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Flashcards in Key Words Deck (29):
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Mutation

Any change to the quantity or structure of an organism's DNA

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Allele

Alternative form of a gene

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Phenotypes

The visible characteristics of an organism, resulting from its alleles

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Phenotypic variation

The total variation in the characteristics of an organism, usually resulting from its genotype and the effects of its environment

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Population

All the freely interbreeding individuals of the same species occupying the same place at the same time

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Allele frequency

The number of times an allele occurs within the gene pool

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Parasites

An organism that lives on or in another organism that may cause harm

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Genetic factors

Presence of certain alleles

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Environmental factors:

Food availability/availability of mates

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Selective advantage

A variation that gives an organism an advantage over another, so it is more likely to survive and reproduce

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Intraspecific competition

Competition between organisms of the same species

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Natural selection

The process by which the best adapted organisms in a population survive, reproduce and pass on their alleles to their offspring

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Selection pressure

The environmental force altering the frequency of alleles in a population

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Speciation

The process by which new species develop

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Reproductive isolation

When groups within the population become isolated from another and cannot interbreed

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Gene pool

All the genetic information present within a population at a given time

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Allopatric speciation

Occurs when populations are prevented from interbreeding because they become geographically isolated

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Sympatric speciation

Occurs when populations living together are prevented from interbreeding, e.g. Reproductively isolated, but remain in the same place

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Prezygotic mechanisms

Reproductive isolating mechanism that takes place before fertilisation

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Post zygotic mechanisms

Reproductive isolating mechanism that takes place after fertilisation

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Geographical variation

Populations are isolated by physical barriers, e.g. Oceans

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Ecological variation

Populations inhabit different habitats within the same area and so individuals rarely meet

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Temporal variation

The breeding season of each population do not coincide and so they do not interbreed

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Behavioural variation

Changes in courtship, call, actions of particular mate prevents interbreeding

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Mechanical variation

Anatomical differences may prevent mating occurring

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Gametic variation

Gametes may be prevented from meeting due to genetic or biochemical incompatibility

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Hybrid sterility

Hybrids formed from a fusion of gametes from different species are often sterile because they cannot produce gametes

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Hybrid inviability

Despite fertilisation taking place, further development does not occur or fatal abnormalities arise in early growth - don't reach maturity: no breeding

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Hybrid breakdown

The first generation of hybrids if fertile but the second generation fails to develop or, if it does, it is sterile