Populations Genetics

Question 1

What are linked genes?

Answer 1

Linked genes are genes that map to the X chromosome more than the Y chromosome.

Question 2

What is the sex chromosome composition of individuals with XY?

Answer 2

•Individuals with XY are male

•Individuals with XY are homozygous for X chromosome genes

Question 3

What are sex-linked genes?

Answer 3

Sex-linked genes are genes that are located on sex chromosomes.

Question 4

What factors can influence gene expression?

Answer 4

Factors include mutation, natural selection, gene flow and genetic drift

Question 5

What determines the number of animals that can survive in a habitat?

Answer 5

The carrying capacity of the habitat determines the maximum
number of animals that can survive.

Question 6

What is the significance of the X chromosome in sex-linked traits?

Answer 6

The X chromosome carries many genes that can influence traits in both sexes.

Question 7

What are sex limited genes?

Answer 7

Copies carried on by both sexes but only expressed in one

Question 8

What is an example of a sex limited gene?

Answer 8

Beetle mandibles

Question 9

What is sex influenced gene expression?

Answer 9

The expression of genes is dependent on sex/ gender

Question 10

What is an example of a sex influenced gene?

Answer 10

Baldness impacted by testosterone levels

Question 11

What is the carrying capacity dependent upon?

Answer 11

Resources (Food, water and shelter)

Question 12

What is population growth and change influenced by?

Answer 12

Pressures applied by a habitat

Question 13

What are sex-linked genes also known as?

Answer 13

X-linked genes

Question 14

What chromosome pair is homozygous for X chromosome genes?

Answer 14

XY

Question 15

What are sex-limited genes?

Answer 15

Copies carried by both sexes but only expressed in one

Question 16

What influences sex-influenced gene expression, such as male baldness?

Answer 16

Testosterone levels

Question 17

What is the study of change in allele frequency called?

Answer 17

Population genetics

Question 18

List the four forces that influence allele frequency.

Answer 18

• Genetic drift
• Mutation
• Natural selection
• Gene flow

Question 19

What does carrying capacity refer to?

Answer 19

An ecosystem’s maximum number of organisms of a species that can survive

Question 20

What factors can impact carrying capacity?

Answer 20

• Resources (food, water, shelter)
• Stochastic events
• Environmental factors
• Genetic factors
• Demographic factors

Question 21

What is environmental stochasticity?

Answer 21

Variability in the environment that can affect population sizes

Question 22

Give examples of major natural disasters that contribute to environmental stochasticity.

Answer 22

• Flood
• Drought

Question 23

What is genetic stochasticity?

Answer 23

Variability due to small population sizes

Question 24

What is demographic stochasticity?

Answer 24

Chance nature of birth and death events in a population

Question 25

What is a genetic bottleneck?

Answer 25

Occurs when a population is greatly reduced in size, limiting genetic diversity because only a small part of the original population survives

Question 26

What can cause a genetic bottleneck?

Answer 26

* Natural disasters * Overhunting * Habitat destruction

Question 27

What is a mutation?

Answer 27

A change in the DNA sequence of an organism

Question 28

What is the Hardy-Weinberg equation used for?

Answer 28

To calculate allele frequencies in a large population

Question 29

What is the Hardy-Weinberg equation useful for?

Answer 29

* Breeding programs * Genotype numbers in a population

Question 30

What are the variables in the Hardy-Weinberg equation?

Answer 30

* p = frequency of dominant allele * q = frequency of recessive allele * p² = frequency of homozygous dominant * q² = frequency of homozygous recessive * 2pq = frequency of heterozygous

Question 31

What assumptions are made in the Hardy-Weinberg principle?

Answer 31

* Sexually reproducing * Discrete generations * Random mating * Infinite population size * No selection * No mutation * No migration (gene flow)

Question 32

What can cause deviations from the Hardy-Weinberg equilibrium?

Answer 32

* Inbreeding * Assortative mating * Small population sizes * Genetic drift * Evolution

Question 33

What is sexual selection?

Answer 33

A selection factor influencing evolution based on mate choice

Question 34

What is Fisher's hypothesis?

Answer 34

A theory related to sexual selection, female preference for a specific male trait can lead to an exaggerated development of that trait in males. This happens because females are more likely to mate with males possessing the preferred trait.

Question 35

What is artificial selection?

Answer 35

Selection driven by human choice rather than natural processes

Question 36

What is inbreeding depression?

Answer 36

Reduced biological fitness due to breeding between closely related individuals

Question 37

What is gene flow?

Answer 37

The movement of alleles from one population to another

Question 38

What is a mutation?

Answer 38

A change in the DNA sequence of an organism

Question 39

Give an example of a mutation (selected for in zoos)...

Answer 39

•Leucism in tigers- Hinderance in the wild