Question 23M.1.HL.TZ1.31
| Date | May 2023 | Marks available | [Maximum mark: 1] | Reference code | 23M.1.HL.TZ1.31 |
| Level | HL | Paper | 1 | Time zone | TZ1 |
| Command term | Question number | 31 | Adapted from | N/A |
Which adaptation would allow plants to live in saline irrigated soil?
A. Small, shallow roots
B. Active uptake and compartmentalization of mineral ions to maintain homeostasis
C. Increased transpiration to replace water in stems
D. Leaves with a large surface area for increased photosynthesis
[1]
B
About two thirds of candidates answered this question correctly, but the discrimination index was relatively low. The term 'saline irrigated soil' in the stem of the question may have confused some candidates. The expected answer includes the word 'homeostasis' which is unusual in relation to plants, as they do not maintain constant internal conditions in the precise way that many animals do. Also the term 'compartmentalization' in relation to storage of mineral ions in halophytes may not have been familiar to candidates. This is an example of a question where the best strategy is to eliminating all the answers apart from the one that must be correct and the three distractors were undoubtedly incorrect.