Question

chapter 5: the ecological efficiency in a food chain is 20%. the growth rate of predators is half the growth rate of their prey. if the biomass on trophic level 1 is 400, what is the biomass on trophic level 3.
select one:
a. 160
b. 120
c. 64
d. 30

Explanation:

Step1: Calculate biomass on trophic level 2

The ecological efficiency is 20% or 0.2. Biomass on trophic level 1 is 400. Biomass on trophic level 2 = Biomass on trophic level 1×Ecological efficiency. So, Biomass on trophic level 2 = $400\times0.2=80$.

Step2: Calculate biomass on trophic level 3

Using the same ecological - efficiency formula, Biomass on trophic level 3 = Biomass on trophic level 2×Ecological efficiency. So, Biomass on trophic level 3 = $80\times0.2 = 16$.

Answer:

There is no correct option provided as the calculated answer is 16.