Biomass and productivityAQA A-Level Biology: Mind map

Exam questions on Biomass and productivity

1. An ecologist estimates the biomass of a meadow. She cuts all the vegetation from several 1.0 m² quadrats, dries it in an oven at 80 °C and reweighs it at intervals until the mass stops changing. The mean dry mass of vegetation per quadrat is 240 g.
   The ecologist's quadrats are 1.0 m² and 1 ha = 10 000 m². Calculate the mean dry mass of the meadow vegetation in kg ha⁻¹.2 marks
2. A student measures the chemical energy stored in dried meadow plants using calorimetry. She burns 0.50 g of dried, ground plant material beneath a boiling tube containing 100 g of water. The temperature of the water rises by 19.0 °C. The specific heat capacity of water is 4.2 J g⁻¹ °C⁻¹.
   Calculate the energy released per gram of dried plant material, in kJ g⁻¹.2 marks
3. A conifer plantation of area 1 ha has a gross primary production (GPP) of 21 000 kJ m⁻² year⁻¹. The trees lose 8 400 kJ m⁻² year⁻¹ to the environment as a result of respiration. A second plantation (B) of the same area has the same GPP but a net primary production (NPP) of 15 750 kJ m⁻² year⁻¹.
   Calculate the net primary production (NPP) of the first plantation in kJ m⁻² year⁻¹, and state what this energy is available for.3 marks