Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BI158 > Chapter 23 > Flashcards

Chapter 23 Flashcards

1
Q

When is evolution apparent?

A

in changes in a population over time, not individual animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is microevolution? (2)

A

change in allele frequencies in a population over generations

Evolution in its smallest scale

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the three main mechanisms of microevolution?

A

natural selection

genetic drift

gene flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does natural selection differ from genetic drift and gene flow in regards to microevolution?

A

The only mechanism that consistently improves the match between organisms and the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is genetic drift?

A

chance events that alter allele frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is gene flow?

A

transfer of alleles between population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is genetic variation?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does genetic variation differ with the amount of genes?

A

Single gene- either-or effect is produced (purple or white flowers)

two or more genes- produces a difference in gradations along a continuum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is gene variation quantified?

A

the average percentage of loci that are heterozygous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can gene variation be measured in the molecular level?

A

nucleotide variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why doesn’t nucleotide variation always result in phenotypic variability?

A

differences occur within introns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are five sources of genetic variation?

A

Mutation

Gene duplication

Production of new alleles and genes

Sexual reproduction

Produced rapidly by organisms with short generation times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does new alleles arise?

A

mutation, or change in nucleotide sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Can mutations be predicted?

A

Cannot be predicted how and which DNA will be altered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where does mutations occur, and how can it be passed down?

A

The majority of mutations occur in somatic cells in animals

Only mutations in gametes can be passed to offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is point mutation, and an example?

A

change in one base

Ex- sickle cell disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How beneficial or harmful are mutations?

A

Most mutations are slightly harmful

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is heterozygote protection?

A

when heterozygous individuals mask harmful recessive alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is neutral variation?

A

point mutations in introns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does gene duplication occur? (3)

A

Error in mitosis

Slippage during DNA replication

Activities of transposable elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When are gene duplications harmful?

A

Large duplications can be harmful

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How can small amounts of gene duplication affect genetic variation?

A

Smaller duplication may persist over generations and allow mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How is gene duplication correlated with evolution, and an example?

A

Played a major role in evolution

human ancestors had only one gene to smell, now we have 350

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can prokaryotes evolve quickly?

A

Prokaryotes have lower average mutations but have such more generations that variations arise quickly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why is HIV so hard to cure?

A

HIV mutates even more quickly since it has short generation times and RNA genome, making Single-drug treatment is less effective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does gene variation arise from sexual reproduction?

A

Gene variation results from combination of alleles from parents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Methods during sexual reproduction where gene variation arises (3)

A

Crossing over

Independent assortment of chromosomes

fertilization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is a population, and how are they separated?

A

a group of individuals of the same species that live in the same area and interbreed to produce fertile offspring

isolated from others geographically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is a gene pool?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What does a gene pool characterize?

A

Characterizes a population’s genetic makeup

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is frequency proportion?

A

number of specific allele/number of all allele x 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is a fixed allele?

A

an allele existing for a particular locus in a population- all individuals are homozygous for this allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the Hardy-Weinberg equilibrium? (2)

A

a population that is not evolving

Allele and genotype frequencies will remain constant from generation to generation- only if Mendelian segregation and recombination of alleles at work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the Hardy-Weinberg equation?

A

P2 (homozygous dominant) + 2pq (heterozygous) + q2 = 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How does the Hardy-Weinberg equation signify equilibrium?

A

The actual population of homozygous dominant must equal p2 and so on for the population to be in equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are the conditions for Hardy-Weinberg equilibrium? (5)

A

no mutation

random mating

no natural selection

extremely large population size

no gene flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What happens if conditions of the Hardy-Weinberg equilibrium is not met?

A

evolution occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

How does mutation allow evolution?

A

A gene pool is modified if mutations alter alleles or if entire genes are deleted or duplicated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How does non-random mating allow evolution?

A

If individuals mate within a subset population, such as inbreeding, random mixing of gametes does not occur, and genotype frequencies change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How does natural selection allow evolution?

A

Differences in survival and reproductive success of individuals carrying different genotypes can alter allele frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How does a small population size allow evolution?

A

The smaller the population, the more likely allele frequencies will fluctuate by chance from one generation to the next- aka genetic drift

42
Q

How does gene flow allow evolution?

A

Moving alleles into or out of populations, gene flow can alter allele frequencies

43
Q

How is the Hardy-Weinberg Equation applied?

A

in medicine

ex- Estimating % of the population carrying alleles for inherited diseases like PKU

44
Q

What does not alter allele frequency? (2)

A

New mutations

non-random mating

45
Q

Why doesn’t new mutations alter allele frequencies?

A

Mutations are rare, so change is small

46
Q

Why doesn’t non-random mating alter allele frequencies?

A

Non-random mating can alter frequencies of homo/heterozygous, but not allele frequencies in the gene pool

47
Q

What is natural selection based on?

A

differential success in survival and reproduction

48
Q

What is natural selection?

A

Individuals exhibit variations in charitable traits, and traits more suited to the environment often produce more offspring

49
Q

What does natural selection result in?

A

alleles being passed in proportions that differ

50
Q

What is adaptive evolution?

A

an evolution that results in a better match between organisms and their environment

51
Q

What is genetic drift?

A

chance events causing allele frequencies to fluctuate unpredictably from one generation to the next

52
Q

What is genetic drift common in?

A

small populations

53
Q

What is an example of genetic drift?

