1. Energy and biomass in food chains
Energy in biomass

2. Summary of Specification Content
The Sun is the source of energy for most communities; photosynthesis.
Pyramids of biomass.

3. Learning Outcomes
Construct and interpret pyramids of biomass.

4. Food Chains Food chains are one way of showing how organisms interact.
Grass Rabbit  Fox
The arrows represent the transfer of energy between organisms.

5. Food Chains Plants are producers because they make their own food
Animals are consumers because they eat food to obtain energy.

6. Consumers and Decomposers
There are 3 types of consumer
Herbivores eat plants
Carnivores eat other animals
Omnivores eat plants and animals
Organisms that breakdown dead plants and animals are called decomposers
e.g. fungi and bacteria

7. Producer  primary  secondary  tertiary consumer consumer consumer
Each feeding level is known as a trophic level

8. Energy in the Ecosystem
The sun is the main source of energy for food chains
Photosynthetic organisms capture a small percentage of the solar energy which reaches them and convert this into chemical energy.
This chemical energy is then available to other organisms.

9. Light energy available to the plant
Of the 100% solar energy reaching the Earth only some is trapped by chlorophyll
What happens to the rest?
Reflected by clouds or dust in the air
Reflected by plants
Does not fall on leaves
Wrong wavelength for chlorophyll to trap
Pass through leaves

10. Energy Flow through an ecosystem
Energy is transferred from one organism to another.
This is shown in food chains and food webs
Energy given out by organisms is lost to the environment.

11. Food Webs
If food chains in a habitat are linked, they form a FOOD WEB.

12. Food web for a single tree

13. Changing Food Webs Look at the two examples of ecosystems given.
For each question give a suggestion of what might happen to the populations of organisms and explain why you think this.

14. Changing food webs

15. Pupil Activity
Copy out two food chains from the food web both must finish with the top carnivore
One food chain containing 4 organisms
One food chain containing 5 organism
What would happen to the number of
Frogs if all the slugs were removed
Frogs if the minnows were removed
Insect larvae if the slugs were removed
You must give an explanation for your explanation.

16. Changing food webs

17. Food Webs
Food webs are easily unbalanced if one population of organisms in the web disappears due to:
Over-predation or hunting
Disease
Pollution
Use of pesticides
Lack of food
emigration