Genetic Variation

Question 1

What is the order of Meiosis?

Answer 1

1. Cell Replicates 2. Crossing Over 3. Independent Assortment 4. Segregation

Question 2

What is a chromatid?

Answer 2

One copy of replicated DNA

Question 3

What is complete dominance?

Answer 3

When one allele is fully dominant over the other e.g. pure black rabbit

Question 4

What is incomplete dominance?

Answer 4

When both alleles are partially expressed (black + white = grey)

Question 5

What is co-dominance?

Answer 5

When both allele phenotypes are equally expressed e.g. white with black spots all over

Question 6

What are homologous chromosomes?

Answer 6

The position of the gene is the same on each chromosome

Question 7

What is independent assortment?

Answer 7

The way the homologous chromosomes line up at the equator of the cell

Question 8

What is crossing over?

Answer 8

Occurs during meiosis, when the homologous chromosomes line up at the equator, sometimes they tangle, snap and exchange genetic
information.

Question 9

What is segregation?

Answer 9

The process that occurs during meiosis where pairs of alleles are separated when the homologous chromosomes split

Question 10

Describe what multiple alleles are and give an example?

Answer 10

Multiple alleles is when there are more than two alleles exist. E.g. human blood types with 3 alleles although a healthy human only inherits 2

Question 11

What is natural selection?

Answer 11

The process by which heritable traits increase an organism’s chances of survival and reproduction.

Question 12

What is allele frequency?

Answer 12

It represents the occurrence of a particular allele within a gene pool and it is a reflection of the genetic diversity of a population

Question 13

Define Genetic variation

Answer 13

The presence of differences in genetic material between individuals within a species

Question 14

Define Genetic Drift

Answer 14

The change in the frequency of an existing gene variant (allele) in a population due to random chance alone and not natural selection.

Question 15

What can cause genetic drift?

Answer 15

Population Bottleneck and Founders effect

Question 16

What is the bottleneck effect?

Answer 16

Is an event that drastically reduces the size of a population, may be caused by various events, such as an environmental disaster.

Question 17

How does population bottleneck effect genetic variation?

Answer 17

Genetic variation / allele frequency in a population is affected by genetic bottleneck through loss of alleles.

Question 18

How does genetic bottleneck affect a small populations?

Answer 18

In a small population, genetic drift can have a larger proportional effect on allele frequencies/ genetic variation

Question 19

How does genetic bottleneck effect large populations?

Answer 19

In a large population, genetic drift/ bottleneck is less likely to lead to alleles becoming fixed /lost due to the buffer effect of the larger number of individuals.

Question 20

What are linked genes?

Answer 20

Genes located on the same chromosome that tend to be inherited together

Question 21

What is a mutation?

Answer 21

A permanent change in the bases on the DNA. It is the only way of creating new alleles

Question 22

What kinds of mutations are there?

Answer 22

Gametic and Somatic. Gametic can be passed onto offspring. Somatic cannot.

Question 23

Why might harmful mutations accumulate more in small populations than a larger population?

Answer 23

They might accumulate more due to a small number of individuals breeding. With limited numbers of individuals, the mutation is easily passed on.

Question 24

What is the founder effect?

Answer 24

Is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population and/or are reproducibly isolated from the original population and/or subjected to different reproductive pressures

Question 25

What is evolution?

Answer 25

It is the change in the characteristics of a species over several generations
and relies on the process of natural selection.

Question 26

What is a gene?

Answer 26

A length of DNA that holds the instructions for a characteristic

Question 27

What is the gene pool?

Answer 27

It refers to the total number of genes of every individual in a population

Question 28

Define Heterozygous

Answer 28

When different forms of an allele are present e.g. Hh

Question 29

Define Homozygous

Answer 29

When the same form of an allele is present e.g. HH or hh

Question 30

Define lethal genes

Answer 30

Alleles that produce a gene product that kills the offspring

Question 31

Define Migration

Answer 31

Movement of organisms into (immigration) and out (emigration)of a
population.

Question 32

What is selective pressure?

Answer 32

Can take many forms, including environmental conditions, availability of food and energy sources, predators, diseases, and even direct human influence.

Question 33

What effect does genetic bottleneck have on a population?

Answer 33

The population bottleneck produces a decrease in the gene pool of the population because many alleles, or gene variants, that were present in the original population are lost.

Question 34

What does a bottleneck do to a population?

Answer 34

This results in an unrepresentative gene pool from the original population

Question 35

What does a bottle neck do to genetic variation?

Answer 35

Bottleneck results in lowered genetic variation /low number of differing alleles in a
population.

Question 37

What is more likely to happen to smaller population effected by bottleneck?

Answer 37

They are more likely to have alleles becoming fixed, lost or reduced in variation