Decay Biology Unit 2

Yeah, just some info if your revising like me :)

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  • Created by: lucy
  • Created on: 16-10-11 14:03


When animals/plants decay,all material is recycled and given back to our enviroment. Organisms called decomposers, help to decompose dead animal/plants through 'decaying them,' as they feed on waste.

These decomposers are bacteria and fungi. Waste products through the process of decay, include

-Carbon dioxide and water.

Microorganisms digest the dead body by feeding on them.

The speed of decay on certain things depends on things like-

-Tempeture-Micro-organisms work best at warm tempetures, and will slow down or even stop working in cold conditions. They also will stop working in conditions which are too hot, as microorganisms are controlled by enzymes, and enzymes become denatured at tempetures which are too hot.


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Moist Conditions- Micro-organisms also work best in moist conditions because moisture makes it easier to digest food.

Oxygen- Microorganisms also need oxygen to work. This is because they need oxygen to grow/respire. If this is the case, microorganisms work best when there is a lot of oxygen present.

Decomposers are also important for recycling waste. We use micro-organisms to break down waste at sewage works.

We also use micro-organisms to decay old food and grass clippings to make compost. Micro-organisms decompose these old plant materials, making fertile soil full of mineral nutrients released by micro-organisms.

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Most carbon is locked up in

-Coal, Oil, gas, ocean, plants, sedimentry rocks.

The carbon cycle is the way in which we have carbon recycled and reused, this therefore keeping a constant balance of locked up carbon dioxide, and released carbon dioxide.

Photosynthesis uses carbon to make biomass, it takes in the carbon released through animal and humans respiring.

When we burn fossil feuls we also release carbon dioxide.

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Energy in Food production

Plants are very energy efficiant because they contain the most biomass.

Every time we eat an animal, we are losing out on energy used by the animal while it was alive. This means animals are not very energy efficiant to eat.

Farmers use methods so that we can get the most possible biomass and energy from the animals we eat as well as doing so in a way that means we can buy cheap meat.

They do this through controlling the tempeture and light of farms, and limiting the movement of animals.

Limiting the movement of animals- Waste minimal energy moving and therefore have extra enegry in which they can use to grow.

Controlling temp- So animals won't lose energy keeping themselves warm, and will have more energy for growth.

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Advantages and Benifits of Intensive rearing and f

Benifits of Intensive rearing- Lots of chickens, cheap meat, no wastage in energy, lots of biomass.

Disadvantages of Intensive rearing- Chickens unable to behave naturally, expensive electricity costs, risk of disease due to lack of space.

Adavantage of free-range farming- Chickens lead more natural lives, no heating or lighting costs, people will spend more on free-range eggs.

Disadvantages- More land needed for free-range chickens, fewer eggs laid, takes longer for chickens to reach maximum size.

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