DP Biology (last assessment 2024)
Question 18M.2.HL.TZ2.c
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.2.HL.TZ2.c |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Discuss | Question number | c | Adapted from | N/A |
c.
[Maximum mark: 2]
18M.2.HL.TZ2.c
Leaves were removed from Arabidopsis plants that had been grown in long day and short day conditions and the concentration of starch within them was measured. This was done both at the end of the day (D) and at the end of the night (N) in each of the four stages of development (S1, S2, S3, S4).
Discuss the evidence provided in the bar chart for the hypothesis that plant leaves use up starch reserves for cell respiration during the night.
[2]
Markscheme
a. lower starch levels at end of night in all stages
b. lower starch levels at end of night in both plants grown in short day and long days
c. no evidence that starch is being used for respiration
OR
starch may have been exported/stored in other tissues/example tissue «rather than used in respiration»
