1. 5.1 + 5.2 Pyramids of Biomass WAL: what pyramids of biomass show and how they are useful. The outcomes • Can you interpret and construct a pyramid of biomass in terms of organism populations? • Can you explain what relationship food chains and pyramids of biomass show? • Can you describe what a food chain shows? Starter: Review your understanding of the previous topic.

2. What do we get from food?

3. What do we get from food? Energy!

4. Energy in Food Chains Energy is stored in organisms as chemical energy. When one organism eats another, this energy is passed on.

5. Energy in Food Chains Not all of this energy is passed on, however. Some is lost in other ways; Released in respiration to allow movement and to keep the rabbits body temperature constant. Only a small amount is used for growth – this is passed onto predators. A lot of the chemical energy is passed out as undigested food.

6. Energy in Food Chains Normally, there are fewer organisms as you go along a food chain, because energy is lost at each stage. 10 3 1

7. What is a food chain? A food chain is a diagram which shows the flow of energy from one organism to another as they eat one another.

8. Pyramids of Numbers We can show these stages in a food chain using a pyramid of numbers; (Secondary Consumer) Fox (Primary Consumer) Rabbits Lettuces (Producer) Each level on a pyramid of numbers is called a trophic level.

9. Pyramids of Numbers Pyramids of numbers do not always look like pyramids, however. For example, one rose bush can feed many aphids; (Secondary Consumer) Ladybirds (Primary Consumer) Aphids Rose bush (Producer)

10. Pyramids of Numbers Pyramids of numbers do not always look like pyramids, however. For example, one rose bush can feed many aphids; (Secondary Consumer) Ladybirds (Primary Consumer) Aphids Rose bush (Producer) What would be a better way of showing the flow of energy?

11. Pyramids of Biomass Pyramids of numbers do not take into account the size of the organisms. A better way of showing the transfer of energy is to use a pyramid of biomass. This shows the mass of each organism at each trophic level. Bigger organisms = more energy

12. Pyramids of Biomass A sample of organisms is taken and they are dried out before they are weighed. How wet or dry the weather is can affect the mass of the organisms, so their dry weight is taken to ensure that the measurements of biomass are accurate. (Secondary Consumer) Ladybirds 5g Aphids 10g (Primary Consumer) Rose bush 1000g (Producer)

13. Pyramids of Biomass Pyramids of numbers do not take into account the size of the organisms. A better way of showing the transfer of energy is to use a pyramid of biomass. This shows the mass of each organism at each trophic level. (Secondary Consumer) Ladybirds 5g Aphids 10g (Primary Consumer) Rose bush 1000g (Producer)

14. How to construct a pyramid of biomass Construct a pyramid of biomass for the following food chain. Use the graph paper below where 1 small square will represent 100kg: Grass  Rabbit  Fox 50,000 1,200 500 0.1kg 3kg 5kg

15. How to construct a pyramid of biomass Construct a pyramid of biomass for the following food chain. Use the graph paper below where 1 small square will represent 100kg: Grass  Rabbit  Fox 50,000 1,200 500 0.1kg 3kg 5kg 3,600kg 5000kg 2,500kg

16. How to construct a pyramid of biomass Construct a pyramid of biomass for the following food chain. Use the graph paper below where 1 small square will represent 100kg: Grass  Rabbit  Fox 100 100 2,500kg 100 3,600kg 5000kg 50 squares 36 squares 25 squares Foxes Rabbits Grass