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12 (a) Materials cycle through the environment - OCR Gateway - GCSE Biology Combined Science - Question 12 - 2021 - Paper 1
Question 12
12 (a) Materials cycle through the environment. Complete the sentences about recycled materials. Carbon inside carbohydrates is released back into the atmosphere... show full transcript
Worked Solution & Example Answer:12 (a) Materials cycle through the environment - OCR Gateway - GCSE Biology Combined Science - Question 12 - 2021 - Paper 1
Step 1
Identify which of the bacteria in Fig. 12.1, if present in large amounts, would make the soil poor for plant growth.
Answer
Denitrifying bacteria, if present in large amounts, would make the soil poor for plant growth because they convert nitrates in the soil into nitrogen gas, thus decreasing the availability of essential nutrients for plants.
Step 2
Explain why large amounts of these bacteria would make the soil poor for plant growth.
Answer
Large amounts of denitrifying bacteria would make the soil poor for plant growth as they remove nitrates from the soil. Nitrates are crucial for plant nutrition, and their depletion hinders plant growth and productivity.
Step 3
Step 4
Explain why lines X, Y and Z level out at different rates of photosynthesis.
Answer
Line Y levels out first because the rate becomes limited by both carbon dioxide concentration and temperature. This indicates that even with high light intensity, other factors restrict the rate of photosynthesis.
Line Z levels out second because higher light intensities enable a higher rate until it becomes limited by temperature.
Line X levels out last due to carbon dioxide and temperature not limiting the rate, thus showing that it supports the highest rate of photosynthesis.