1.1. Figure 2 shows a food chain for organisms in an area of grassland. Also included is the biomass of the organisms at each trophic level.

Figure 2

Draw a pyramid of biomass for the food chain in Figure 2 on Figure 3.

You should:

• use a suitable scale

• label the x-axis

• label each trophic level

Figure 3

1.2. Biomass is a measure of the mass of a number of organisms, so a scientist might be tempted to measure biomass in the units of mass, kilograms (kg). However, the unit used in the food chain shown in Figure 2 is kg/m².

Explain why. 

1.3. Some units of biomass are expressed with a consideration of time.

For example, one such unit is kg m^-2 yr^-1, which stands for kilograms per square metre per year. 

Suggest a reason why a time consideration is given to the measurement of biomass. 

1.4. Calculate the percentage efficiency of the food chain shown in Figure 2.

Give your answer to 2 significant figures. 

1.5. Explain why a pyramid of biomass often only has a narrow line to depict the apex predator, rather than rectangular box.