Energy transfer between trophic levelsAQA A-Level Biology: Mind map

Exam questions on Energy transfer between trophic levels

1. A dairy cow grazes on a pasture. During one day, the chemical energy store in the grass she ingests is 250 MJ. She loses 90 MJ in faeces and urine and releases 110 MJ in respiration.
   Calculate the net production of the cow in MJ per day and express it as a percentage of the energy she ingests.2 marks
2. An ecologist studies a food chain in an estuary. The net primary production of the phytoplankton is 20 000 kJ m⁻² year⁻¹. The net production of the zooplankton that feed on them is 2 400 kJ m⁻² year⁻¹, and the net production of the small fish that feed on the zooplankton is 360 kJ m⁻² year⁻¹.
   Calculate the efficiency of energy transfer from the zooplankton to the small fish.2 marks
3. In an oak woodland the net primary production of the trees is 14 000 kJ m⁻² year⁻¹. Herbivorous insects consume 1 400 kJ m⁻² year⁻¹ of this. Most of the rest falls to the ground as leaf litter and dead wood, and a small amount is stored as new wood in the living trees.
   Calculate the percentage of the trees' net primary production that is consumed by herbivorous insects, and suggest two reasons why most of the net primary production is not consumed by them.3 marks