The graph shows the effects of changing the temperature, light intensity and carbon dioxide concentration on the growth of lettuce plants.
400
4% CO,. 25°C
300
4% CO., 15°C
Mean mass
of lettuce
plants after
21 days
200
in grams
100
0.03% CO., 25°C
0.03% CO 15°C
0
2
8
10
4
6
Light intensity in arbitrary units
(a)
Describe and explain the effect of increasing light intensity on the mean mass of
lettuce plants at 4% carbon dioxide and 15°C