Topic 5: Energy Transfers in and Between Organisms

Question 1

What is the definition of Net Primary Productivity (NPP)?

Answer 1

NPP is the chemical energy available to plants for growth and reproduction, after respiratory losses (R) have been subtracted from Gross Primary Productivity (GPP).

NPP = GPP − R

Question 2

What is Gross Primary Productivity (GPP)?

Answer 2

GPP is the total chemical energy converted from light energy by plants in a given area and time.

Question 3

Why is NPP important in ecosystems?

Answer 3

NPP represents the energy available to herbivores and other consumers in the food chain

Question 4

What factors affect NPP?

Answer 4

Light intensity, temperature, water availability, nutrient levels, and the plant species present.

Question 5

How can farming practices increase NPP?

Answer 5

By reducing energy losses (e.g. using fertilisers, controlling pests), and optimising growth conditions (e.g. irrigation, temperature control).