Brainscape's Knowledge GenomeTM

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


See full index

biology 109 > test 2 > Flashcards

test 2 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

phylogeny

A

history of evolutionary relationships

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

taxon (plural: taxa)

A

group of related organisms, species, genus, family, order, class; never populations

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

what does someone mean when they ask how closely related are they?

A

how much of their genomes do they share

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

the more nodes you and some species shares….

A

the more related you are

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

what strategy doesn’t work for reading evolutionary trees

A

counting nodes

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

(evolutionary trees) branches

A

lead to animals/other branches

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

(evolutionary trees) nodes

A

where branches connect

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

(evolutionary trees) animal species that was at a _____ is __________ of branches beyond them

A

node; ancestor

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

(evolutionary trees) T or F: flipping the order of branches doesn’t matter

A

true

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

(evolutionary trees) how can you tell how closely related two groups are?

A

by finding the closest (most recent) common ancestor

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

counting what the closest _____ is between 2 species while comparing 3 different ones can help figure out which 2 out of 3 are ____ _______ compared to the other one

A

node; “more related”

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

(evolutionary trees) zoonitic pathogen

A

one that has (+/- recently) jumped from animal to human

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

how many non-human species did HIV colonize humans from?

A

2

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

what do different branch lengths represent?

A

degree of differences (usually genetic)

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

genetic drift

A

evolution by luck

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

genetic drift states that change is still possible, why?

A

lucky (or unlucky) differences in individual reproductive success

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

even ______ alleles can change allele _________ unpredictably

A

neutral; frequencies

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

(neutral alleles) example of bad luck

A

accidental deaths, etc

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

(neutral alleles) example of good luck

A

extra offspring survive, etc

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

natural selection criterion (changed by genetic drift)

A

1) individuals are different 2) some variants have more offspring than others because of luck 3) individuals inherit their differences

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

what stays the same in neutral alleles?

A

same fitness and reproductive success; none better than others

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

if an allele is lost, what’s its frequency?

A

0

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

if an allele is fixed, what’s its frequency?

A

1

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

by genetic drift, ________ populations evolve more slowly than _________ ones

A

bigger; smaller

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

what does genetic drift lead to, whether in big/small populations?

A

loos/fixation of neutral alleles; new, neutral mutations arise (many exist at the same time)

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

diploids

A

2 chromosomes per individual –> 2 copies per parent –> double number of allele copies in population

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

what makes alleles not neutral?

A

they have different fitnesses

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

the most ____ allele is more likely to become fixed, but it’s not ____________

A

fit; guaranteed

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

advantageous allele

A

has higher fitness than other alleles

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

deleterious allele

A

has lower fitness than other alleles (s > 0)

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

neutral allele

A

same fitness as other alleles

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

selection coefficient

A

strength of selection against a trait/allele

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

selection coefficient formula

A

s= 1- fitness

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

what does someone mean when they say, “selection tips the scales”

A

even a deleterious allele can get lucky

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

what does selection depend on?

A

only on relative fitness

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

what does genetic drift depend on?

A

only on population size

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

when is natural selection “more efficient”?

A

in larger populations

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

what is implied when someone says “more efficient”?

A

more likely to produce the outcome predicted by fitness differences

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

T or F: drift has less effect in larger populations

A

true

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

it becomes harder to distinguish between selection and drift as…

A

selection gets weaker and population size stays the same AND when population size increases and selection rate stays the same

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

conservation biology

A

biological principles used for managing: species threathened with extinction, and habitats threatened with loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

population bottleneck

A

the rapid shrinking of a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

(population bottleneck) recovery

A

when populations grow to larger size again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what happens the longer it takes a population to recover from a bottleneck?

A

faster genetic variation is lost
population will less likely be able to adapt to environmental changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

fixed alleles have to wait for ______ ________ to form in order to adapt to new environments

A

new mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

evolutionary trap

A

population gets smaller –> deleterious alleles fixed faster –> population gets even smaller –> deleterious alleles fixed even faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

genetic rescue

A

escape the evolutionary trap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

genetic drift _____ and natural selection _____ tend to reduce genetic variation

A

always; often

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

mutation

A

changes alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

recombination

A

shuffles different loci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

meiosis

A

gamete formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

meiosis process

A

single cell: 2 copies of each chromosome –> DNA replication –> single cell: 4 copies of each chromosome –> cell divides –> 2 cells: 2 copies of each chromosome per cell –> cell divides again without DNA replication –> egg or sperm cells: 1 copy per cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

why is there variation in each row of a chromosome?

A

because each column is from a different individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

why are DNA sequences different?

A

because neutral polymorphism has accumulated in the population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

two gene-shuffling step

A

1) crossover; 2) different chromosomes randomly mixed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

(two gene-shuffling step) crossover

A

pieces of chromosomes switch places

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

how many pairs of chromosomes does a human have?

