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Two students investigate photosynthesis - OCR Gateway - GCSE Biology - Question 18 - 2020 - Paper 1
Question 18
Two students investigate photosynthesis. Look at the notes from their investigation. Aim of the experiment To use pondweed to see how light intensity affects the ra... show full transcript
Worked Solution & Example Answer:Two students investigate photosynthesis - OCR Gateway - GCSE Biology - Question 18 - 2020 - Paper 1
Step 1
Step 2
Explain why counting the number of bubbles will not give an accurate measure of the rate of photosynthesis.
Answer
Counting the number of bubbles may not give an accurate measure of the rate of photosynthesis because:
- Bubbles produced can be of different sizes, which means that some may contain more or less oxygen gas than others.
- Some bubbles may also be missed or not counted accurately, leading to inconsistent results.
- Factors such as temperature and ambient light may also affect bubble production, leading to variability that is unrelated to the actual rate of photosynthesis.
Step 3
Describe how the students could develop their investigation to improve the accuracy of their results.
Answer
To improve the accuracy of their results, the students could:
- Use a gas syringe instead of counting bubbles, which would allow for a more precise measurement of the volume of oxygen produced.
- Ensure that the size of the pondweed and its surface area for photosynthesis is consistent for all trials.
- Control additional variables such as water temperature, pH levels, and the concentration of carbon dioxide to isolate the effect of light intensity.
- Repeat the experiment multiple times to obtain average values and reduce the impact of anomalous results.