Patterns of Inheritance

Question 1

What is epistasis?

Answer 1

When the allele of one gene affects the expression of another gene in the phenotype

Question 2

What is a dihybrid cross?

Answer 2

Shows the simultaneous inheritance of two genes controlling different characteristics

Question 3

When do you accept the null hypothesis?

Answer 3

When the chi squared value is lower than the CV at the 5% significance level

Question 4

What is genetic drift?

Answer 4

• A change in allele frequency that occurs by chance, not as a result of natural selection
• Most likely to happen when a small number of individuals are separated from the rest of a large population

Question 5

What is the founder effect?

Answer 5

• An extreme example of genetic drift
• Where small populations arise due to the establishment of new colonies by a few isolated individuals
• Leads to smaller gene pools and less genetic diversity in a population, compared with the original population

Question 6

What is the bottleneck effect?

Answer 6

• Large reduction in population size that lasts at least one generation
• Reduces gene pool and genetic diversity, leading to problems of inbreeding and reduced fertility

Question 7

What do the letters in the hardy weinberg equation represent?

Answer 7

p = dominant allele frequency
q = recessive allele frequency
p2/q2 = frequency of homozgous dominant/recessive genotype
2pq - frequency of heterozygous genotype

Question 8

Explain sympatric speciation

Answer 8

• Type of speciation that results within a population without any geographical separation
• Instead, ecological or behavioural separation lead to the groups becoming reproductively separated with no gene flow, leading to the formation of a new species
• Less frequent than allopatric

Question 9

What are the steps in artificial selection?

Answer 9

1. Select a population showing variation
2. Select individuals with desired traits
3. Breed these individuals together
4. Grow and test the offspring
5. Repeat this process until the desired traits are achieved

Question 10

What are some ethical issues with artificial selection? Give an example

Answer 10

• The limited gene pool and low genetic diversity that is introduced with inbreeding
• This can result in many homozygous recessive traits that can be harmful
• For example, many pedigree dog breeds experience health issues like heart, brain, respiratory or spinal problems

Question 11

What are gene banks?

Answer 11

Store biological samples such as egg cells or sperm cells

Question 12

What are wild type alleles, and why is it important to store them or maintain them in the wild?

Answer 12

• Those that code for the most normal or common characteristic
• From seed or gene banks, or from the wild, they can be used for outbreeding
• This can increase the genetic diversity after it has been reduced by inbreeding, reducing the frequency of recessive alleles that may be harmful, and increases the ability of populations to adapt to environmental change