Key Area 1.7 Evolution Flashcards
What is evolution?
Evolution is the change that occurs in organisms over generations as a result of genomic variations. These variations take the form of changes of frequencies of certain genetic sequences.
What are the 2 ways that genes can be passed on?
Vertical gene transfer and horizontal gene transfer.
What is vertical gene transfer?
Genes are transferred from parent to offspring as a result of sexual or asexual reproduction.
What is horizontal gene transfer?
Genes are transferred between individuals in the same generations.
What kind of cells can perform horizontal gene transfer?
Prokaryotes.
In what kinds of cell is evolution more rapid?
Prokaryotes.
Why is evolution quicker in prokaryotes?
They can exchange genetic material horizontally.
Why is vertical gene transfer seen as safer?
The genes have been ‘tried and tested’ by the previous generation.
What is selection?
Selection is the process by which 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 nonrandom increase in frequency of DNA sequences that increase survival and the nonrandom decrease in deleterious sequences.
What is a deleterious sequence?
A gene that codes for an inferior characteristic.
What are the 3 types of quantitive traits?
- Stabilising
- Directional
- Disruptive
What happens at a stabilising quantitive trait?
An average phenotype is selected for and the extreme phenotypes are selected against.
What happens at a directional quantitive trait?
One extreme phenotype is selected for.
What happens at a disruptive quantitive trait?
Two or more extreme phenotypes are selected for.
