Question

if the secondary consumer level of a trophic pyramid has 1,000 kcal of energy, how much energy is required by the primary consumers (herbivores), to support this pyramid? 17,500 kcal 10,000 kcal 10 kcal

Explanation:

Step1: Recall energy transfer rule

In a trophic pyramid, energy transfer between levels is about 10% (so 90% is lost). So, if secondary consumers (level 3) have energy \( E_{sec} \), primary consumers (level 2) have \( E_{prim} \) where \( E_{sec} = 0.1 \times E_{prim} \).

Step2: Solve for primary consumer energy

We know \( E_{sec} = 1000 \) kcal. Rearranging \( E_{prim}=\frac{E_{sec}}{0.1} \).
Substitute \( E_{sec} = 1000 \): \( E_{prim}=\frac{1000}{0.1}= 10000 \) kcal.

Answer:

10,000 kcal (corresponding to the option with "10,000 kcal")