carbon dioxide (photosynthesis), plants (eaten), aniamls (death and decomposition of plants and animals), (respiration), carbon dioxide in the air. also respiration from plants and animals returns it to the air.
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describe the nitrogen cycle...
nitrogen in the air (nitrogen-fixing bacteria) plants (eaten) animals (death of plants+animals) (nitrogenfying bacteria) in soil (back to plants or denitrofing Bacteria) plants or the air. also fertilisers add to plants
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describe selective breeding
breeding an animal with a certain traits to produce offspring with more pronounced traits (done by humans)
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negative effects of human activity on aniamls
extinction, over killing, new predators and destroying habitats)
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what does biodiversity and do you sustain it?
variety of life on earth. providing for the population while protecting the enviroment
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what do fossils show and how do they form?
they show how species have evolved. they form from parts of organisms that don't decay easily and markings preserved in sedimentary rock
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what does DNA tell us about evolution?
it shows many animals share the similar DNA so must have a commkn ansestor
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describe natural selection
1)an individual shows varriation 2)they are better adapted so suvive as are better than the competition 3)adapted ones reproduce and pass on adaptation
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what is Lamack's theory?
he thought that animals changed to suit their environment. he was wrong
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what is a ecosystem?
a self-sustained community of organisms
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how is energy lost by organisms?
heat/respiration, waste products and trapped in materials (bone/fur)
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how did life on Earth start and develop?
simple organisms in the sea (unknown origin) then animals developed through evolution
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why do animal populations decrease?
increased competition, new predators and new diseases
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what do food chains show?
the feeding relationship between animals and how energy is transfered
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what do food webs show?
how all the food chains in a habitat are inter-related and how animals have varied diets
nitrogen in the air (nitrogen-fixing bacteria) plants (eaten) animals (death of plants+animals) (nitrogenfying bacteria) in soil (back to plants or denitrofing Bacteria) plants or the air. also fertilisers add to plants
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