant/twig gets damaged/may not survive
e. conditions in a lab are not equivalent to those in nature/ difficult to change only one abiotic factor
f. difficult to extrapolate values from a twig to whole plant
