Production and Productivity

Question 1

What is gross primary production (GPP)?

Answer 1

the total quantity of chemical energy stored in plant biomass, in a given area or volume.

Question 2

What is net primary production (NPP)?

Answer 2

the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account

Question 3

What is the NPP available for use as?

Answer 3

is available for plant

growth and reproduction. It is also available for consumers in the food chain such as herbivores and decomposers

Question 4

What is net production (N)?

Answer 4

the total chemical energy consumers store after energy losses to faeces, urine and respiration have been taken away from the chemical energy store of the ingested plant food

Question 5

What is primary and secondary productivity?

Answer 5

the rate of primary or

secondary production, respectively. It is measured as biomass in a given area in a given time e.g. kJ ha–1 year–1

Question 6

The percentage efficiency of energy transfer from one trophic level to another can be calculated as…

Answer 6

the energy available after transfer/ the energy available before transfer X100

Question 7

Name farming practices that increase the effciency of energy transfer to increase yields

Answer 7

Reducing respiratory loses in a human food chain e.g. reduce movement of animals
Simplifying food chains to reduce energy loss to non-human food chains e.g. killing weeds and pest using herbicides and insecticides