DP Biology (last assessment 2024)
Question 18M.3.HL.TZ1.b
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.3.HL.TZ1.b |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 3]
18M.3.HL.TZ1.b
Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue.
[3]
Markscheme
a. weigh all pieces to ensure same amount of plant material/allow comparisons
b. control surface area by having same shape/ size
c. carry out experiment at same temperature e.g. using a water bath or constant room temperature
d. all samples in solution for same length of time
e. all samples from same plant (to minimize variability)
f. use a range of solutions of the same solute
g. constant method of removing excess fluid before weigh tissue samples
Do not accept just a list of controlled variables.
