Question

What is the energy (in $\text{J}$) obtained by the $\text{Tiger}$ in the following food chain, if $1,850\text{J}$ is the net primary production ($\text{NPP}$)?

$\text{Rabbit}\to \text{Jackal}\to \text{Tiger}$

• A. $18.5\text{J}$
• B. $46.25\text{J}$
• C. $4.625\text{J}$
• D. $1.85\text{J}$

Answer 1

The correct option is C $4.625\text{J}$

Given:
Net primary production $=1,850\text{J}$
Rabbit is not a producer in any food chain. So, there must be a producer (mostly likely a plant) that has produced a $\text{NPP}$ of $1,850\text{J}$, of which usually about $75\%$ is utilised in the death and the decay of the producer.

So, $1850(1-\frac{75}{100})=462.5\text{J}$ is available for the primary consumer $\left(\text{Rabbit}\right)$.

Out of this $462.5\text{J}$, only $10\%$ will move onto the next(secondary) consumer $\left(\text{Jackal}\right)$.
$⟹462.5\times \frac{10}{100}=46.25\text{J}$

Out of this $46.25\text{J}$, only $10\%$ will move onto the next(tertiary) consumer $\left(\text{Tiger}\right)$.
$⟹46.25\times \frac{10}{100}=4.625\text{J}$

Therefore, $4.625\text{J}$ is the energy obtained by the $\text{Tiger}$ in the given food chain.