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Biology 171 > Exam #2 > Flashcards

Exam #2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

when does crossover happen

A

prophase 1 of meiosis

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2
Q

what results from crossover?

A

recombinants AND nonrecombinants

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3
Q

recombinants

A

result of crossover, the physical exchange of parts of homologous chromosomes

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4
Q

genetic map

A

diagram showing the relative position of genes along a chromosome

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5
Q

map unit

A

the distance between genes resulting in 1% recombination

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6
Q

when distances are less than 15 map units…

A

the map distances between adjacent genes can be added to get the distance between the genes at the ends

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7
Q

when distances are more than 15 map units apart…

A

the observed recombination frequency is somewhat smaller than the sum of the map distances between genes

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8
Q

epistasis

A

MULTIPLE genes affect phenotype; pliotropy = 1 gene MULTIPLE phentotypes

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9
Q

Harmful mutations are often eliminated in one or a few generations because

A

they decrease the survival and the capacity to reproduce of those affected

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10
Q

genotype-by-environment interaction

A

combination of homozygous (genes) and smoking (environment)

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11
Q

For X & Y sex chromosomes, reciprocal crosses…

A

are not equivalent

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12
Q

sex chromosomes

A

X and Y chromosomes

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13
Q

autosomes

A

chromosomes that are NOT sex chromosomes

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14
Q

X is ____(size)___ than Y

A

X is LONGER than Y

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15
Q

Regions of homology on tips of chromosomes…

A

allow pairing during meiosis (crossover)

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16
Q

Segregation of the sex chromosomes predicts…

A

a 1:1 ratio of females to males

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17
Q

who discovered x linked genes

A

Morgan; genetics of fruit flies

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18
Q

“wild type”

A

most common phenotype

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19
Q

Criss cross inheritance:

A

An X chromosome present in a male in one generation must be transmitted to a female in the next generation, and in the generation after that can be transmitted back to a male

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20
Q

Linked

A

genes that are close together in the same chromosome & do NOT assort INDEPENDENTLY

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21
Q

nonrecombinants

A

alleles are present in the same combination as the parent

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22
Q

crossover

A

the physical exchange of parts of homologous chromosomes, prophase 1 of meiosis

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23
Q

the frequency of recombination is a measure of…

A

the genetic distance between linked genes

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24
Q

if 2 genes are so close together that crossing over never takes place…

A

we would expect only nonrecombinant chromosomes

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25
Q

if 2 genes are located very far apart from each other..

A

1 or more crossovers will occur, and there will be a 1:1:1:1 ratio of nonrecombinant and recombinant gametes

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26
Q

maximum frequency of recombination

A

50%

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27
Q

natural selection results in…

A

allele frequencies changing from generation to generation according to the allele’s impact on the survival and reproduction of indiviuals

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28
Q

What did Malthus point out in his Essay on the Principle of Population?

A

natural populations have the potential to increase in size geometrically, meaning that populations get larger at an ever-increasing rate (does not actually happen doe)

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29
Q

fitness

A

a measure of the extent to which the individual’s genotype is represented in the next generation (reproduction)

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30
Q

paraphyletic

A

a group that includes a common ancestor and SOME but not all of its descendents

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31
Q

polyphyletic

A

group of organisms that does not include a common ancestor

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32
Q

taxa

A

tips of the branches that are groups of organisms

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33
Q

sister groups

A

two groups that are closest relatives bc they share a common ancestor not shared by any other group

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34
Q

speciation

A

the set of processes by which physically, physiologically, or ecologically isolate populations diverge from one another to the point where they can no longer produce fertile offspring

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35
Q

taxonomy

A

to recognize and name groups of individuals as species, and to group close species into more inclusive taxonomic group

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36
Q

phylogenetics

A

aims to discover the pattern of evolutionary relatedness among groups of species by comparing their anatomical or molecular features

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37
Q

phylogenetic tree

A

hypothesis about the evolutionary history of species

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38
Q

genus (plural: genera)

A

closely related species grouped together

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39
Q

taxonomic classification order

A

genus > family > order > class > kingdom >domain

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40
Q

characters

A

the anatomical, physiological, or molecular features that make up organisms

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41
Q

character states

A

several observed conditions

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42
Q

character states in diff. species can be similar for 1 of two reasons:

A

the character state was present in the common ancestor of the two groups and retained over time (common ancestry), OR the character state independently evolved in the two groups as an adaptation to similar environments (convergent evolution)

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43
Q

analogous

A

similarities due to independent adaptation by diff species (result of convergent evolution)

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44
Q

what is used in constructing phylogenetic trees?

