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Biology > Populations and Evolution Word Stimulants > Flashcards

Populations and Evolution Word Stimulants Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Allele frequency

A

Number of times an allele occurs in a gene pool

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2
Q

Gene pool

A

Total of all the alleles of all the genes of a population

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3
Q

Hardy Weinburg principle purpose

A

Allele and genotype frequencies in a gene pool of a population remain constant
Generation to generation

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4
Q

Hardy Weinburg conditions

A

Not disturbed by different influences

Only possible in a lab (provides standard)

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5
Q

Disturbing influences

A 
Mutation
Genetic drift
Small population size
Gene flare
Non random mating
Selection
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6
Q

p + q = 1.0 (100%)

A

Used to calculate allele frequency
p - frequency of dominant
q - frequency of recessive

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7
Q

p^2 + 2pq + q^2 = 1.0 (100%)

A

AA + 2Aa + aa = 1.0

3 possible genotypes

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8
Q

Variation

A

Differences in characteristics between individuals

Same/different species

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9
Q

Continuous Variation

A

Variations spread over a range of measurements
All intermediates possible between 2 extremes
Eg Height
Distribution curve

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10
Q

Discontinuous variation

A

Distinct categories
Eg blood group
Bar Chart

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11
Q

Environmental causes of variation

A

Nutrients (food, minerals)
Drugs (serious effect on appearance)
Temperature (effects rate of enzyme-controlled reactions)
Physical training (more muscle used, increase in size/power)

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12
Q

Genetic causes of variation

A

Mutations

Meiosis events

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13
Q

Meiosis events - variation

A 
Homologous chromosomes (pair, independent assortment - segregate independently > daughter cells)
Sex cells (gametes) vary genetically - chromosome pairings
New parent allele combination in zygote (random mating/fertilisation) - genetically different offspring
Crossing over - recombination of chromosomes
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14
Q

Carrying capacity

A

Resources available enable population to survive in its niche

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15
Q

Fundamental niche

A

Resources available to a species in the absence of competition

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16
Q

Realised niche

A

Resources available to a species in the outcome of competition

17
Q

Natural selection

A

Mechanism of evolution

18
Q

Natural Selection steps

A

Individuals vary genetically (characteristics slightly different)
Limited resources
Advantageous alleles/characteristics favoured for - better compete for resources, better adapt, more likely to survive & reproduce (offspring inherit)
Favourable alleles/characteristics accumulate in population
Descendent allele frequency different to ancesteral
Specialisation

19
Q

Competition

A

Stop over production
Species equilibrium - carrying capacity of niche
Niche sets upper capacity
Realised niche
More intense = greater selection pressure = increases rate of divergence

20
Q

Divergence

A

Races > subspecies > species

21
Q

Speciation

A

Formation of new species
Result of natural selection
Outcome of evolution

22
Q

Measuring rate of evolution

A

Measure change of allele frequency in one population

23
Q

Selection pressure

A

Change in environment

Stimulates evolution

24
Q

Evolution

A

Change over time

Change in allele frequency

25
Q

Stabilising selection

A

Stable environment
Low selection pressure
Extremes selected against
Close to average selected for - more likely to reproduce (pass on alleles)
Species change very little - maintains consistency; descendent look like ancestors

26
Q

Directional selection

A 
Rapidly changing environment
High selection pressure
Selection pressure favours individuals with adaptation (pass on alleles)
Long term trend = new species
New species arise quickly
Descendent do not look like ancestors
27
Q

Disruptive selection

A

Variety of selection pressures in an environment
Both extremes selected for - co existing of species (polymorphic)
Average selected against
Two new species form

28
Q

Isolating mechanisms

A

Divergence of gene pools

29
Q

Deme

A

Separated components of a single population
Encounter and respond to slightly different circumstances of fragmented environment (adapt through natural selection over time > speciation)

30
Q

Allopatric Speciation

A

Geographical separation (demes isolated)
Meeting and mating interrupted (free flow of genes restricted)
Demes respond to their environment (selection pressures)
Deme allele frequencies change (different to pool genes of other demes)
Divergence from original population
New species

31
Q

Sympatric speciation

A 
Same environment
Isolated
Cannot interbreed/ not exchanging alleles
Free flow of population interrupted
Divergence > new species

Biology (25 decks)

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