1. We don’t store all the energy from the food we eat.
Energy expenditure:
Only 10% of the energy is stored for growth and development of the individual organism. The rest is used to carry out body functions, such as digestion, eliminated in feces, or is lost as heat.

2. 100 kJ
10 kJ
1 kJ

3. This diagram shows how much energy is transferred through a food chain:

5. Pyramid of Numbers
Shows the population of organisms at each trophic level of the food chain.
The more organisms there are, the wider the bar.
Producers are always placed at the bottom.

6. Less organisms are found higher up in the food chain as a result of less energy being available at these levels.

7. What is this Pyramid of Numbers telling us?
Is this an accurate representation of energy flow?

8. What is this Pyramid of Numbers telling us?
Is this an accurate representation of energy flow?

9. Pyramid of Biomass
Shows the dry mass of organisms at each trophic level of the food chain.
Accounts for a more accurate representation of the energy flow through a food chain
The larger the biomass, the more body tissues present to store energy.

10. Ideal vs Real

11. Discussion Question (discuss with people at your tables)
Why could you feed more people if everyone became a vegetarian??