Question

According to Lindemann \[10\% \] law, only \[10\% \] energy is transferred to the next trophic level. If the plants produce \[100\] units of energy, the amount of energy at the level of secondary consumers would be?
 A.\[1\] unit
B.\[25\] unit
C.\[50\] unit
D.\[75\] unit
 E.\[100\] unit

Answer 1

Hint: A scientist ‘Lindmann’ introduced a law regarding the transfer of energy from one trophic level to the next in the food chain. According to his laws, only the \[10\% \] of the energy produced at a particular trophic level is passed to the next trophic level. The other \[90\% \] is lost in respiration and digestion.

Complete answer:
So, to solve the question related to the energy transfer according to the ‘ Lindmann ’s law’ , always keep in mind the sequence of trophic levels and of which trophic level energy is asked in the question.
So let’s proceed with our given question.
In the question they are saying that, the total energy produced by the plants i.e. the producers are \[100\] unit of energy, so according to Lindemann law, only \[10\% \] of this would be transferred to the next level i.e. to the primary consumers.
So let’s calculate it first:
Hence, energy at the primary consumer level will be-
 \[\begin{gathered}
   = 10\% {\text{ of }}100 \\
   = \dfrac{{10}}{{100}} \times 100 \\
   = 10{\text{ unit}} \\
\end{gathered} \]
Now, \[10\% \] of this energy would be transferred to the secondary consumer level. So let’s calculate the total energy present at the secondary consumer level will be:
\[\begin{gathered}
   = 10\% {\text{ of }}10 \\
   = \dfrac{{10}}{{100}} \times 10 \\
   = 1{\text{ unit}} \\
\end{gathered} \]
Hence, their energy present at the secondary consumer level is \[1{\text{ unit}}\].

Therefore, the correct answer is option ‘A ‘i.e. \[1{\text{ unit}}\].

Note:
Always remember to keep in mind the correct order of trophic levels while estimating the total energy at a particular trophic level. The correct order or sequence of trophic level is primary producer \[ \to \] primary consumer \[ \to \] secondary consumer. Here, let’s take an example of a food chain: if the primary producer is a plant, then the primary consumer will be deer and the secondary consumer will be lion.