Evolution

Question 1

Evolution x2 definitions

Answer 1

A change in inherited characteristics of a group of organisms over time…
‘descent with modification’
or
‘…a change in allele frequency over time’

Question 2

Stabilising selection

Answer 2

-normally occurs when environment remains unchanged
-favours intermediate phenotypes
-selection against extreme forms

Question 3

Directional selection

Answer 3

-typically associated with a change in environment
-positive selection of more extreme phenotypes (graph shifts right)

Question 4

Disruptive selection

Answer 4

-can be considered as the opposite of stabilising selection…
-‘extreme phenotypes’ selected for
‘average phenotypes’ selected against

Question 5

Effect and implication of genetic drift

Answer 5

-loss of variation
-reduced ability to adapt

Question 6

Genetic Drift

Answer 6

In small populations…
-by chance, some individuals may have better breeding success than others and their alleles become more numerous
-or, due to random sampling during reproduction, alleles are not passed on

Question 7

Genetic bottleneck

Answer 7

population shrinkage than growth
-loss of advantageous alleles
-loss of harmful alleles

Question 8

Founder effect

Answer 8

new population established by a very small number of individuals from a larger population
-small gene pool/less variation