Question

The following scenario is the basis for questions 1 through 5. Assume you measured the energy levels in a plant-caterpillar ecosystem (g C m-2 yr-1). Net primary productivity (NPP) was assessed to be 600 g C m-2 yr-1, whereas gross primary productivity (GPP) was measured to be 1500 g C m-2 yr-1. You estimate that the caterpillars absorb 80 g C m-2 yr-1 of the NPP (the remainder being left unfinished). Caterpillars absorb 55 g C m-2 yr-1 of the 80 g C m-2 yr-1 they ingest (regurgitating or excreting the rest). Ultimately, the caterpillars use 20 g C m-2 yr-1 of the absorbed quantity for development and reproduction.

1. What is the estimated amount that the caterpillars respire?

A. 55 - 20 = 35 g C m-2 yr-1

B. 600 - 20 = 580 g C m-2 yr-1

C. 55 + 20 = 75 g C m-2 yr-1

D. 80 - 55 = 25 g C m-2 yr-1




2. What is the net production efficiency of the caterpillars?

A. 20/1500 = 0.0133 = 1.33%

B. 20/600 = 0.0333 = 3.33%

C. 20/55 = 0.3636 = 36.36%

D. 55/80 = 0.6875 = 68.75%




3. What is the ecological efficiency of this simple trophic system?

A. 20/1500 = 0.0133 = 1.33%

B. 20/600 = 0.0333 = 3.33%

C. 80/600 = 0.1333 = 13.33%

D. 20/80 = 0.2500 = 25.00%

Answer 1

The estimated amount that the caterpillars respire is 35 g C m-2 yr-1. The net production efficiency of the caterpillars is 3.33%. The ecological efficiency of this simple trophic system is 25.00%.

Step-by-step explanation:

The estimated amount that the caterpillars respire is 35 g C m-2 yr-1. This can be calculated by subtracting the amount of carbon absorbed by the caterpillars for development and reproduction (20 g C m-2 yr-1) from the amount they ingest (55 g C m-2 yr-1).

The net production efficiency of the caterpillars is 3.33%. This can be calculated by dividing the amount of carbon used for development and reproduction (20 g C m-2 yr-1) by the ingested amount (600 g C m-2 yr-1) and multiplying by 100.

The ecological efficiency of this simple trophic system is 25.00%. This can be calculated by dividing the absorbed quantity used for development and reproduction (20 g C m-2 yr-1) by the net primary productivity (NPP) (80 g C m-2 yr-1) and multiplying by 100.