Igcse Model Questions Vol1 2018 Biology Question 34

In a lake ecosystem the following data are given:\n\n- Net primary productivity of phytoplankton: 800 kg yr\(^{-1}\).\n- Zooplankton convert 10 % of this productivity into their own biomass each year.\n- Carnivorous fish consume 20 % of the zooplankton biomass annually and convert 25 % of the consumed biomass into fish biomass.\n- A top‑predator fish species feeds exclusively on the carnivorous fish and converts 30 % of the consumed fish biomass into its own biomass.\n\n(a) Calculate the annual biomass production (kg yr\(^{-1}\)) of the carnivorous fish before the introduction of the top predator.\n\n(b) Assuming the top predator can only rely on the newly produced biomass of the carnivorous fish each year, what is the maximum sustainable increase in the top‑predator population (kg yr\(^{-1}\)) that will not reduce the carnivorous‑fish biomass production below the value found in part (a)?