In a trophic pyramid, if the energy transfer efficiency between trophic levels is $10\%$, how much energy in $\text{kcal}$ will be available to the tertiary consumers if the primary producers have $1,000,000\text{ kcal}$ of energy?

Solution

1. Primary producers are at the first trophic level.
2. Primary consumers (level 2) receive $10\%$ of $1,000,000=100,000\text{ kcal}$.
3. Secondary consumers (level 3) receive $10\%$ of $100,000=10,000\text{ kcal}$.
4. Tertiary consumers (level 4) receive $10\%$ of $10,000=1,000\text{ kcal}$.
5. Hence the answer is (A).