1.1. A food chain is shown in Figure 3 below, along with the levels of biomass at each trophic level.

Figure 3

Complete the pyramid of biomass below; the sparrowhawk and blue tit have been completed for you. 

1.2. For the food chain shown in Figure 3, calculate the percentage of the oak tree's biomass that is present in the blue tits. 

1.3. The units of biomass are given in Figure 3 as kg/m². What does the m² part of this unit refer to?

1.4. Give one reason why in a pyramid of biomass, each level is narrower than the level below it.