GCSE Required Practical – Biology 1 – Light and Photosynthesis
What’s the point of the practical?
To find out what happens to the rate of photosynthesis when we change the light intensity
Example Apparatus
What may they ask us about?
- Why results may be inaccurate (difficult to count very small bubbles, each bubble counts as ‘1’ no matter how big it is)
- Why should you leave the plant for a few minutes before starting to count bubbles (as it takes time for the plant to adjust to the light/temperature and for photosynthesis to reach the correct rate).
- Heat from the lamp is a source of error, how could you avoid this? (Place a glass screen in front of the beaker so that light gets through but heat doesn’t)
- What are the other limiting factors apart from light? Why will rate of photosynthesis level off, even with maximum light? (The plant also needs enough temperature and CO2)
Photosynthesis: when plants use carbon dioxide and water to make glucose (and oxygen). Happens in the chloroplast and needs light to happen.
Results
- The closer the lamp, the quicker the bubbles are produced (so higher rate of photosynthesis)