A student prepared a suspension of isolated chloroplasts and added DCPIP. The suspension was divided into test tubes and placed at different distances from a lamp to vary light intensity. The time taken for the blue colour of DCPIP to disappear (become colourless) was recorded. The results are shown in Table 1.
Table 1
| Distance from lamp (cm) | Time for decolourisation (minutes) |
|---|---|
| 10 | 2.0 |
| 20 | 4.5 |
| 30 | 7.5 |
| 40 | 12.0 |
The student then considered three additional experiments:
(a) At a distance of 10 cm, the CO₂ concentration in the suspension is reduced from 0.04% to 0.01%. Predict the time for decolourisation and explain your prediction.
(b) At a distance of 30 cm, the temperature is increased from 20 °C to 45 °C. Predict the time for decolourisation and explain your prediction.
(c) At a distance of 40 cm, the CO₂ concentration is increased to 0.10%. Predict the effect on decolourisation time and explain why the effect is small.