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Biology Revision Year 2 > Genetics and Populations > Flashcards

Genetics and Populations Flashcards

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1
Q

Define Diploid

A

A cell or organism that has a pair of homologous chromosomes

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2
Q

What is a gene?

A

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

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3
Q

Define Allele?

A

A version of a gene

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4
Q

What is a Genotype?

A

The combination of alleles within an organism

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5
Q

What is a phenotype?

A

The physical expression of a genotype

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6
Q

What does it mean if an allele is dominant?

A

An allele that is always expressed

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7
Q

What is a recessive allele?

A

It is only expressed when homozygous

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8
Q

What results from co dominance?

A

Both alleles are expressed in the phenotype

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9
Q

What is the locus?

A

The position of a gene on a chromosome

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10
Q

What is dihybrid inheritance?

A

Inheritance of 2 characteristics controlled by separate genes

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11
Q

What is the expected phenotypic ratio of the F2 generation?

A

9:3:3:1

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12
Q

What is monohybrid inheritance?

A

Inheritance of characteristics controlled by a single gene

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13
Q

What percentage of a F1 generation would be heterozygous?

A

100%

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14
Q

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

A

1:2:1

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15
Q

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

A

3:1 (75% to 25%)

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16
Q

What is epistasis?

A

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

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17
Q

What is an autosome?

A

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

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18
Q

How are autosomes linked?

A

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

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19
Q

How does autosomal linkage affect phenotypic ratios?

A

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

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20
Q

What else can affect autosomal linkage?

A

Cross over

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21
Q

Species

A

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

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22
Q

Population

A

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

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23
Q

Community

A

All organisms in one place in one time

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24
Q

Gene pool

A

All the alleles present in a population

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25
Q

Allele frequencies

A

How common the allele is

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26
Q

Evolution

A

Change in allele frequencies over time

27
Q

Differential reproductive success

A

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

28
Q

Speciation

A

The formation of a new species

29
Q

What are the predictions of Hardy-Weinberg principles?

A

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

30
Q

What assumptions are made for a Hardy Weinberg calculation?

A

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

31
Q

What is intraspecific variation?

A

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

32
Q

What is interspecific variation?

A

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

33
Q

Define continuous variation. What graph would be used?

A

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

34
Q

Define discontinuous variation. What graph would be used?

A

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

35
Q

Why would discontinuous variation take place?

A

It is controlled by a single gene or a few alleles

36
Q

What are genetic causes of variation?

A

Mutation Meiosis (cross over/ independent assortment) Random fertilisation

37
Q

What are environmental examples of variation?

A

Accent Siamese cat fur ( sensitive to temp.)

38
Q

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

A

Height Both nutrition and genetics

39
Q

What is speciation?

A

The forming of a new species

40
Q

What is allopatric speciation?

A

Speciation caused by geographic isolation

41
Q

What is sympatric speciation?

A

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

42
Q

How does speciation occur?

A

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

43
Q

What is genetic drift?

A

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

44
Q

Describe directional selection

A

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

45
Q

Describe stabilising selection

A

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

46
Q

Describe disruptive selection

A

Both phenotypic extremes are selected for Contributes to sympatric speciation

47
Q

What is abundance?

A

The number of individuals of a single species in and ecosystem

48
Q

What is distribution?

A

Where an organism is found in an ecosystem/ habitat

49
Q

What is intraspecific competition?

A

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

50
Q

What is the carrying capacity?

A

The maximum stable pop an ecosystem can support

51
Q

Define limiting factor

A

The thing that limits pop. size

52
Q

Define interspecific competition

A

Competition between different species Between species that have similar niches

53
Q

Define niche.

A

The role an organism plays in an ecosystem

54
Q

What may result of complete niche overlap

A

One would either die or adapt

55
Q

What results from partial niche overlap?

A

Interspecific competition

56
Q

What type of organisms are studied using transects or quadrats?

A

Slow moving or stationary organisms eg) plants

57
Q

What type of sampling is a transect used for?

A

Systematic

58
Q

Describe a line transect

A

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

59
Q

Describe a belt transect

A

Use quadrats along the length of the transect

60
Q

Describe an interrupted transect

A

Quadrats are used at fixed intervals along the transect

61
Q

What is a quadrat

A

A square frame - can be divided into squares

62
Q

What does mud can easily cover solid concrete stand for?

A

Migration, colonisation, establishment, competition, stabilisation, climax

63
Q

Equation for population size (mark release recapture method)

A

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

Biology Revision Year 2 (13 decks)

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