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AQA · GCSE · Biology · Higher

Biomass pyramid construction

Q07.2 3 marks

Another farmer produced 4200 kg of maize seeds in a field. The farmer fed the maize to 1000 chickens. At full size, the mean mass of one chicken was 2.2 kg. Complete Figure 11 to show a pyramid of biomass for the food chain from the maize seeds to 1000 chickens.

  • label the x-axis
  • use a suitable scale

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Marking points

  1. 1 Uses a suitable x-axis scale symmetric about zero.
  2. 2 Labels the x-axis in kg and the bars maize and chickens.
  3. 3 Plots maize biomass 4200 kg and chicken biomass 2200 kg accurately.

Full-mark answer

Chicken biomass = 1000 × 2.2 = 2200 kg. On Figure 11, use a symmetric scale about 0, label the x-axis 'Biomass in kg', and draw a maize bar to ±4200 and a chickens bar to ±2200, with both bars labelled.

Why this answer loses marks

Draw a normal upright pyramid with equal-width bars.

This misses the calculated consumer total, the centred scale and bar widths proportional to each biomass.