Ecosystems and populations

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what is an ecosystem?
all organisms in an area interacting with their biotic and abiotic factors
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what is a niche?
the role an organism plays within its habitat
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example of a biotic interaction
what an organism eats
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example of a abiotic interaction
when an organism is active
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what is a habitat?
where an organism lives in an ecosystem
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what is the name given to the process where adaptations become more common in a population?
natural selection
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what is a population?
organisms of the same species in a habitat
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what is a community?
organisms of different species in a habitat
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what is abundance?
the number of individuals of one species in a particular area
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what is distribution?
where a particular species is in an area you are investigating
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What is the equation for estimating a population using the mark-release-recapture method?
(no. caught in 1st x no. caught in 2nd) / no. marked in 2nd
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what assumptions affects the mark-release-recapture?
marked samples have enough time to mix back in with population, marking hasn't affected chance of survival, deaths and births are small during period of study
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what is the birth rate?
the number of live births each year for every 1000 people in the population
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how is the population growth rate calculated?
birth rate - death rate
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what conditions does the hardy weinberg principle work under?
large population with no immigration, emmigration, mutation or natural selection, random mating so all genotypes are possible
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what is a species?
organisms which can breed to produce fertile offspring
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what is a gene pool?
complete range of alleles in a population
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what does the hardy weinberg principle predict?
that allele frequency will not change
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what is stabilising selection?
type of natural selection where individuals with alleles for characteristics towards middle are more likely to survive as there is no change in environment and this reduces range of phenotypes
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what is directional selection?
type of natural selection where individuals with alleles for characteristics of an extreme are more likely to survive and reproduce. Could be response to environmental change
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how does speciation occur?
geographical isolation, different selective pressures e.g. temperature, different alleles favoured so directional selection, mutations occur independently, changes in gene pool, over time individuals are so different they cant breed
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Other cards in this set

Card 2

Front

what is a niche?

Back

the role an organism plays within its habitat

Card 3

Front

example of a biotic interaction

Back

Preview of the front of card 3

Card 4

Front

example of a abiotic interaction

Back

Preview of the front of card 4

Card 5

Front

what is a habitat?

Back

Preview of the front of card 5
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