Biology - Energy in Biomass

These cards are for AQA revision and have four sub - sub topics which are:

1. Pyramids of Biomass     2. Energy Transfers     3. Decay Process     4. The Carbon Cycle    

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Pyramids of Biomass

The source of all energy is the sun as its light it pours onto the Earth and is photosynthesised by plants and some algae. Some of this light energy is stored as chemical energy which is passed on when a predator eats the plant or algae and the energy is passed through a food chain or food web.

Biomass is the mass of the material that is built up by energy from the sun.

A pyramid of biomass shows the amount of enery at each stage of the food chain. A pyramid of biomass is always shaped like a pyramid unlike pyramid of numbers.

The pyramid of biomass get shorter as it goes up because not all of the organisms are consumed by the level above, some of the energy is passed out as waste from the organisms and some energy is lost through other means (see next card).

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Energy Transfers

The biomass lessens as you go up the food chain.

One reson for this is that herbivores cannot digest all of a plant so the undigested parts are removed from the body through faeces.

The animals and plants respirate so lose energy through than and plants photosynthesise.

Animals and plants lose energy through growing.

Also, the movement of an animal takes away a large amount of energy because it transfers to kinetic and thermal energy.

They also use energy to keep their bodies at the same temperature.

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Decay Process - The Decay Process

The decay process is when animals and plants recycle nutrients, like when a tree's leaves fall or an aniaml dies. When an animal or plant does die, organisa called decomposers will break down the waste and dead animals and plants and then return the nutrients to the enviroment.

Decomposers are made up of fungi and bacteria. Firstly the detritus feeders such as maggots, eat dead animals and plants and their waste material will be digested by the bacteria and fungi.

The waste products of decomposers are water and carbon dioxide which can be used by plants to photosynthesise.

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Decay Process - Conditions and Importance of Decay

The conditions for temperature would be to make it warm. This is because if it is too cold the decomposers will slow down or maybe freeze but if it is too hot then their enzymes change shape and stop working.

Microorganisms also work better in moist conditions as this will make it easier to dissolve the food and prevents them from drying out.

Also, many decomposers must be in oxygen rich conditions as most micro-organisms need to respire to grow and reproduce.

If we didn' have decay then many of the Earth's resources would have run out years ago. We use micro-organisms in sewage treatment as they break it down so it is safe to be in rivers.

Also, in a compost heap the grass cuttings, vegetable peelings and weeds can be broken down to then be used as fertiliser. 

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The Carbon Cycle

The amount of carbon on Earth is fixed and some carbon is locked up in fossil fuels, oil, coal and gas and is only realeased when burned. When carbon is released and locked up we call this the carbon cycle.

When green plants photosynthesise they use the carbon in the carbon dioxide to make carbohydrates, fats and protein. This carbon is then passed onto animals when they eat the plant. This is how carbon is taken out of the enviroment.

Living organisms respire, this is where they break down glucose with oxygen to produce energy in their cells and carbon dioxide is released as a waste material.

When an animal is broken down by detritus feeders these too will also respire to release carbon dioxide.

Combustion is when something is burned with the presence of oxygen  and when coal or oil or gas is burned, carbon dioxide is produced from the locked up carbon in the fossil fuels.

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