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Photosynthesis is an important chemical reaction in plants - AQA - GCSE Biology Combined Science - Question 4 - 2022 - Paper 1
Question 4
Photosynthesis is an important chemical reaction in plants. 04.1 Why is light needed for photosynthesis? _________________________________________________ 04.2 Wh... show full transcript
Worked Solution & Example Answer:Photosynthesis is an important chemical reaction in plants - AQA - GCSE Biology Combined Science - Question 4 - 2022 - Paper 1
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04.3 Describe how the student should make accurate measurements to obtain valid results for the rate of photosynthesis.
Answer
To obtain valid measurements for the rate of photosynthesis, the student should:
- Allow the pondweed to equilibrate in the light for a few minutes before taking measurements.
- Use the same concentration of sodium hydrogen carbonate solution for each color of light.
- Measure the volume of oxygen produced accurately, using a gas syringe or a measuring cylinder.
- Ensure that variables such as temperature and the distance of the light source remain constant during the experiment.
- Repeat the measurements multiple times and calculate the mean to ensure reliability.
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04.4 Why are the results for the two investigations presented differently?
Answer
The results are presented differently because the independent variable in the student's investigation is the color of light, which is categorical, whereas the independent variable in the scientist’s investigation is the wavelength of light, which is a continuous variable. This contrasts in how the data is represented graphically, with one being discrete and the other being continuous.
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