A

white flowers being accidentally killed, leading to less white-flowered offspring

54
Q

What increases chance of deviation from predicted results?

A

The smaller the number of events that occur

55
Q

What is does small population lead to?

A

over/underrepresentation of an allele in the next generation

56
Q

What two things can genetic drift cause?

A

allele frequencies to change at random

harmful alleles to become fixed

57
Q

What can genetic drift lead to?

A

loss of genetic variation within populations

58
Q

What is the founder effect?

A

when few individuals become isolated from a larger population, a smaller group can establish a new population with a different gene pool

59
Q

What does the founder effect account for?

A

a high frequency of certain inherited disorders in isolated human populations

60
Q

What is the bottleneck effect?

A

a sudden change in environment, like a flood, drastically reducing the size of the population

61
Q

What is gene flow?

A

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

62
Q

What can gene flow result in?

A

two populations combining into a single population with a common gene pool

63
Q

What can natural selection increase?

A

frequencies of alleles that provide reproductive advantage

64
Q

What is relative fitness?

A

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

65
Q

What does relative fitness act on?

A

more directly on the phenotype than on the genotype

66
Q

What does selection favor?

A

heritable phenotypic traits that provide higher reproductive success

67
Q

What is directional selection?

A

when conditions favor individuals exhibiting one extreme of a phenotypic range

68
Q

What is a directional selection frequency curve?

A

Shifts the population’s frequency curve of phenotypic character in one direction or the other

69
Q

When is directional selection common, and an example?

A

Common when the environment changes or when members migrate to a new habitat

Ex- Galapagos finches

70
Q

What is disruptive selection?

A

when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes

71
Q

What is an example of disruptive selection?

A

two beak sizes in one species

One for soft seeds, the other for hard seeds

Medium-sized beaks are inefficient in feeding on both

72
Q

What is stabilizing selection?

A

acts against both extreme phenotypes and favors intermediate variants

73
Q

What does stabilizing selection reduce?

A

Reduces variation and tends to maintain the status quo of a phenotype

74
Q

What is an example of stabilizing selection?

A

baby weight, with smaller and larger weights having higher mortality

75
Q

How does adaptations arise?

A

gradually as natural selection increases frequencies of alleles that enhance survival and reproduction

76
Q

What kind of process is adaptive evolution, and why?

A

Since the environment changes over time, adaptive evolution is a continuous dynamic process

77
Q

How does genetic drift affect adaptive evolution?

A

can both increase and decrease beneficial allele frequency

78
Q

How does genetic flow affect adaptive evolution?

A

introduce both advantageous and disadvantageous alleles

79
Q

What is sexual selection?

A

natural selection which individuals with certain inherited characteristics are more likely than other individuals to obtain mates

80
Q

What is sexual dimorphism, and examples (2)?

A

difference in secondary sexual characteristics between males and females of the same species

Ex- size, color, ornamentation, behavior

81
Q

What is intrasexual selection, and what is it common in?

A

selection within the same sex, competing directly for mates of the opposite sex

Common in males

82
Q

What is intersexual selection, and what is it common in?

A

individuals of one sex being choosy in selecting their mates from the opposite sex

Often in female

83
Q

Why did female preferences evolve? (2)

A

Female preferences for certain male characteristics may have evolved because the traits are correlated with good genes

“Attractive” male traits may be related to overall health as well

84
Q

Why can’t natural selection cut all unfavorable alleles?

A

because recessive alleles are hidden in heterozygotes

85
Q

What is balancing selection?

A

selection preserving variation at some loci, maintaining two or more forms in a population

86
Q

What does balancing selection include?

A

Includes heterozygote advantage and frequency-dependent selection

87
Q

What is heterozygote advantage?

A

when heterozygotes have greater fitness than either kind of homozygotes

88
Q

How does natural selection correlate with heterozygote advantage?

A

Natural selection tends to maintain two or more alleles at certain loci

89
Q

What is heterozygote advantage defined in?

A

terms of genotype

90
Q

What kind of selection is heterozygote advantage?

A

Either a stabilizing or direction selection, depending on phenotype advantage

91
Q

What is an example of heterozygote advantage?

A

sickle cell

Heterozygotes are protected from the severe effects of malaria

92
Q

What is frequency-dependent selection?

A

fitness of a phenotype depends on how common it is in the population

93
Q

What is an example of frequency-dependent selection?

A

scale eating fish oscillate between right and left mouths in response to prey guarding against the specific side

94
Q

How does natural selection operate?

A

on a “better than” basis

95
Q

Four reasons why natural selection cannot fashion perfect organisms

A

Selection can act only on existing variation

Evolution is limited by historical constraints

Adaptations are often compromises

Chance, natural selection, and the environment interact

96
Q

How does natural selection act on existing variation?

A

Favors only the fittest phenotype currently in the population, which may not be the ideal trait

97
Q

How is evolution limited by historical constraints?

A

Evolution only operates on traits an organism only has, working on existing structure

98
Q

What is an example of adaptation compromise?

A

flexible limbs allow versatility, but make us prone to sprains, torn ligaments, and dislocation

99
Q

How does chance and natural selection interact, and an example?

A

Chance events affect the evolution of the population

Ex- storm can transport insects to an unfavorable environment

100
Q

How does the environment and natural selection interact?

A

The environment at a location can change unpredictably from year to year

BI158 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions