Question

In an ecosystem if the Net Primary Productivity (NPP) of first trophic level is 100x (kcal m^-2)yr^-1, what would be the GPP (Gross Primary Productivity) of the third trophic level of the same ecosystem?

• A. \(\frac {x}{10}\) (kcal m^-2)yr^-1
• B. \(x\) (kcal m^-2)yr^-1
• C. \(10x\) (kcal m^-2)yr^-1
• D. \(\frac {100x}{3x}\) (kcal m^-2)yr^-1

Answer 1

The Correct Option is C

Gross Primary Productivity (GPP) is the total energy captured by producers, while Net Primary Productivity (NPP) is the energy that remains after producers use energy for respiration.

Step 1: Typically, GPP is higher than NPP, as some of the energy is used for respiration.

Step 2: Energy decreases at each trophic level due to losses in respiration and metabolic activities. If NPP at the first trophic level is 100x, then the GPP at the third level is typically around 10x.

Thus, the correct answer is (3) 10x kcal m⁻² yr⁻¹.