Waec Model Questions Vol1 2022 Biology Question 16

In a grassland ecosystem the following energy transfers occur: - Herbivore group A consumes 40 % of the net primary productivity (NPP) and respire 30 % of the energy it ingests. - Herbivore group B consumes the remaining 60 % of NPP and respire 50 % of the energy it ingests. - Carnivores feed on the post‑respiration energy of the herbivores. They take 25 % of the energy remaining after group A's respiration and 15 % of the energy remaining after group B's respiration. Carnivores respire 55 % of the energy they ingest. - The energy that finally reaches the top‑predator level (i.e., after carnivore respiration) is measured as 2 200 kJ m⁻² yr⁻¹. Assuming all plant material consumed by the herbivores originates from the ecosystem's NPP, calculate the NPP (in kJ m⁻² yr⁻¹).