CAIE A Level Biology 9700 · Photosynthesis
A student investigated the effect of light intensity on the rate of photosynthesis of an aquatic plant (Elodea) at two different temperatures. The oxygen evolution (mm³ min⁻¹) was measured. The results are shown in the table below.
| Light intensity (arbitrary units) | Rate of oxygen evolution at 15°C (mm³ min⁻¹) | Rate of oxygen evolution at 25°C (mm³ min⁻¹) |
|---|---|---|
| 0 | 0 | 0 |
| 100 | 10 | 10 |
| 200 | 15 | 20 |
| 300 | 16 | 28 |
Explain the pattern of results, with reference to limiting factors.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.