Question

What is the energy available at the $1^{\text{st}}$ trophic level and $3^{\text{rd}}$ trophic level, if $2^{\text{nd}}$ trophic level has $1000\text{kcal}$ of energy?

• A. $1000\text{kcal}$ and $100\text{kcal}$
• B. $1,00,000\text{kcal}$ and $1000\text{kcal}$
• C. $10,000\text{kcal}$ and $1000\text{kcal}$
• D. $100\text{kcal}$ and $10\text{kcal}$

Answer 1

The correct option is B $1,00,000\text{kcal}$ and $1000\text{kcal}$

According to the $10\%$ Law of Energy, only $10\%$ of the energy gets transferred from one trophic level to the next in a food chain.
So if the II trophic level has $10,000\text{kcal}$ then the III trophic level that is frog will have $10\%$ of second trophic level which is ($10000\ast 10\%$)$\text{kcal}=1000\text{kcal}$.
Accordingly, IV trophic level that is the fish will have $10\%$ of third trophic level=($1000\ast 10\%$)$\text{kcal}=100\text{kcal}$. And I trophic level will have $10\%$ more energy than that of second trophic level. i.e. ($10000/10\%$)$\text{kcal}=1,00,000\text{kcal}$.