Biology 9700 · AS & A Level · Testing for biological molecules
Testing for biological molecules — practice question
Lancaster Sound in the Canadian Arctic is a highly productive marine habitat that sustains abundant sea birds and marine mammals. Research in this region has highlighted the role of Arctic cod, Boreogadus saida, in transferring energy to marine birds such as guillemots and fulmars, and to marine mammals such as narwhals and belugas. For many of these animals, Arctic cod is the chief food source, or even the only one. The movement of energy through the food web in Lancaster Sound is shown in Fig. 4.1.
(a)[3]
State the trophic levels occupied by these organisms in the food web shown in Fig. 4.1:
kelp
arrow worms
narwhals.
(b)[4]
The number of polar bears in the Lancaster Sound area is relatively low compared with the numbers of animals that feed on Arctic cod.
Using only the information in Fig. 4.1, explain why the polar bear population is small.
(c)[3]
Many fish species are threatened with extinction because of over-fishing.
Explain the likely consequences of over-fishing of Arctic cod.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Recognising the producer, secondary consumer and tertiary consumer” …