Transfer of Biomass Flashcards

All 6 cards in this deck

About what percentage of the incident light energy do producers transfer for photosynthesis?

About 1 %.

Approximately what percentage of the biomass in one trophic level is transferred to the level above?

About 10 %.

Name the ways biomass is lost between one trophic level and the next.

Not all ingested material is absorbed, so some is egested as faeces; absorbed material is lost as waste — carbon dioxide and water in respiration, and water and urea in urine.

What are the steps to calculate the efficiency of biomass transfer between two trophic levels?
e.g. 500 g of grass eaten gives 50 g of rabbit biomass

1. Divide the biomass of the higher level by the biomass of the level below: $50 \div 500 = 0.1$.
2. Multiply by 100 for a percentage: $0.1 \times 100 = 10\%$.

True or false? All the biomass an animal eats becomes new biomass in its body.

False. Much is egested as faeces or lost as carbon dioxide and water from respiration and urea in urine, so only about 10 % becomes new biomass.

Why are there usually fewer organisms at each higher trophic level, and why are food chains short?

Biomass is lost at every transfer, so there is less biomass available to support organisms at higher levels.