GCSE Biology Required Practical: Factors Affecting the Rate of Photosynthesis
Key Stage 4
Meaning
Investigate the effects of light intensity on the rate of photosynthesis.
Method
- Independent Variable - Distance between the light source and plant.
- Dependent Variable - Number of bubbles produced by the plant.
- Control Variables - Brightness of the light. Frequencies that the light emits. Ensure no other light source than the one used in the experiment.
- Fill a boiling tube with 0.2% solution of sodium hydrogen carbonate.
- Place a length of pond weed in the boiling tube with the cut end at the top.
- Use a metre rule with zero at the light source to fix the boiling tube at 10cm from the light source.
- Use a timer to count the number of bubbles produced by the pond weed.
- Repeat steps three and four 6 times increasing the distance by 10cm each time.