Predict5 marksStandard
A student investigates the effect of light intensity and carbon dioxide concentration on the rate of photosynthesis in the aquatic plant Elodea. They place cuttings of Elodea in beakers of water at 20 °C and count the number of oxygen bubbles released per minute. They vary the distance of a lamp from the beaker to change light intensity, and they add sodium hydrogencarbonate (NaHCO₃) to the water to provide different carbon dioxide concentrations. The results are shown in the table.
| Light intensity (arbitrary units) | Bubble count per minute at low CO₂ (0.05% NaHCO₃) | Bubble count per minute at high CO₂ (0.20% NaHCO₃) |
|---|---|---|
| 10 | 8 | 18 |
| 20 | 12 | 30 |
| 30 | 14 | 35 |
| 40 | 14 | 38 |
| 50 | 14 | 40 |
Predict which factor is limiting the rate of photosynthesis at a light intensity of 30 arbitrary units in the low CO₂ condition. Use the data to support your prediction.