Gce Model Questions Vol1 2022 Biology Question 50

Two freshwater lakes, A and B, differ in their net primary productivity (NPP) and the proportion of that productivity lost before it can be consumed. Lake A: NPP = \(800\ \text{g C m}^{-2}\text{yr}^{-1}\); 10 % lost to respiration, 20 % lost as non‑consumable detritus; herbivores convert consumed plant material to biomass with an efficiency of 15 %; carnivores convert herbivore biomass to their own with 12 % efficiency; top predators convert carnivore biomass with 8 % efficiency. Lake B: NPP = \(1200\ \text{g C m}^{-2}\text{yr}^{-1}\); 15 % lost to respiration, 25 % lost as detritus; herbivore efficiency = 10 %; carnivore efficiency = 10 %; top‑predator efficiency = 5 %. (a) Calculate the biomass (in \(\text{g C m}^{-2}\text{yr}^{-1}\)) that appears at each trophic level (herbivore, carnivore, top predator) for both lakes. (b) Which lake supports the greater top‑predator biomass? Provide the numerical values that justify your answer.