Biology 5090 · O Level · Photosynthesis

Photosynthesis — practice question

A student carries out an investigation into how the colour of light affects the rate of photosynthesis. In three separate trials, red, blue, or green light is directed at an aquatic plant. The number of oxygen bubbles given off by the plant is counted. Each trial is repeated three times, and the mean number of bubbles is worked out. Red: $48\,\text{bubbles min}^{-1}$ Blue: $37\,\text{bubbles min}^{-1}$ Green: $12\,\text{bubbles min}^{-1}$ What accounts for these results?

  • AChlorophyll absorbs red and blue light more than green light.
  • BGreen light is absorbed by the water.
  • CMost of the green light is absorbed by the chlorophyll.
  • DRed light is used least in photosynthesis.

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