Energy Flows

pyramids of biomass, energy losses, energy in food production, decay, carbon cycle

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  • Created by: Anna
  • Created on: 27-11-11 18:04

Pyramids of Biomass

Biomass - The mass of living material in plants and animals

A Pyramid of Biomass - Represents the mass of the organisms at each stage in a food chain.

It more accurate than a pyramid of numbers because, for example, one bush may have many insects feeding on it but the mass of the bush is far greater than the mass of the insects.


Organism                                   Number                                Biomass (g)

Oak tree (plant)                               1                                        500, 000

Aphids (primary consumer)        10, 000                                      1000

Ladybirds (secondary consumer)  200                                           50

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Biomass cont.

The Sun is the source of energy for all living things on Earth

The energy from the plant is passed on by food chains to animals etc.

The biomass found at each stage of a food chain is less than it was at the previous stage. This is because:

- Not all organisms at one stage are eaten by the stage above

- Some material taken in is passed out as waste, used in respiration (this releases energy for living processes), movement (means less is used for growth) or keeping a constant body temperature

- Some of the light energy from the Sun is reflected off the leaf, goes straight through and the light is only partially usable

Energy cannot be lost, just used to make something else!

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Energy in Food Production

The shorter the food chain the less energy will be lost = therefore more efficient for us to eat plants than it is to eat animals

We can artificially produce meat more effeciently by:

- Preventing the animal from moving so it doesn't waste energy on movement (this is seen as cruelty by many = contreversial)

- Keeping the animal at a warmer temp. so it doesn't use as much energy from food to keep itself at a constant temp.

Free range vs. factory farming

Importing food vs. growing food in the UK

Food Miles: The distance food is transported from producer to consumer

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Detritus feeders (e.g. worms) may start the process of decay by eating dead animals or plants and producing waste materials.

Decay organisms then break down the waste and dead plants and animals

Decay organisms are microoganisms (bacteria and fungi). Decay is faster if it is warm and wet.

All of the materials from the waste and dead organisms are recycled

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The Carbon Cycle

Carbon Dioxide is removed from the environment by green plants for photosynthesis it is also put into the air by respiration by animals and green plants. The carbon from the CO2 is used to make carbohydrates, fats and proteins.

Animals eat green plants and thus build carbon into their bodies.

When animals or plants die, microorganisms release the CO2 into the air

For a plant to decompose, microorganisms digest the materials.

Microorganisms digest materials faster when there is plenty of oxygen

Importance of Carbon: - It is the main constituent of all living cells

                                    - Carbon can form fats, carbs, nucleic acids and proteins

                                    - Component of fuel

                                    - Used in nanotubes for computers

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