| Date | May 2012 | Marks available | 1 | Reference code | 12M.1.SL.TZ2.11 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Evaluate | Question number | 11 | Adapted from | N/A |
Question
What are the effects of changing carbon dioxide concentration on the rate of photosynthesis?
I. At low and moderate carbon dioxide concentrations, decreases cause the rate of photosynthesis to fall.
II. At high carbon dioxide concentrations, increases do not alter the rate of photosynthesis.
III. At high carbon dioxide concentrations, increases cause the rate of photosynthesis to fall.
A. I only
B. I and II only
C. I and III only
D. III only
Markscheme
B
Examiners report
Feedback on the G2 forms suggested that there was too much information given in the question, and that candidates may have been disadvantaged by this. It was accepted that this type of question was difficult for some candidates, and many were distracted by option A, but the majority did choose the correct response of B, and the question gave good discrimination
