QUESTION 24 (5 marks)
The diagram is a hypothetical biomass pyramid for a community.
a) Contrast the efficiency of the biomass transfers between each level of the pyramid.
[3 marks]
b) Explain the difference in biomass transfer efficiency identified in Question 24a).
[2 marks]
QCAA guide · typeset solution
QCAA sample response and mark allocation
24a) | Producers à Primary consumers 10% Primary à Secondary consumers 5% The ecosystem shows a drop in efficiency of transfer of biomass from 10% to 5%. | • provides - for producers to primary consumers, 10% [1 mark] - for primary to secondary consumers, 5% [1 mark] • contrasts efficiency [1 mark] |
24b) | As you move through to higher tropic levels, a higher proportion of the energy is lost to respiration and heat, and to decomposers. Overall, a smaller percentage is passed on to the next trophic level. | • states that higher trophic levels lose a higher proportion of their energy due to other processes [1 mark] • states at least one process [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
Compare your working with the guide above.