evolution mechanisms

Question 1

What is genetic drift? (4)

Answer 1

Random changes in allele frequencies,

Occurs without selective forces, -

Chance dictates which alleles are passed on,

Greater effect in small populations

Question 2

Why is genetic drift more important in small populations? (3)

Answer 2

Random changes in allele frequencies cause larger percentage changes in small populations,

In large populations, chance variations tend to even out, -

Small populations are more influenced by random effects

Question 3

What is a genetic bottleneck? (4)

Answer 3

Event causes a big reduction in population size,

Leads to a smaller gene pool, -

Chance determines which alleles survive,

Surviving alleles become more frequent

Question 4

What is the founder effect? (4)

Answer 4

1. A small group from a population starts a new population,
2. Initial gene pool is limited,
3. Reduced genetic variation in new population,
4. Greater effect of genetic drift in the new population

Question 5

What is a species and what is a population? (2)

Answer 5

Species = A group of similar organisms that can reproduce to give fertile offspring, -

Population = A group of organisms of the same species living in the same habitat, with the potential to interbreed

Question 6

What is the gene pool and allele frequency? (2)

Answer 6

Gene Pool: The complete range of alleles present in a population,

Allele Frequency: How often an allele occurs in a population

Question 7

What does the Hardy-Weinberg principle predict? (2)

Answer 7

The frequency of alleles of a particular gene,

Will stay constant from one generation to the next

Question 8

What are the requirements for the Hardy-Weinberg principle to apply? (5)

Answer 8

1. No mutations.,
2. No natural selection (all alleles equally advantageous),
3. The population is large,
4. The population is genetically isolated,
5. Random mating

Question 9

What factors affect allele frequency? (3)

Answer 9

Migration,
Mutations,
Selection pressures