5.1 a2 biology

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5.1 What is an ecosystem?
Biospherethe part of the earth and it's atmosphere inhabited by living organisms.
Ecosystemall the organisms living in a particular area as well as the nonliving features
of that environment, they are self sustaining.
factors that affect an ecosystem can be split into two:
1. Abiotic (nonliving)
eg, water, sunlight, oxygen, topographic, edaphic factors (soil).
2. Biotic (living)
eg, predation, competition
interspecific different species
intraspecific same species
within and ecosystem you find many different habitats.
habitat The particular place where a community of organisms is found, and the distinct
set of conditions that comes with. eg, within a pond you have surface habitats, mud
habitats etc...
within a habitat there will be several to many populations of an organism. A population is
a group of the same species that are able to interbreed to produce fertile young. Within a
habitat various populations make up a community. if two species share the same niche
one will out compete the other. only if species occupy different niches can they survive in
the same community.

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Biotic factors are generally density dependant
the abundance and distribution of organisms in an area are generally controlled by biotic
and abiotic factor, normally in a complicated interaction of the two.
Anthropogenic factors
Anthropogenic factors are those that arise from human activity. They may be either biotic or
abiotic and our influence on the environment around us is larger than any other organism at
present.…read more

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As succession progresses the number of niches also increases however at climax the
biodiversity can often decrease
the climax community does not always consist of trees if there are conditions that make
it impossible to go past the first stage of succession then this is the climax community.
This often encourages rarer species that, whilst they cannot compete with other species,
can survive in harsh conditions
Secondary succession
Secondary succession occurs when the soil is already there but the previous community has
been cleared.…read more


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