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EcologyHigherecologybiomasstrophic levels

AQA GCSE · Question 02.2 · Ecology

The peat bog is a stable community. The moss produces biomass at a rate of 340 g/m²/year. What is the approximate biomass of the moss that becomes biomass in primary consumers?

Answer options:

A.

0.34 g/m²/year

B.

3.4 g/m²/year

C.

34 g/m²/year

D.

340 g/m²/year

How to approach this question

Recall the general rule for the percentage of biomass transferred from one trophic level to the next. Apply this percentage to the given biomass production rate of the moss.

Full Answer

C.34 g/m²/year✓ Correct
In a food chain, only a fraction of the energy from one trophic level is incorporated into the biomass of the next. A general rule of thumb is that this transfer is about 10% efficient. The rest of the energy is lost, mainly through metabolic processes like respiration, or is unavailable (e.g., inedible parts). In this case, the moss is the producer with a biomass of 340 g/m²/year. The primary consumers will incorporate approximately 10% of this into their own biomass. Calculation: 10% of 340 = 0.10 * 340 = 34 g/m²/year.

Common mistakes

✗ Forgetting the 10% rule and choosing a random value. ✗ Miscalculating the percentage (e.g., calculating 1% instead of 10%).

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