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Pyramids Of Number & Biomass

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Presentation on theme: "Pyramids Of Number & Biomass"— Presentation transcript:

1 Pyramids Of Number & Biomass
D. Crowley, 2008

2 Pyramids Of Number & Biomass
Thursday, April 13, 2017 Pyramids Of Number & Biomass To understand pyramids of number and biomass

3 Big Mac Where does the energy in a Big Mac come from?
There is no energy in a big Mac – that is why they are bad for you It comes from the sugar in the burger sauce It comes from the cows that make the burger It comes from the green parts because they are healthier It comes from the sun

4 Big Mac All the energy within our food originates from the sun – transferred through food chains... It comes from the sun

5 Food Chains & Webs A food chain shows what eats what in a particular habitat - the arrow points in the direction of the energy flow, e.g. Here the grass (producer) is eaten by the vole (primary consumer) which is eaten by the barn owl (secondary consumer) Energy is passed along the food chain, so the number of organisms decreases from one trophic level to the next (as energy is lost)

6 Population The population of each organism in a food chain can be shown in a sort of bar chart called a pyramid of numbers The more organisms there are, the wider the bar. The producer in the food chain always goes at the bottom of the pyramid of numbers E.g. clover  snail  thrush  hawk

7 Pyramid Of Number Pyramids of number show how many organisms there are in a habitat A pyramid of number for the food chain below might look like this: - If there were 200 grass plants; 25 voles; and 1 barn owl

8 Pyramid Of Number Pyramids of number show how many organisms there are in a habitat However they may not always look like classical pyramids: - Here there are much more caterpillars than there are oak trees which is why the pyramid is oddly shaped.

9 Pyramid Of Biomass Biomass means the amount of biological material
The pyramid shows the amount of biological material at each level This means the oak tree has the most biological material whilst the sparrow hawk has the least

10 Pyramids Complete the pyramids worksheet


12 grass  grasshopper  frog  grass snake
Questions 1. Draw out, and explain why this pyramid looks a funny shape: - Look at the food chain below: - grass  grasshopper  frog  grass snake 100’ 2. Draw a pyramid of numbers for the food chain 3. Write down the names of: the top predator; the producer; the consumers; the primary consumer; the tertiary consumer; the herbivores; the carnivores Fleas Rabbits Lettuce plants

13 Questions 1. Pyramid of number: many fleas can feed of just one rabbit
2. 3. Top predator – grass snakes; Producer - grass; Consumers – grasshoppers, frogs, grass snakes; Primary consumer - grasshoppers; Tertiary consumer – grass snakes; Herbivores - grasshoppers; Carnivores – frogs, grass snakes Fleas Rabbits Lettuce plants Grass snake Frog Grasshoppers Grass

14 Fox & Sun Explain as fully as you can why a fox is reliant on the Sun...

15 Sun → Grass → Rabbit → Fox
Fox & Sun Producers (e.g. grass) grow via photosynthesis, getting their energy from the Sun This energy is used to allow the producer to grow (increase in biomass), eventually being passed on to consumers (e.g. a rabbit) when they eat it When a fox eats the consumer energy is again passed on, so completing the energy chain from Sun to producer to consumer to secondary consumer (fox) Sun → Grass → Rabbit → Fox

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