Question

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.
a 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.
c 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%.
e the carbon available to the primary consumers will be less than 600 kg per hectare due to cellular respiration by the grasses.

Explanation:

• A: Primary consumers (herbivores) rely on producers like grasses for energy, so this is correct.
• B: Not all grass biomass is available—some is used for grass respiration or becomes litter, so this is incorrect.
• C: Roots/litter are decomposed by decomposers; primary consumers don’t eat dead plant parts, so this is correct.
• D: Energy transfer is ~10% per trophic level, not 90% to primary consumers, so this is incorrect.
• E: Grasses use some carbon for respiration, so less than 600 kg is available to primary consumers, so this is correct.

Answer:

A. The primary consumers will obtain all of their energy from the grasses, C. The carbon stored in the roots and leaf litter will be available to the decomposers but not to the primary consumers, E. The carbon available to the primary consumers will be less than 600 kg per hectare due to cellular respiration by the grasses.