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Plants need light for photosynthesis - Edexcel - GCSE Biology Combined Science - Question 1 - 2016 - Paper 1
Question 1
Plants need light for photosynthesis. Part of the photosynthesis equation is shown below. -------------- + carbon dioxide → glucose + -------------- (a) Which of t... show full transcript
Worked Solution & Example Answer:Plants need light for photosynthesis - Edexcel - GCSE Biology Combined Science - Question 1 - 2016 - Paper 1
Step 1
Which of the following would complete the photosynthesis equation?
Answer
The correct completion of the photosynthesis equation involves identifying the reactants and products of the process. The equation typically starts with water and carbon dioxide. Therefore, the correct answer is:
C. water → oxygen
This indicates the production of oxygen as a byproduct of photosynthesis alongside glucose.
Step 2
State three variables that should be kept constant to improve the results.
Answer
To improve the reliability of the investigation, the following variables should be kept constant:
- Temperature - to prevent temperature fluctuations from affecting the rate of photosynthesis.
- Volume of water in the test tube - ensuring a consistent supply of water for the plants.
- Type of plant - using the same species to ensure uniformity in photosynthetic response.
Step 3
Give one improvement the scientist could make to reduce the effect of this increase in temperature.
Answer
One improvement the scientist could make is to use a thermometer to monitor the water temperature and ensure it remains consistent. Additionally, placing the lamp further away or using a cooling fan could help reduce the temperature increase during the experiment.
Step 4
Calculate the mean result for a distance of 20cm.
Answer
To calculate the mean number of bubbles counted for a distance of 20cm, use the results from the table:
- Test 1: 23
- Test 2: 24
- Test 3: 22
First, add the results:
Next, divide by the number of tests: ext{Mean} = rac{69}{3} = 23
Thus, the mean result for 20cm is 23 bubbles.
Step 5
State how the scientist could deal with this anomaly.
Answer
To address the anomaly in the number of bubbles counted for test 2 at 10cm, the scientist could:
- Repeat the test to verify the results. If the anomaly persists, it may be disregarded during analysis, or additional data could be gathered under controlled conditions.