2544171
Description
Mind Map by amy.hamilton, updated more than 1 year ago
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Created by amy.hamilton
almost 10 years ago
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Evolution: Variation
- Differences within a species
- Caused by:
organisms genes
or environment
- Genetic Variation
- Differences between
organisms due to
their genes
- Alleles: differences in
genes for particular
characteristics.
- Meiosis & fertilisation produce new combinations of alleles
- Possible to have completely new alleles form
sometimes
- Happens when a mistake is made as
DNA is being replicated e.g a missing
nucleotide, an extra nucleotide or a
nucleotide replacing another
- Happens when a mistake is made as
DNA is being replicated e.g a missing
nucleotide, an extra nucleotide or a
nucleotide replacing another
- Possible to have completely new alleles form
sometimes
- Meiosis & fertilisation produce new combinations of alleles
- Differences between
organisms due to
their genes
- In sexual reproduction, alleles are shuffled around, each time a new
organism is produced there is more chance of variation (More than in
a plant) because in principle any male gamete can fuse with any
female gamete
- Gives an almost infinite
number of combinations of
possible variations
- Environmental Variation
- Differences between organisms due to the environment
- 2 people with the same alleles to make them tall
but have very different diets can be very different
heights
- 2 plants with identical genes can be a
different size due to one being in the shade
& the other being in the sun
- 2 plants with identical genes can be a
different size due to one being in the shade
& the other being in the sun
- 2 people with the same alleles to make them tall
but have very different diets can be very different
heights
- Can arise throughout the lifetime but can not
be inherited as it is not caused by DNA
- Differences between organisms due to the environment
- Discontinous Variation
- Variation where each organism belongs to one of a few clearly defined groups
- E.g Human ABO Blood Groups: A, B, AB, O. No in-betweens
- Almost always caused by genes, with little or no environmental
influence
- Usually just 1/2 genes involved each having only a
few alleles e.g Human ABO blood groups are
controlled by a single gene with 3 alleles
- Usually just 1/2 genes involved each having only a
few alleles e.g Human ABO blood groups are
controlled by a single gene with 3 alleles
- E.g Human ABO Blood Groups: A, B, AB, O. No in-betweens
- Continous Variation
- Variation where there is a continuous range
of values between 2 extremes
- E.g eye or human skin colour is impossible to categorise in clearly defined
colours
- E.g Oxford Ragwort leaf length can range
between 2mm to 180mm, any length
between those values is possible
- E.g Oxford Ragwort leaf length can range
between 2mm to 180mm, any length
between those values is possible
- E.g eye or human skin colour is impossible to categorise in clearly defined
colours
- May be caused by genes, environment or both
- E.g human eye colour is genes
- Skin colour can be both due to how
much exposure to sunlight
- Leaf length is environmental due to how much
sunlight they get
- Leaf length is environmental due to how much
sunlight they get
- Skin colour can be both due to how
much exposure to sunlight
- E.g human eye colour is genes
- Most variations in humans is continuous
influenced by genes & environment
- Variation where there is a continuous range
of values between 2 extremes
- Variation where each organism belongs to one of a few clearly defined groups
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