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... 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?
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Answer
The correct completion of the photosynthesis equation is 'water' for the reactant and 'oxygen' for the product. Therefore, the answer is C: water + carbon dioxide → glucose + oxygen.
Step 2
State three variables that should be kept constant to improve the results.
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Answer
Three variables that should be kept constant include:
The type of plant used, as different plants may have varying rates of photosynthesis.
The amount of carbon dioxide available, ensuring it is constant throughout the experiments.
The temperature of the water, to prevent temperature fluctuations affecting the results.
Step 3
Give one improvement the scientist could make to reduce the effect of this increase in temperature.
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Answer
One improvement could be to use a water bath to maintain a steady temperature of the water, minimizing the effect of heat from the lamp.
Step 4
Calculate the mean result for a distance of 20cm.
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Answer
To calculate the mean result for a distance of 20cm from the given test results in Figure 2:
Test 1: 23
Test 2: 24
Test 3: 22
Mean = (23 + 24 + 22) / 3 = 23.
Thus, the mean result for 20cm is 23 bubbles counted.
Step 5
State how the scientist could deal with this anomaly.
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Answer
To deal with the anomaly observed in test 2 at 10cm, the scientist could repeat the experiment for that specific case. If the anomaly persists, it may be excluded from the final results to ensure the overall accuracy of the investigation.
