unit 4 aos 2

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ToxicWarthog48962

Cards (12)

What is a mutation?
any change to the DNA of an organism that is unpredictable and random
How are mutations characterised based on size?
Single base = point mutation
More than a whole gene = block mutation
Extra/missing chromosome = aneuploidy
Whole extra set of chromosomes = polyploidy
What is selective advantage?
The phenotype that makes the greatest contribution to the gene pool in the next generation has a higher fitness value and is at a selective advantage
What is natural selection?
the survival and reproduction of individuals in a species due to selective advantage and disadvantage of the heritable phenotype
What are the five characteristics of natural selection?
Variation, environmental changes, selective advantage, survival and reproduction, change in allele frequency
What are selection pressures and provide some examples
Influence the survival of individuals in a population/species. This can include; Predation, food availability, competition for mates/resources, disease, increasing temperature (C4 plants), reduced water
What is genetic drift?
a change in the frequency of alleles in a gene pool due to chance events. This results in decreased genetic diversity.
Explain the genetic drift founder effect
The founder effect – the formation of a new population by a non-representative sample of individuals from an original population
Explain the genetic drift genetic bottleneck 
a population grows following a near-extinction event, but the frequency of alleles changes because the individuals that survived are not representative of the original population
Explain gene flow 
the transfer of genetic information from one population to another by migration
What is speciation? 
the emergence of new species from a population
Explain allopatric speciation 
a model of speciation where a population becomes isolated from its species due to geographical barriers (ocean, mountains, lava flow, canyon, river, desert, land), resulting in the emergence of new species