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Summary AQA ALEVEL BIOLOGY NOTES ON GENETIC DIVERSITY AND NATURAL SELECTION
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ALEVEL NOTES ON GENETIC DIVERSITY AND NATURAL SELECTION ADJUSTED TO THE AQA SPECIFICATION AND MADE FROM MARKSCHEMES
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Genetic Diversity & Natural Selection =tityÉ Evolution
different alleles of a
gene
in a
population .
frequency
→ in
:
change allele over time
"E
? factor natural
Genetic diversity is a
enabling selection to occur .
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1 Random DNA mutations cause
genetic variation within a population .
Selection /
2
pressure change in environment
( differential reproductive success )
Those with
3
advantageous allele ( and
phenotype) are more
likely to survive and reproduce .
4 Passing on the advantageous allele to
offspring .
5 Frequency of advantageous allele ( and
phenotype) increases in the population .
6 Over
many generations
Bottleneck reduces
severely
%
iity
population size and
Genetic Bottleneck
*÷÷¥
Population / genetic bottleneck is the of
→
a
sharp reduction in size a
population .
~
A
genetic bottleneck happens when population is
drastically reduced
-
a
in size
due to a natural catastrophe or
a continual more
gradual change in the
environment .
Former
population New
population
( Higher genetic ( Lower
genetic
The Founder Effect % diversity ) diversity ,
÷÷÷÷
-
The founder effect occurs when a small number
of individuals colonise a new habitat and star t
a new
,
isolated population .
Since the few individuals will have
only small
•
a
range of alleles between them ,
the founder
effect is example of bottleneck
an a
genetic .
foggy
Types of Adaptations
%
' "" " " - - e - a- a -
%
"
1- Behavioural "
survival dead)
adaptation - how it acts to increase chance (
e.g playing
survival chance ( bears
2
Physiological adaptation -
processes to increase
e.g . brown hibernating)
Anatomical adaptation -
structural features to increase survival chance ( e.g streamlined shape
3
.
of otters
)
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