1.7 Criteria Flashcards
What is evolution?
Describes the changes in organisms over generations as a result of genomic variations arising through mutation.
What is meant by natural selection?
The weeding out of individuals of a species with a phenotype less suited to their environment.
Is natural selection random or non-random?
it is the non-random decrease or increase in frequency of DNA sequences and changes survival rates.
What are the three changes in phenotype frequency that can occur?
- Stabilising selection
- Directional selection
- Disruptive selection
What is stabilising selection?
Where an average phenotype is selected for and extremes of the phenotype are selected against.
What is directional selection?
Where an extreme of the phenotype is selected for.
What is disruptive selection?
Where two or more phenotypes are selected for.
Why is natural selection rapid in Prokaryotes?
Due to the short generation times.
How do prokarytoes exchange genetic material?
They exchange genetic material horizontally meaning genes are transferred between organisms in the same generation.
Is horizontal transfer rapid or slow?
Rapid
What is meant by vertical gene transfer?
The transfer of genes from parent to offspring in sexual or asexual reproduction.
Define species:
A group of organisms capable of interbreeding to produce fertile offspring, and which does not normally breed with other groups.
What is speciation?
The generation of new biological species by evolution.
How does specaition occur?
Through isolation, mutation and selection
What type of barriers are essential to prevent gene flow between sub-populations during speciation?
Isolation barriers
