unit 1 KA7 - evolution Flashcards

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1
Q

what is evolution

A

evolution is the changes in organisms over generations as a result of genomic variations

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2
Q

what is natural selection

A

natural selection is the non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences

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3
Q

what are the three types of natural selection

A
  • stabilizing
  • directional
  • disruptive
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4
Q

describe stabilizing selection

A

in stabilizing selection, an average phenotype is selected for and extremes of the phenotype range are selected against

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5
Q

describe directional selection

A

in directional selection, one extreme of the phenotype range is selected for

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6
Q

describe disruptive selection

A

in disruptive selection, two or more phenotypes are selected for

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7
Q

what is horizontal gene transfer

A

horizontal gene transfer is where genes are transferred between individuals in the same generation

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8
Q

is natural selection more rapid in prokaryotes or eukaryotes

A

prokaryotes

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9
Q

why is natural selection more rapid in prokaryotes

A

because prokaryotes can exchange genetic material horizontally, resulting in faster evolutionary change than in organisms that only use vertical transfer

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10
Q

what is vertical gene transfer

A

this is where genes are transferred from parent to offspring as a result of sexual or asexual reproduction

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11
Q

what is speciation

A

speciation is the generation of new biological species by evolution as a result of isolation, mutation and selection

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12
Q

what is a species

A

a species is a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups

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13
Q

why are isolation barriers important

A

they prevent gene flow between sub-populations during speciation

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14
Q

which type of barriers lead to allopatric speciation

A

geographical

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15
Q

which type of isolation barriers lead to sympatric speciation

A

ecological or behavioural

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16
Q

what is allopatric speciation

A

this is when a new species arises due to isolation of a population by geographical barriers

17
Q

what is sympatric speciation

A

speciation where a new species arises despite occupying the same geographical area

18
Q

what are examples of ecological barriers

A
  • occupying different habitats or breeding areas or pH or salinity
19
Q

what are examples of geographical barriers

A

rivers and mountain ranges

20
Q

what are examples of behavioral barriers

A

different timings, locations or mating dances of complex mating rituals