Bio Topic 4; Variety of Species

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Define species
a group of organisms with similar morphology, physiology and behaviour that can interbreed to produce fertile offspring.
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Horses & Donkeys are very similar in features and behaviours and can interbreed to produce offspring. So why are they 2 different species?
Because their offspring (mules) are infertile.
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The finches of Galapagos islands can interbreed to produce hybrids so we'd expect a wide range of non-distinct species. Why is this not so?
There's enough change in the environment's climate to maintain the different species as hybrid birds don't survive the environment as well as pure bred birds.
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Why can't DNA always tell us if animals are 2 species or 1?
Because the DNA analysis doesn't tell us if the two animals can produce fertile offspring. For that we need to observe them in their natural habitat.
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Why do offspring only have their mother's mitochondrial DNA?
Because most of the sperm's mitochondrial DNA doesn't enter the ovum during fertilisation and any that does is broken down in the ovum.
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Define biodiversity
The variety of species that occurs within a group of organisms as well as the variation that occurs within a species.
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What causes genetic diversity in a species?
Sexual reproduction causes organisms to have a unique combo of alleles plus variation in the organism's gene's occur through interactions between the genotype and the environment.
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Give 2 sources of variations given by mutations.
Gene point mutations: alterations of DNA base sequence (insertions/deletions/replacements) form new alleles. Chromosome mutation: small sections of chromosome may be inverted, moved to another chromosome or lost entirely.
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How does the production of gametes produce sources of variation?
Independent Assortment: Random assortment of homologous chromosomes sorted independently to one another to opposite ends of the cell. Crossing Over: New alleles formed when genetic material exchanged between homologues chromosomes.
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How does the process of fertilisation produce sources of variation?
Mate Selection: Different combo of alleles come tog. in the offspring depending on which 2 parent mate. Random fertilisation: different combo of alleles will come together in the offspring depending on which sperm and egg is involved in fertilisation
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What is gel electrophoresis?
A laboratory method used to separate mixtures of DNA, RNA or proteins according to their molecular size.
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What is species richness? Why is only possible to list some species present?
Found by counting the number of species present in a given habitat. As some of the species are too small to see with the naked eye eg. bacteria and fungi.
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What is the limitation of using species richness?
It doesn't take into account the population size of each of the species.
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What is a community with high species evenness ?
Most of the species present in the community have a similar abundance so no one species dominates the others.
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How would a community have low species evenness?
The species present would have a similar abundance but one of these species dominates the rest.
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In terms of species richness & evenness, what would a highly diverse community look like?
High species richness + high species evenness.
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What is a diversity index?
a mathematical way of calculating biodiversity that takes into account species richness & evenness.
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Give an example of a diversity index
D= N(N-1) / sum of ( n(n-1) ) where N= total no. of organisms of all species and n= total no. of organisms of each species.
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Calculate the diversity of a rock pool containing 27 top shells, 305 barnacles, 4 limpet and 2 sea otters
D=1.23
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What is the criteria for a hotspot?
Much have more than 1250 species & 0.5% of the plant population must be endemic
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Define endemic
Species native or unique to a certain area, not found anywhere else.
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Why can endemic species easily become extinct or endangered?
Because of their restricted habitat and vulnerability to human and new species.
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Other cards in this set

Card 2

Front

Horses & Donkeys are very similar in features and behaviours and can interbreed to produce offspring. So why are they 2 different species?

Back

Because their offspring (mules) are infertile.

Card 3

Front

The finches of Galapagos islands can interbreed to produce hybrids so we'd expect a wide range of non-distinct species. Why is this not so?

Back

Preview of the front of card 3

Card 4

Front

Why can't DNA always tell us if animals are 2 species or 1?

Back

Preview of the front of card 4

Card 5

Front

Why do offspring only have their mother's mitochondrial DNA?

Back

Preview of the front of card 5
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