Genetics and Populations

Question 1

Define Diploid

Answer 1

A cell or organism that has a pair of homologous chromosomes

Question 2

What is a gene?

Answer 2

A sequence/section of DNA that codes for a particular protein

Question 3

Define Allele?

Answer 3

A version of a gene

Question 4

What is a Genotype?

Answer 4

The combination of alleles within an organism

Question 5

What is a phenotype?

Answer 5

The physical expression of a genotype

Question 6

What does it mean if an allele is dominant?

Answer 6

An allele that is always expressed

Question 7

What is a recessive allele?

Answer 7

It is only expressed when homozygous

Question 8

What results from co dominance?

Answer 8

Both alleles are expressed in the phenotype

Question 9

What is the locus?

Answer 9

The position of a gene on a chromosome

Question 10

What is dihybrid inheritance?

Answer 10

Inheritance of 2 characteristics controlled by separate genes

Question 11

What is the expected phenotypic ratio of the F2 generation?

Answer 11

9:3:3:1

Question 12

What is monohybrid inheritance?

Answer 12

Inheritance of characteristics controlled by a single gene

Question 13

What percentage of a F1 generation would be heterozygous?

Answer 13

100%

Question 14

What is the expected retail of genotypes in the F2 generation?

Answer 14

1:2:1

Question 15

What would be the expected percentage of different phenotypes in the F2 generation?

Answer 15

3:1 (75% to 25%)

Question 16

What is epistasis?

Answer 16

An interaction between genes where the expression of one gene suppresses the expression of another gene

Question 17

What is an autosome?

Answer 17

Any chromosome that is not a sex chromosome eg) 44 autosomes

Question 18

How are autosomes linked?

Answer 18

If they are on the same autosome they will stay together during independent segregation - meaning they will be inherited together

Question 19

How does autosomal linkage affect phenotypic ratios?

Answer 19

Because they are inherited together more offspring have the same phenotype as their parents

Question 20

What else can affect autosomal linkage?

Answer 20

Cross over

Question 21

Species

Answer 21

A group of similar organisms that can breed and produce fertile offspring

Question 22

Population

Answer 22

All the organisms of a single species in one place at the same time

Question 23

Community

Answer 23

All organisms in one place in one time

Question 24

Gene pool

Answer 24

All the alleles present in a population

Question 25

Allele frequencies

Answer 25

How common the allele is

Question 26

Evolution

Answer 26

Change in allele frequencies over time

Question 27

Differential reproductive success

Answer 27

Organisms with a phenotype better adapted to their environment have a selective advantage, more likely to survive breed and pass on their genes

Question 28

Speciation

Answer 28

The formation of a new species

Question 29

What are the predictions of Hardy-Weinberg principles?

Answer 29

The frequency of alleles of a gene will stay constant over generations

Question 30

What assumptions are made for a Hardy Weinberg calculation?

Answer 30

No mutation takes place No selection Random mating Large population No genetic drift Population is genetically isolated

Question 31

What is intraspecific variation?

Answer 31

Individuals of the same species have the same genes but different alleles (phenotypes)

Question 32

What is interspecific variation?

Answer 32

Individuals of different species have different genes/ live in different environments ( have different phenotypes)

Question 33

Define continuous variation. What graph would be used?

Answer 33

Variation is smooth/ continuous eg) height/weight Line graph

Question 34

Define discontinuous variation. What graph would be used?

Answer 34

Individuals fall into discrete groups with no intermediates eg) blood groups Bar chart

Question 35

Why would discontinuous variation take place?

Answer 35

It is controlled by a single gene or a few alleles

Question 36

What are genetic causes of variation?

Answer 36

Mutation Meiosis (cross over/ independent assortment) Random fertilisation

Question 37

What are environmental examples of variation?

Answer 37

Accent Siamese cat fur ( sensitive to temp.)

Question 38

What are examples of both genetic and environmentally caused variations.?

Answer 38

Height Both nutrition and genetics

Question 39

What is speciation?

Answer 39

The forming of a new species

Question 40

What is allopatric speciation?

Answer 40

Speciation caused by geographic isolation

Question 41

What is sympatric speciation?

Answer 41

Not geographically isolated but are reproductively isolated Eg) morphological, seasonal, behavioural, hybrid sterility

Question 42

How does speciation occur?

Answer 42

There is no gene flow between/ within the population(s) Variation exists in the population(s) due to mutation There are different selection pressures (allopatric) This results in directional selection of phenotypes There is differential reproductive success Over several generations there is a change in allele frequencies

Question 43

What is genetic drift?

Answer 43

Change in allele frequencies over time, caused by random chance and is not reliant on environment Eg ) random fertilisation Affects small populations

Question 44

Describe directional selection

Answer 44

Caused by a change to environment The extreme phenotype is selected for Eg) antibiotic resistance

Question 45

Describe stabilising selection

Answer 45

The mean of the Pop. is selected for Eg) birth weight

Question 46

Describe disruptive selection

Answer 46

Both phenotypic extremes are selected for Contributes to sympatric speciation

Question 47

What is abundance?

Answer 47

The number of individuals of a single species in and ecosystem

Question 48

What is distribution?

Answer 48

Where an organism is found in an ecosystem/ habitat

Question 49

What is intraspecific competition?

Answer 49

Competition within a species, individuals occupy the same niche so compete for food, mates and shelter etc)

Question 50

What is the carrying capacity?

Answer 50

The maximum stable pop an ecosystem can support

Question 51

Define limiting factor

Answer 51

The thing that limits pop. size

Question 52

Define interspecific competition

Answer 52

Competition between different species Between species that have similar niches

Question 53

Define niche.

Answer 53

The role an organism plays in an ecosystem

Question 54

What may result of complete niche overlap

Answer 54

One would either die or adapt

Question 55

What results from partial niche overlap?

Answer 55

Interspecific competition

Question 56

What type of organisms are studied using transects or quadrats?

Answer 56

Slow moving or stationary organisms eg) plants

Question 57

What type of sampling is a transect used for?

Answer 57

Systematic

Question 58

Describe a line transect

Answer 58

Run tap between two points and record all species that touch the tape

Question 59

Describe a belt transect

Answer 59

Use quadrats along the length of the transect

Question 60

Describe an interrupted transect

Answer 60

Quadrats are used at fixed intervals along the transect

Question 61

What is a quadrat

Answer 61

A square frame - can be divided into squares

Question 62

What does mud can easily cover solid concrete stand for?

Answer 62

Migration, colonisation, establishment, competition, stabilisation, climax

Question 63

Equation for population size (mark release recapture method)

Answer 63

(total caught 1st x total caught in second sample)/ total recaptured