Flashcards · Biology · Variation and Evolution
Variation
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What is variation?
Differences in the characteristics of individuals in a population.
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Name three possible causes of variation.
Genes, the environment, or a combination of both.
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Give an example of a characteristic caused only by genes.
Eye colour or blood group.
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Give an example of a characteristic caused by the environment.
Scars, or the language you speak.
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Give an example of a characteristic caused by genes and the environment.
Height or body mass.
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Where do all genetic variants come from?
Mutations.
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How often do mutations occur?
Continuously.
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What do most mutations do to the phenotype?
Nothing.
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What do a very few mutations do to the phenotype?
Determine it.
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What can happen if a rare mutation gives a phenotype suited to a changed environment?
A relatively rapid change in the species.
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Why is variation important for a species?
It means some individuals may survive if the environment changes.
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What is the modal class on a frequency chart?
The tallest bar, the group with the most individuals.
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Do identical twins have exactly the same phenotype?
No. The environment gives small differences.
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Is there usually a lot or a little genetic variation in a population?
Extensive variation.
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What shape is a frequency chart for height?
Bell-shaped.
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Sort these into genetic, environmental or both: eye colour, scars, height, language spoken.
Eye colour is genetic. Scars and language spoken are environmental. Height is both.