Question 21N.1.SL.TZ0.12
| Date | November 2021 | Marks available | [Maximum mark: 1] | Reference code | 21N.1.SL.TZ0.12 |
| Level | SL | Paper | 1 | Time zone | TZ0 |
| Command term | Question number | 12 | Adapted from | N/A |
A respirometer is used to measure the oxygen consumption of germinating seeds. The distance that the oil drop moves is measured at 15-minute intervals.
[Source: © The Royal Society of Biology.]
What is the function of chemical X?
A. Absorbs carbon dioxide so the oxygen released by the seeds can be measured
B. Absorbs carbon dioxide so the oxygen absorbed by the seeds can be measured
C. Absorbs oxygen so the carbon dioxide released by the seeds can be measured
D. Absorbs oxygen so the carbon dioxide absorbed by the seeds can be measured
[1]
B
The discrimination index for this question was not as high as expected, probably because some candidates thought that a germinating seed must release oxygen, rather than absorb it. The diagram showed seeds without any leaves developed, so we can assume that respiration rates would have exceeded photosynthesis.
