Evolution

Question 1

What can lead to variations in phenotypes?

Answer 1

Genetic and environmental factors

Question 2

What is the primary source of genetic variation?

Answer 2

Mutation

Question 3

What are other causes of genetic variation?

Answer 3

• Meiosis

- The random fertilisation of gametes during sexual reproduction

Question 4

What causes natural selection?

Answer 4

Predation, disease and competition for the means of survival resulting in differential survival and reproduction. Those organisms with phenotypes providing selective advantages are likely to produce more offspring and pass on their favourable alleles to the next generation.

Question 5

What are the 3 types of selection?

Answer 5

Stabilising, directional and disruptive.

Question 6

What is the effect of stabilising selection?

Answer 6

Reduces genetic variation within a population

Question 7

What is the effect of directional selection?

Answer 7

Directional selection has no effect on the amount of genetic variation in a population. Directional selection causes on extreme of a trait to be selected over the other extreme. This causes the distribution pattern of the trait to shift in the direction favoured by natural selection.

Question 8

What is the effect of disruptive selection?

Answer 8

Increases genetic variation within a population

Question 9

What is evolution?

Answer 9

A change in the allele frequency in a population

Question 10

How does speciation occur?

Answer 10

Reproductive separation of two populations can result in the accumulation of difference in their gene pools. New species arise when these genetic differences lead to an inability of members of the populations to interbreed and produce fertile offspring. In this way, new species arise from existing species.

Question 11

What is sympatric speciation?

Answer 11

The process through which new species evolve from a single ancestral species while inhabiting the same geographic region

Question 12

What is allopatric speciation?

Answer 12

The process through which new species evolve from a single ancestral species while geographically separated

Question 13

What is genetic drift?

Answer 13

Variation in the relative frequency of different genotypes in a small, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

Question 14

Why is genetic drift only important in small populations?

Answer 14

In larger populations it is less likely that a gene will disappear