People eat fish caught in the North Sea - AQA - GCSE Biology - Question 3 - 2021 - Paper 1
Question 3
People eat fish caught in the North Sea.
Figure 4 shows a food chain.
Algae → Small animals → Herring → Human
The algae make glucose by photosynthesis.
Which two... show full transcript
Worked Solution & Example Answer:People eat fish caught in the North Sea - AQA - GCSE Biology - Question 3 - 2021 - Paper 1
Step 1
Which two substances do the algae need for photosynthesis?
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Answer
The two substances that algae need for photosynthesis are carbon dioxide and water. These two compounds are vital for the process where algae convert light energy into chemical energy.
Step 2
What is the source of energy for photosynthesis?
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Answer
The source of energy for photosynthesis is light. This energy is captured and used by the algae to convert carbon dioxide and water into glucose.
Step 3
Which pyramid of biomass is correct for the food chain shown in Figure 4?
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Answer
The correct pyramid of biomass for the food chain shown in Figure 4 is the one that illustrates a decreasing biomass as you move up the chain, reflecting the energy transfer inefficiencies typically observed in food chains.
Step 4
Calculate the percentage decrease in the biomass of adult herring between 1960 and 1970.
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Answer
To calculate the percentage decrease, apply the formula:
Describe the change in biomass of adult herring from 1977 to 1990.
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Answer
From 1977 to 1990, there was an increase in the biomass of adult herring. This is indicative of successful conservation efforts as laws aimed at controlling fishing practices were implemented.
Step 6
Explain how the control of mesh size of fishing nets has helped to conserve stocks of herring.
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Answer
The control of mesh size in fishing nets helps to conserve stocks of herring by allowing smaller, younger fish to escape and survive. This practice enhances the reproductive potential of the herring population, ensuring that those fish can reach maturity and contribute to the population growth.