A

only homologies

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45
Q

synamorphies

A

shared derived character

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46
Q

cladistics

A

phylogenetic reconstruction on the basis of synamorphies

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47
Q

parsimony

A

choosing the simpler of two or more hypotheses to account for a given set of observations

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48
Q

the extent of similarity (or distance) indicates…

A

how recently 2 groups shared a common ancestor

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49
Q

single gene traits

A

each one is determined by variation at a single gene and the traits for the most part are not influenced by environment

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50
Q

complex traits

A

(such as human height) influenced by multiple genes as well as by the environment…found in all organisms…important in human health and disease…phenotype determined by measurement

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51
Q

environmental risk factor

A

a characteristic in a person’s surroundings that increases the likelihood of developing a particular disease

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52
Q

inbred lines

A

true-breeding strains (homozygous)…often used for research

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53
Q

complex traits are affected by (one/many) genes

A

many

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54
Q

phenotypes of many complex traits show ___ distribution

A

normal

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55
Q

complex traits

A

both genetic factors and environmental factors contribute to variation in phenotype among individuals

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56
Q

norm of reaction

A

for any genotype graphically depicts how the environment (x axis) affects phenotype (y axis) across a range of environments

57
Q

heritability

A

the proportion of the total variation due to genetic differences among individuals

58
Q

when heritability is 100%…

A

slope of the line is 1; average phenotype of the offspring from any pair of parents will = the average phenotype of the parents themselves

59
Q

when heritability is 0%…

A

the line representing the trait has a slope of 0. the average phenotype of offspring will be = to the average of the population as a whole, despite the phenotypes of parents

60
Q

cultural transmission

A

some environmental effects in phenotype (ex: rich parents = rich kids)

61
Q

Single nucleotide polymorphism (SNP)

A

site in the genome where either of two different nucleotide pairs can occur and where each nucleotide pair is common enough in the population to be present in a random sample of 50 diploid individuals …AKA single base changes in individuals

62
Q

positive selection

A

natural selection that increases the frequency of a favorable allele

63
Q

negative selection

A

natural selection that decreases the frequency of a deleterious allele

64
Q

stabilizing selection

A

maintains status quo and acts against extremes (ex: human birth weight must be between both extremes) …keeps a trait the same over time (extremes are eaten)

65
Q

directional selection

A

leads to a change in a trait over time (finches and their bills size for food) (skewed right or left)

66
Q

artificial selection

A

form of directional selection…analogous to natural selection but the competitive element is removed

67
Q

disruptive selection

A

operates in favor of extremes and against intermediate forms (apple maggot flies) (middle is eaten)

68
Q

sexual selection

A

promotes traits that increase an individual’s access to reproductive opportunities

69
Q

intrasexual selection

A

male vs male to get the girl

70
Q

intersexual

A

not fighting, just compete for attention with bright colors and displays. IN THIS CASE, FEMALES CHOOSE

71
Q

migration, mutation, genetic drift, and non random mating..

A

cause allele frequencies to change, but do NOT lead to adaptations

72
Q

migration

A

movement of individuals from one population to another…results in gene flow (decrease pop’s average fitness…ex: white ppl going to the equator and getting sunburn and skin cancer)

73
Q

gene flow

A

the movement of alleles from one pop. to another

74
Q

mutation (increases/decreases) genetic variaton

A

increases; source of new alleles and the raw material on which other forces act…RARE

75
Q

genetic drift

A

random change in allele frequencies from generation to generation

76
Q

bottleneck

A

originally large pop. falls to just a few individuals (loss of genetic variation)

77
Q

founder event

A

when a few individuals start a new population (small number of peeps arrive on an island and colonize it) (genetic variation is lost)

78
Q

genetic drift has a large effect in…

A

small populations

79
Q

why does nonrandom mating alter genotype frequencies without affecting allele frequencies???

A

it just rearranges alleles already in the gene pool and, unlike migration or mutation, does not add new alelles to the population

80
Q

most evolutionarily significant form of non-random mating

A

inbreeding (increases the freq. of homozygotes and decreases the # of heterozygotes in a pop. without affecting allele frequencies)

81
Q

The modern synthesis

A

combines mendelian genetics and darwinian evolution…several genes contribute to a trait

82
Q

population genetics

A

the study of patterns of genetic variation

83
Q

species

A

individuals that can exchange genetic material through interbreeding…a group of individuals capable of sharing alleles with one another

84
Q

gene pool

A

different combos of alleles drawn from the species (human gene pool..skin color, hair type, eye color, etc)

85
Q

populations

A

interbreeding groups of organisms of the same species living in the same geographical area

86
Q

2 sources of genetic variation

A

mutation and recombination

87
Q

somatic

A

body’s tissues

88
Q

germ line

A

occurring in reproductive cells and then passed on to the next generation

89
Q

allele frequency of an allele x is…

A

number of x’s present in the pop. divided by total number of alleles

90
Q

fixed

A

population that exhibits only one allele at a particular gene

91
Q

3 ways to measure genotype and allele frequencies in populations:

A

observable traits, gel electrophoresis, and DNA sequencing

92
Q

@ genetic levels, evolution is simply…

A

a change in the frequency of an allele or a genotype from one generation to the next

