Unit 1.7: Evolution

Question 1

What is evolution?

Answer 1

Evolution describes the change in organisms over generations as a result of genomic variation

Question 2

What are the types of gene transfer?

Answer 2

Vertical gene transfer - occurs from one generation to the next
Horizontal gene transfer - occurs within a population of the same generation

Question 3

What is natural selection?

Answer 3

Natural selection is the non-random increase in frequency of DNA sequences that increases survival and the non-random decrease in frequency of deleterious alleles. Natural selection is the mechanism by which evolution occurs.

Question 4

What are the 3 types of selection?

Answer 4

1. Stabilising selection - favours the mid range phenotype
2. Directional selection - favours an extreme phenotype
3. Disruptive selection - favours two phenotypes

Question 5

What is a species?

Answer 5

A group of organisms capable of interbreeding to produce fertile offspring and which doesn’t not normally breed with other groups

Question 6

Describe speciation

Answer 6

The generation of new biological species by evolution as a result of isolation, mutation and selection

Question 7

What are the 2 different types of speciation?

Answer 7

• Sympatric speciation happens in a sub-population living side by side and is due to reproductive, ecological or behavioural barriers
• Allopatric speciation involves geographical barriers