Topic 3

Question 1

The frequency of an allele in a __________ is/is not the same as the ratio in a ______ _____.

Answer 1

The frequency of an allele in a population is not the same as the ratio in a single cross.

Question 2

Evolution by natural selection will not occur when:

Answer 2

1. No variation is present
2. Variation is not heritable
3. Variation is heritable but has no fitness consequence (i.e does not impact the individual’s ability to survive).

Question 3

What happens to genetic variation in the absence of evolution?

Answer 3

It does not occur, variation remains unchanged.

Question 4

Hardy-Weinberg states that population allele frequencies do not change if:

Answer 4

1. There is no mutation
2. There is no gene flow (migration)
3. Population is infinitely large: no genetic drift
4. Genotypes do not differ in fitness: no selection
5. Mating is random

Question 5

What is the result of a population that achieves Hardy-Weinberg Equilibrium?

Answer 5

• allele frequencies will be the same between generations
• particular combination of genotypes will persist indefinitely

Question 6

What is p + q = 1 used to calculate?

Answer 6

Allele frequencies within a population: i.e how common is allele A in comparison to allele a?

Question 7

What is p² + 2pq + q² = 1 used to calculate?

Answer 7

Genotype frequencies: amount of individuals with homozygous dominant, heterozygous and homozygous recessive genotypes.

Question 8

Does a change in genotype frequency guarantee that evolution is occurring within a population?

Answer 8

No!
- Evolution is only confirmed when allele frequencies change over generations.
- Genotype frequencies can change without altering allele frequencies

Question 9

How can genotype frequencies change without altering the allele frequency?

Answer 9

AA, Aa and aa proportions can change without altering allele frequency.
The number of homozygous dominant/recessive individuals can increase while the number of heterozygous individuals decreases by an equal amount leading to the same p value.

Question 10

______ frequencies indicate evolution is occuring. ________ frequency indicates whether or not a population has achieved Hardy-Weinberg Equilibrium.

Answer 10

Allele frequencies indicate evolution is occurring. Genotype frequency indicates whether or not a population has achieved Hardy-Weinberg Equilibrium.

Question 11

True/False: A population can violate Hardy-Weinberg Equilibrium without undergoing evolution?

Answer 11

True! As long as allele frequencies remain the unchanged, a population can violate Hardy-Weinberg Equilibrium without undergoing evolution.