Igcse Model Questions Vol1 2023 Biology Question 17

In Lake A, the net primary productivity of the phytoplankton is \(1200\ \text{g C m}^{-2}\text{yr}^{-1}\). Energy is transferred through five trophic levels (including the producers) with an ecological efficiency of 10 % between each successive level. (a) Calculate the total amount of carbon that reaches the top‑carnivore level per square metre per year. (b) If the top‑carnivore population consists of 200 individuals, what is the average carbon content per individual? (c) A second lake, Lake B, has the same primary productivity but an ecological efficiency of 15 % between levels. What is the ratio of carbon reaching the top‑carnivore level in Lake B to that in Lake A? Give your answer to two decimal places.