Unit 1.7 - Evolution

Created by

Kirsty Kitchin

Cards (21)

What is evolution?
The change that occurs in organisms over generations as a result of genomic variations
What are the two types of gene transfer?
Horizontal and vertical gene transfer.
What is vertical inheritance?
Genes are transferred from parents to offspring as a result of sexual or asexual reproduction
What is horizontal transfer of genetic material?
Genes are transferred between individuals in the same generation. Prokaryotes can transfer genetic material from one cell to another horizontally.
Why is evolution more rapid in prokaryotes?
They can exchange genetic material horizontally.
Why is vertical gene transfer safer than horizontal?
The parent cells have already tested the genes
What is selection?
The frequencies of some DNA sequences increase in a population because they have been selected for and some decrease because they have been selected against
What is natural selection?
The non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in deleterious sequences.
Why is there a reduction of deleterious sequences after selection?
They are poorly adapted to the environment so will die out quicker and more frequently and leave fewer offspring.
What is a quantitative trait?
A measurable phenotype that depends on the cumulative actions of genes and the environment. They are polygenic, so they are controlled by many genes working together. These traits can vary over a range to produce a continuous distribution of phenotypes.
What are the 3 types of selection for a quantitative trait?
Directional selection, stabilizing selection, and disruptive selection.
What is a stabilising selection?
An average phenotype is selected for and extremes of the phenotype range are selected against.
What is a directional selection?
One extreme of the phenotype range is selected for
What is a disruptive selection?
Two or more phenotypes are selected for
What is a species?
A group of organisms than are able to interbreed to produce fertile offspring
What is speciation?
The formation of a new species brought about by evolution as a result of isolation, mutation and selection
Why are isolation barriers important?
They prevent gene flow between subpopulations during speciation
What are the two types of speciation?
Allopatric and sympatric speciation.
What is allopatric speciation?
Population becomes seperated due to a geographical barrier
What is sympatric speciation?
When 2 populations live in the same environment, but become isolated due to behavioral or ecological barriers.
What are examples of ecological barriers?
Temperature and pH