DP Biology (first assessment 2025)
Question 23M.2.SL.TZ1.1d
Date | May 2023 | Marks available | [Maximum mark: 1] | Reference code | 23M.2.SL.TZ1.1d |
Level | SL | Paper | 2 | Time zone | TZ1 |
Command term | State | Question number | d | Adapted from | N/A |
d.
[Maximum mark: 1]
23M.2.SL.TZ1.1d
(d)
The data in the graph show a long-term trend in global LAI.
(d.i)
State the trend.
[1]
Markscheme
Increase/increasing/upwards/rising (trend);
Reject ‘positive’, ‘positive trend’ and ‘positive correlation’
Accept linear increase.

(d.ii)
Global ecosystem modelling suggests that most of the change in LAI is due to increases in atmospheric carbon dioxide. Explain how rising atmospheric carbon dioxide (CO2) concentration could cause the observed change in LAI.
Markscheme
- more photosynthesis (with higher carbon dioxide concentration);
- more plant growth/more (plant) biomass/more leaves/more plants;
If the answer focuses on greenhouse effect or global warming, do not award mpa, but mpb can be awarded if one of the alternatives is included in the answer.