B2 H - Sample set 1 Q8
8 (a) Figure 13 shows a food chain for organisms in a stream.
(i) In the food chain there is 2.1 × 104 J of energy in the biomass of stonefly larvae. 90% of the energy is lost between each trophic level of the food chain.
Calculate the energy value that enters the birds. (2)
Calculate the energy value that enters the birds. (2)
.............................................................. J
(ii) State the impact of this energy loss on the length of the food chain. (1)
(b) A group of students investigated the level of pollution in two different streams, A and B.
Figure 14 shows the student’s results.
(b) A group of students investigated the level of pollution in two different streams, A and B.
Figure 14 shows the student’s results.
Mayfly nymphs, caddis fly lavae and stonefly larvae are indicators of clean water.
(i) Calculate the percentage of organisms in stream A that are clean water indicators.
Give your answer to two significant figures. (2)
(i) Calculate the percentage of organisms in stream A that are clean water indicators.
Give your answer to two significant figures. (2)
..............................................................
(ii) Use the results to explain which stream is more polluted. (2)
The student investigated a third stream, which is very slow flowing and runs through an area where intensive farming methods are used.
Figure 15 shows the thick layer of algae formed on top of this stream.
The student investigated a third stream, which is very slow flowing and runs through an area where intensive farming methods are used.
Figure 15 shows the thick layer of algae formed on top of this stream.
(c) Explain the effect of this algal growth on the organisms in the stream. (4)
(Total for Question 8 = 11 marks)
(Total for Question 8 = 11 marks)