93
Q

5 hardy weinburg equilibrium conditions

A
  1. no natural selection 2. no migration 3. no mutation 4. large sample (no genetic drift) 5. non-random mating
94
Q

allele frequencies…

A

p + q = 1 (are p and q)

95
Q

genotype frequencies

A

p^2 + 2pq +q^2 (use for hardy weinburg) (each part)

96
Q

species

A

groups of interbreeding populations that are reproductively isolated from other such groups

97
Q

morphospecies concept

A

members of the same species usually look alike (shape, size, coloration)

98
Q

probz with BSC

A

easier in concept than practice, does not apply to asexual (bacteria) or extinct organisms, ring species and hybridization complicate it

99
Q

ring species

A

species with populations that are reproductively but not genetically isolated (because of gene flow)

100
Q

hybridization

A

interbreeding (capable of exchanging genes with other species in their genera) …occurs mainly in plants

101
Q

prezygotic isolating factors:

A

behavioral, gametic, mechanical, temporal, geographic/ecological

102
Q

behavioral isolation

A

individuals mate only with other individuals based on courtship rituals, songs, or other behaviors (chimpanzees dont like humans)

103
Q

gametic isolation

A

incompatibilities between the gametes of 2 diff species (plants)

104
Q

mechanical incompatibility

A

genetalia (insects and animals)

105
Q

temporal isolation

A

time; diff. times of year…or active only during day/night

106
Q

geographic or ecological isolation

A

space. subtle. (bugs on specific plants)

107
Q

postzgotic isolation factors:

A

genetic incompatibility

108
Q

genetic incompatibility

A

genetic dissimilarity (diff # of chromosomes)

109
Q

the more closely related/genetically similar a pair of species…

A

the less extreme the genetic incompatibility between their genomes

110
Q

partially reproductively isolated

A

2 pops that have genetically diverged but not far enough for full reproductive isolation (speciation)

111
Q

allopatric speciation

A

speciation that results from GEOGRAPHICAL separation of populations

112
Q

subspecies

A

allopatric populations that haven’t evolved into speciation but have acquired population-specific traits

113
Q

how does allopatric speciation occur

A

dispersal and vicariance

114
Q

dispersal

A

some individuals colonize a distant place (like an island) far from the main source population

115
Q

vicariance

A

geographic barrier arises within a single population, separating it into two or more isolated populations

116
Q

peripatric speciation

A

specific kind of allopatric speciation where a few peeps from mainland disperse to a new location REMOTE from the original peeps and evolve separately (dispersal)

117
Q

adaptive radiation

A

unusually rapid evolutionary diversification in which natural selection accelerates the rates of both speciation and adaption

118
Q

co-speciation

A

occurs in response to speciation in another species (parasites)

119
Q

sympatric populations

A

not genetically separated…DISRUPTIVE SELECTION

120
Q

instantaneous speciation

A

caused by hybridization between 2 species in which the offspring are reproductively isolated from both parents (sympatric)

121
Q

double diploid is called a…

A

tetraploid

122
Q

polyploidy

A

multiple chromosome sets

123
Q

allopolyploids

A

polyploids that are produced from hybridization of two diff species

124
Q

autopolyploids

A

polyploids derived from an unusual reproductive event

125
Q

reinforcement of reproductive isolation (reinforcement)

A

process by which diverging populations undergo natural selection in favor of traits that enhance prezygotic isolation, thereby preventing the production of less fit hybrid offspring (mating discrimination)

126
Q

A mutation can go to fixation by selection if…

A

it is advantageous and by genetic drift

127
Q

primates

A

mammals that share a # of features: nails rather than claws, front facing eyes, and opposable thumbs

128
Q

humans closest relative is___

A

the chimpanzees

129
Q

human and chimpanzee dna differ by just ___%

A

1% (King and Wilson)

130
Q

hominins

A

species that have arisen on the human side of the human/chimpanzee split (ARDI)

131
Q

bipedal

A

moving w/ 2 feet and walking upright – LUCY

132
Q

first homonin

A

homo ergaster

133
Q

neanderthals

A

EUROPE AND MIDDLE EAST

134
Q

multiregional hypothesis

A

modern humans derive from h. ergaster that spread around the world 2 mya

135
Q

out-of-africa hypothesis

A

modern humans arose from h. ergaster in africa before going to africa around 60K y.a

136
Q

Cann’s ___

A

mtDNA

137
Q

Cro-Magnon

A

first known pop. of homo sapiens in europe

138
Q

explain why mtdna and the whole genome study may differ

A
  1. diff. patterns of transmission between mtDNA and genomic material (mtDNA from mama only) OR 2. ancient DNA stems from a sex-based difference in interbreeding (neanderthals were male)
139
Q

neoteny

A

long term evolutionary process in which the timing of development is altered so that a sexually mature organism still retains the physical chracteristics of juvenile form

Biology 171 (2 decks)

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