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Biology 111 > Chapter 23 > Flashcards

Chapter 23 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Natural selection acts on the

A

individuals

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2
Q

The effects of natural selection

A

evolution

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3
Q

effects (evolution) of natural selection are seen at the

A

population level

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4
Q

Genetic variation

A

differences among individuals in the composition of their genes or other DNA sequences

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5
Q

differences among individuals in the composition of their genes or other DNA sequences

A

Genetic variation

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6
Q

Genetic code (genotype)

A

determines the physical expression of a trait (phenotype)

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7
Q

determines the physical expression of a trait (phenotype)

A

Genetic code (genotype)

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8
Q

What plays a role in phenotypic expression?

A

Environment

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9
Q

What is a product of genotype and environmental factors

A

Phenotype

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10
Q

What is phenotype the product of?

A

The product of genotype and environmental factors

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11
Q

Sources of genetic variation

A
  1. Formation of new alleles
  2. Altering gene number or position
  3. Rapid reproduction
  4. Sexual reproduction
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12
Q

Mutations

A

change the nucleotide sequence

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13
Q

change in the nucleotide sequence

A

mutations

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14
Q

Mutations that result in new phenotypes tend to be…

A

maladaptive and are removed by natural selection

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15
Q

What are harmful recessive traits masked by?

A

heterozygote protections

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16
Q

Where do neutral mutations occur?

A

in non-coding regions (neutral variation)

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17
Q

Redundancy of genetic code

A

a source of neutral variation

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18
Q

a source of neutral variation

A

redundancy of the genetic code

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19
Q

Population

A

a group of organisms of the same species occurring in the same place at a given time

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20
Q

a group of organisms of the same species occurring in the same place at a given time

A

population

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21
Q

Microevolution

A

change in allele frequencies in a population over generations

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22
Q

change in allele frequencies in a population over generations

A

Microevolution

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23
Q

Where does microevolution occur?

A

The population level

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24
Q

What causes adaptive evolution

A

natural selection

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25
Q

genotype

A

the genetic make up, or set of alleles, of an organism

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26
Q

the genetic make up, or set of alleles, of an organism

A

genotype

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27
Q

phenotype

A

the observable physical or physiological traits of an organism (determined by genotype)

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28
Q

the observable physical or physiological traits of an organism (determined by genotype)

A

phenotype

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29
Q

Gregor Mendel

A

Austrian monk that determined there are “units” of inheritance (now called genes)

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30
Q

Austrian monk that determined there are “units” of inheritance (now called genes)

A

Gregor Mendel

31
Q

Sexual reproduction

A

shuffles existing alleles into new combinations

32
Q

Types of sexual reproduction

A
  1. Independent Assortment
  2. Crossing over
  3. Fertilization
33
Q

Independent assortment

A

homologous chromosomes pair up randomly during meiosis (cellular division)

34
Q

homologous chromosomes pair up randomly during meiosis (cellular division)

A

Independent assortment

35
Q

Crossing over

A

genetic material is swapped (exchanged) during meiosis

36
Q

genetic material is swapped (exchanged) during meiosis

A

crossing over

37
Q

Fertilization

A

a number of mating opportunities exist within a population, resulting in joining of gametes with genetic background

38
Q

a number of mating opportunities exist within a population, resulting in joining of gametes with genetic background

A

fertilization

39
Q

a population’s genetic make up is characterized by describing its…

A

gene pool

40
Q

Gene pool

A

all copies of every type of allele at every locus in all members of the population

41
Q

all copies of every type of allele at every locus in all members of the population

A

gene pool

42
Q

Fixed allele

A

occurs if only one allele exists for a particular locus (all individuals are homozygous for the allele)

43
Q

occurs if only one allele exists for a particular locus (all individuals are homozygous for the allele)

A

fixed allele

44
Q

Tthe proportion of each allele in the gene pool?

A

allele frequency

45
Q

Allele frequency

A

the proportion of each allele in the gene pool

46
Q

Allele frequency remains constant from…

A

Generation to generation (no evolution)

47
Q

Conditions for Hardy-Weinberg Equilibrium

A
  1. No mutations
  2. Random mating
  3. No natural selection
  4. Extremely large population size
  5. No gene flow
48
Q

Mechanisms of evolution

A
  1. mutation
  2. non-random mating
  3. genetic drift
  4. gene flow
  5. natural selection
49
Q

Mutation (2)

A

a source of variation

50
Q

Random with respect to fitness

A

Mutation

51
Q

harmful mutations are…

A

phased out, beneficial alleles increase

52
Q

Since mutations rarely occur…

A

there is very little change in allele frequencies from generation to generation

53
Q

Non-random mating

A

occurs when individuals mate within a subset of the population

54
Q

Non-random mating my affect the frequencies of heterozygotes and homozygotes, but…

A

unless individuals with certain ingerited traits are more likely to obtain mates, allele frequencies are unchanged

55
Q

Examples of non-random mating

A

female mate choice and male-male competition

56
Q

When the probability of mating is not the same among individuals

A

Non-random mating

57
Q

Three major factors that alter allele frequencies and bring about most evolutionary changes

A
  1. natural selection
  2. genetic drift
  3. gene flow
58
Q

Genetic drift

A

unpredictable changes in allele frequencies dut to change alone (not by inherited trait)

59
Q

Genetic drift is random with respect to…

A

fitness

60
Q

Genetic drift occurs…

A

in every population in every generation

61
Q

Important points about genetic drift

A
  1. is random fluctuation in allele frequencies
  2. removes genetic variation from the population
  3. more powerful in small populations
62
Q

Founder Effect

A

a few individuals become isolated from the source population and differs genetically from the source

63
Q

Genetic Bottleneck

A

sudden reduction in population size (catastrophic event) results in drastic change in gene pool

64
Q

Gene flow

A

transfer of alleles into or out of a population due to the movement of fertile individuals or gametes

65
Q

Natural selection

A

differential success in reproduction results in certain alleles being passed to the next generation in greater proportions

66
Q

The only mechanism that consistentl causes adaptive evolution

A

Natural selection

67
Q

adds variation and can act antagonistically

A

gene flow

68
Q

removes variation and may or may not cause an increase in beneficial or harmful alleles

A

genetic drift

69
Q

Relative fitness

A

contribution an individual makes to the gene pool of the next generation relative to the contribution of other individuals

70
Q

Types (modes) of Natural Selection

A
  1. Directional selection
  2. Disruptive selection
  3. Stabilizing selection
71
Q

Directional selection

A

occurs when selection favors one extreme phenotype over another

72
Q

Disruptive selection

A

occurs when selection favors extreme phenotypes over intermediate phenotpes

73
Q

Stabilizing selection

A

occurs when selection favors intermediate phenotype over the extremes

Biology 111 (8 decks)

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