Food Chain Energy Calculation

Understanding Trophic Levels and Efficiency

In an ecosystem, energy flows through different trophic levels. Producers form the first level, followed by primary consumers (second level), secondary consumers (third level), and tertiary consumers (fourth level). The commonly accepted rule is that only 10% of the energy from one trophic level is transferred to the next. This is known as the 10% rule.

• Trophic Level 1: Producers
• Trophic Level 2: Primary Consumers
• Trophic Level 3: Secondary Consumers
• Trophic Level 4: Tertiary Consumers

Calculating Energy Transfer from Second to Fourth Level

The question asks for the percentage of energy transferred from the second trophic level to the fourth trophic level.

Let the energy available at the second trophic level be $E_2$.

Energy transferred to the third trophic level ($E_3$) is 10% of $E_2$:

$E_3 = 10\% \times E_2 = 0.1 \times E_2$

Energy transferred to the fourth trophic level ($E_4$) is 10% of the energy at the third trophic level ($E_3$):

$E_4 = 10\% \times E_3 = 0.1 \times E_3$

Substitute the expression for $E_3$ into the equation for $E_4$:

$E_4 = 0.1 \times (0.1 \times E_2)$

$E_4 = 0.01 \times E_2$

To find the percentage of energy transferred from the second level to the fourth level, we calculate the ratio of $E_4$ to $E_2$ and express it as a percentage:

Percentage Transfer = $ \frac{E_4}{E_2} \times 100\% $

Substitute the value of $E_4$:

Percentage Transfer = $ \frac{0.01 \times E_2}{E_2} \times 100\% $

Percentage Transfer = $ 0.01 \times 100\% $

Percentage Transfer = $ 1\% $

The calculated percentage is 1%. This result falls within the range specified in the correct answer (0.99 to 1.01).