Energy Transfer Equations

Question 1

Define gross primary production.

Answer 1

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

Question 2

Define net primary production.

Answer 2

The chemical energy store left when energy losses to respiration have been taken into account.

Question 3

The energy from net primary production can be used for which 2 biological processes that occur in plants?

Answer 3

Growth
Reproduction

Question 4

The energy from net primary production is available to use in which 2 trophic levels?

Answer 4

Consumers and decomposers.

Question 5

Which trophic level is the most efficient at transferring their energy for growth?

Answer 5

Secondary/tertiary consumers

Question 6

Give the equation for net primary production.
NPP - Net primary production
GPP - Gross primary production
R - Respiratory losses

Answer 6

NPP = GPP - R

Question 7

Give the equation for net production of consumers.
N - net production of consumers
I - Chemical energy ingested
F - Energy lost in faeces/urine
R - Respiratory energy losses

Answer 7

N = I - (F + R)

Question 8

Give the equation for efficiency.

Answer 8

Energy after transfer/Energy before transfer

Question 8

How does the total biomass at higher trophic levels compare to the total biomass at lower trophic levels?
What does this mean for energy availability through the food chain?

Answer 8

The total biomass is less at higher trophic levels.
This means that the energy available for organisms is less up the food chain.

Question 9

Why is the number of trophic levels in a food chain limited to 4/5?

Answer 9

There isn’t enough energy to support higher trophic levels.