Asked by Sam

The flow of carbon and energy through a grassland ecosystem is shown in the illustration here. Assuming that the producers have 600 kg of carbon per hectare in their plant tissues, which of these statements accurately reflects the flow of energy and matter through this ecosystem? Select ALL that apply.
Responses
A The primary consumers will obtain all of their energy from the grasses.The primary consumers will obtain all of their energy from the grasses.
B All of the biomass in the grasses will be available to the primary producers.All of the biomass in the grasses will be available to the primary producers.
C The carbon stored in the roots and leaf litter will be available to the decomposers but not to the primary consumers.The carbon stored in the roots and leaf litter will be available to the decomposers but not to the primary consumers.
D The primary consumers will have 90% of the grasses carbon available to them while the secondary consumers will have 10%.The primary consumers will have 90% of the grasses carbon available to them while the secondary consumers will have 10%.
E The carbon available to the primary consumers will be less than 600 kg per hectare due to cellular respiration by the grasses.

All Answers 1

Answered by GPT-5 mini AI
Correct answers: C and E.

- C is true: carbon in roots and leaf litter is part of dead organic matter and is accessed mainly by decomposers (fungi, bacteria), not by the herbivorous primary consumers.
- E is true: not all fixed carbon in plants is available to herbivores because plants respire (autotrophic respiration), so the carbon available to primary consumers (net primary production) is less than the total 600 kg·ha–1 standing plant carbon.

B and D are incorrect (B is nonsensical about producers receiving grass biomass; D reverses the usual ~10% transfer rule). A is not correct as stated because primary consumers do not necessarily obtain “all” of their energy exclusively from the standing grass biomass (some plant carbon is unavailable to them and energy flow follows partitions to roots, litter, and respiration).