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Biology A level > 4.4 Variance and evolution > Flashcards

4.4 Variance and evolution Flashcards

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1
Q

What is the definition of variance?

A

Differences within a species

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2
Q

What are the characteristics of discontinuous variation?

A

Discrete grouping (e.g. blood type)
controlled by a single gene

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3
Q

What are the characteristics of continuous variation?

A

Continuous grouping
controlled by a number of genes (polygenetic)
influenced by environment

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4
Q

What is assumed when using the t-test?

A

Sample size is suitable
Sample is normally distributed

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5
Q

How does sexual reproduction produce genetic variation?

A

Independent assortment of chromosomes
crossing over during prophase 1
mixing of parental genotypes

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6
Q

What is a gene pool?

A

Total number of alleles for all genes in a population

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7
Q

What is genetic drift?

A

a change in allele frequencies in a population from generation to generation that occurs due to chance events

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8
Q

Why do genetic frequencies change?

A

Genetic drift
mutation
Natural selection (selection pressure)

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9
Q

What is selection pressure?

A

When an organisms environment determines the spread of alleles within a gene pool

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10
Q

What is the bottle neck effect?

A

reduced gene frequency caused by a natural disaster

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11
Q

What is the founder effect?

A

A few individuals from a population start their own population with varied allele frequency to the original population

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12
Q

What issues can arise with the founder effect?

A

Non representative group
Inbreeding causing health issues

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13
Q

What group is an example of the founder effect?

A

Pennsylvania Amish

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14
Q

What is an example of selection pressure?

A

MRSA

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15
Q

What are the similarities between bottlenecking and the founder effect?

A

followed by genetic drift
initial loss of biodiversity
small circle of breeding (inbreeding)
Untrue ratio of alleles to gen pop

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16
Q

What are the differences between bottlenecking and the founder effect?

A

Bottlenecking reduces choice of mates due to death whilst founders are geographically separated

17
Q

What is allopatric speciation?

A

Different groups of the same species are geographically isolated

18
Q

What is sympatric speciation?

A

reproductive barriers arising with in a population as a result of natural selection

19
Q

What are isolation mechanisms?

A

Factors that prevent gene exchange between the population

20
Q

What are some examples of isolation mechanisms?

A

Geographical features
habitat changes
behavioural changes
morphology changes
breeding mechanism changes

21
Q

What are some examples of how sympatric speciation occurs?

A

morphological isolation (sex organ variation)
seasonal isolation (time of maturity)
Gametic isolation (gametes incompatible)
hybrid inevitability
hybrid sterility

22
Q

What is hardy Weinberg’s assumption?

A

The frequency of alleles and genotypes will remain the same

23
Q

What are the conditions of the Hardy Weinberg equation?

A

No natural selection
no mutation
No Migration
Random mating
Large population size

24
Q

What is the Hardy Weinberg equation?

A

p^2 + 2pq + q^2 = 1
p + q = 1

25
Q

What is a niche?

A

An species role in its environment

26
Q

What is natural selection?

A

fitter individuals who are betted adapted to the
environment survive and pass on the advantageous genes to future generations

27
Q

What is evolution?

A

the frequency of alleles in a gene pool changes over time as a result of natural selection

28
Q

What is speciation?

A

new species arise after a population becomes separated and cannot interbreed

29
Q

What is a species?

A

A group of organisms with similar morphological and physiological features that able to breed together and produce fertile offspring

30
Q

What is p^2 in the Hardy Weinberg equation?

A

Homozygous dominant (AA)

31
Q

What is q^2 in the Hardy Weinberg equation?

A

Homozygous recessive (aa)

32
Q

What is 2pq in the Hardy Weinberg equation?

A

Heterozygous (Aa)

Biology A level (15 decks)

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