Question 19M.1.HL.TZ1.34
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1.HL.TZ1.34 |
| Level | HL | Paper | 1 | Time zone | TZ1 |
| Command term | Identify | Question number | 34 | Adapted from | N/A |
Which statement describes the control of reproduction in flowering plants?
A. Flowering in short-day plants results from changes in gene expression in the shoot apex.
B. Flowering in long-day plants is controlled by the production of auxins in the shoot apex.
C. All flowering plants depend on the duration of periods of light and darkness to regulate the timing of reproduction.
D. Flowering in short-day plants occurs when day length is longer than 12 hours.
[1]
A
Although this question attracted almost no comments from teachers, the statistics show that it was problematic. Only 6 % of candidates chose the answer that the examining team considered correct and not surprisingly the discrimination index was very low. Sub-topic 9.4 of the programme includes the Understanding that flowering involves a change of gene expression in the shoot apex. This was answer A. 77 % of candidate instead chose C. Although many plants use periods of darkness to regulate the timing of reproduction, not all do. Plants that are native to areas between the tropics are mostly daylengthneutral, because daylength doesn’t vary enough to be easily detectable by plants.
