Genetic Diversity and Natural Selection

Question 1

Define genetic diversity

Answer 1

The number of different alleles of genes in a species or population

Question 2

Give two things that increase genetic diversity within a population

Answer 2

1. Mutations in the DNA forming new allele
2. Gene flow

Question 3

Explain gene flow

Answer 3

Different alleles being introduced into a population when individuals from another population migrate into them and reproduce

Question 4

What is a genetic bottleneck?

Answer 4

An event that causes a big reduction in a population, this reduces the number of different alleles in the gene pool, and so reduces genetic diversity. The survivors reproduce and a larger population is created from a few individuals

Question 5

What does the founder effect describe?

Answer 5

What happens when a few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool

Question 6

How does the founder effect lead to a higher incidence of genetic disease?

Answer 6

The frequency of each allele in the new colony might be different to the frequency of those alleles in the original population - an allele that was rare in the original population may be common in the new colony

Question 7

How can the founder effect occur?

Answer 7

As a result of migration leading to geographical separation or if a new colony is separated from the original population for another reason, e.g. religion

Question 8

Explain natural selection

Answer 8

1. There’s different reproductive success in a population - individuals that have an allele that increase their chance of survival are more likely to survive, reproduce and pass on their genes (including the beneficial allele), than individuals with different alleles
2. So a greater proportion of the next generation have the beneficial allele
3. They, in turn, are more likely to survive, reproduce and pass on their genes
4. The frequency of the beneficial allele increases from generation to generation
5. Over generations this leads to evolution as the advantageous allele becomes more common in the population

Question 9

Give three different type of adaptations

Answer 9

1. Behavioural
2. Physiological
3. Anatomical

Question 10

What are behavioural adaptations?

Answer 10

Ways an organism act that increase its chance of survival and reproduction

Question 11

What are physiological adaptations?

Answer 11

Processes inside an organisms body that increase its chance of survival

Question 12

What are anatomical adaptations?

Answer 12

Structural features of an organisms body that increase its chance of survival