In GCSE Science students will look at energy and biomass in food chains. This is the second of three quizzes on that subject and it looks specifically at the decay and recycling of dead and waste material, or waste management.
When we think of waste management we think of dustbin men and litter pickers. Many trees shed their leaves each year and most animals produce droppings at least once a day. All plants and animals eventually die so why are we not knee-deep in leaves, droppings and dead animals in the countryside? Is there someone who goes round cleaning up?
Of course not! It all happens naturally as part of the cycles of life. Waste and dead material will naturally decay. Microorganisms play an important part in decomposing waste material and animal carcasses so that the chemicals from which they are made can be used again by plants. The same material is recycled over and over again and can lead to stable communities.
In situations where something is removed from the system, the whole food web can break down as the plants do not get the nutrients they need to thrive. That is why farmers need to use fertilisers - as the crops are taken away, no nutrients are put back into the soil naturally so without fertilisers, the next crops would not be as good.
The compost heap in your garden is an artificial form of nature's recycling system. By placing uncooked food waste like vegetable peelings and grass cuttings in a pile or in a composting bin, they can rot down and decay and then be added back to the soil. Humans create vast amounts of rubbish which is taken to landfill sites. Part of the rubbish is garden waste. When this decomposes in a landfill site, the nutrients are wasted. This is poor management. Most local authorities run composting schemes where the garden waste is separated and sent for composting instead of to landfill sites.
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