A

23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

chunks of chromosomes inherited from grandparents will become _______ into smaller and smaller ____ AND those chunks will be in (approximately) ________ sizes because crossing over is (approximately) ________

A

fragmented; pieces; random; random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

SNP

A

single-nucleotide polymorphism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

SNP map

A

locations of SNPs on chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

(genetic drift w neutral mutations/one locus) T or F: most new, neutral mutations are quickly lost

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

(genetic drift w neutral mutations/one locus) T or F: no loci are mutating

A

false; many loci arr always mutating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

(genetic drift w neutral mutations/one locus) T or F: two is the maximum number of alleles that can exist at a time at a locus; one must become fixed before a new one can arise

A

false; mutations don’t care if there’s variation and can happen anywhere/any time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

(genetic drift w neutral mutations/one locus) after a sufficiently long time, the fraction of ________ ________ on the DNA that are polymorphic will __________

A

neutral sites; stabilize

65
Q

(purifying selection on a beneficial mutation) what does it mean for deleterious alleles when new beneficial mutations are fixed?

A

they become lost

66
Q

(purifying selection on a beneficial mutation) when the beneficial alleles increase, _____________ ______ increase too

A

neutral alleles

67
Q

(purifying selection on a beneficial mutation) selective sweep

A

whole chunk of chromosome is fixed; other nearby chunks retain their polymorphism

68
Q

what probably occurred if an area has low polymorphism?

A

natural selection must’ve swept through –> “signature of selection”

69
Q

how can anybody “read” the DNA to find gene experiencing natural selection?

A

areas that have lost their polymorphism must have undergone recent selection

70
Q

human skin color is:

A

continuous

71
Q

rickets

A

calcium deficiency in bones

72
Q

what causes rickets?

A

vitamin D2 and D3 deficiency AND low calcium

73
Q

what does rickets lead to?

A

broken bones and malnutrition

74
Q

what does calcium do for the body?

A

mechanisms moving things in/out of cells and contracting muscles rely on calcium

75
Q

calcium deficiency

A

taking supply out of the bone and moving into the rest of the body –> rickety bones

76
Q

what is the cure for rickets?

A

increasing vitamins D2 and D3

77
Q

sources of vitamin D

A

diet: fish and meats
make our own: photosynthesis, hunter-gatherer cultures (high vitamin D), shift to agriculture (low vitamin D)

78
Q

UV light

A

a mutagen

79
Q

mutagen

A

cause of mutation

80
Q

when is a mutation formed?

A

when something is incorrectly repaired

81
Q

what can UV lights change?

A

base on DNA

82
Q

calcitriol

A

hormone controlling calcium flow in/out of cells

83
Q

where is UV light lowest at?

A

high latitudes

84
Q

where is UV light highest at?

A

near equator and in high mountains (low latitudes)

85
Q

where are the chances of getting skin cancer higher at?

A

low latitudes

86
Q

melanins

A

pigments that protect against UV light

87
Q

2 types of melanin

A

eumelanin and pheomelanin

88
Q

pigment cell

A

type of skin cell that contains melanin

89
Q

T or F: most cells don’t have melanin in them

A

true

90
Q

T or F: all cells are the same color

A

false

91
Q

melanosome

A

“ball of melanin” in a pigment cell

92
Q

what helps contribute to what color a person is/how much melanin they have in their body?

A

pigment cells and melanosomes

93
Q

what are the major genes with the biggest effects on skin pigmentation?

A

TYR (tyrosinase): starts melanin synthesis
IRF4 and TYRP1: control TYR activity
MC1R: controls pheomelanin branch
DCT: controls eumelanin branch

94
Q

2 major genes that help with melanosome formation and provisioning

A

OCA2 and TCNP2

95
Q

(melanosome formation and provisioning) OCA2

A

moves molecules (that are used to make melanin) into melanosomes; controls how many melanosomes a person makes

96
Q

(melanosome formation and provisioning) TCPN2

A

controls melanin synthesis through how many molecules (that make melanin) are made

97
Q

if pale skin evolved more than once, the _______ ________ in major pigmentation genes should be ________ in those populations (at least for neutral mutations)

A

point mutations; different

98
Q

what 6 major pigment genes have point mutations for indigenous East Asian and Europeans

A

TYR, DCT, TYRP1, MC1R, OCA2, KITLG

99
Q

what evolved independently in East Asia and Europe?

A

pale skin color

100
Q

when did pale skin evolve in Europe?

A

in Middle East ~14k years ago
in Europe ~4-5k years ago

101
Q

speciation

A

the origin of species; origin of new branches on evolutionary trees

102
Q

how to distinguish species in practice

A

look for distinct phenotypes/genotypes without intermediates

103
Q

why can phenotypes make distinguishing species hard?

A

cryptic species have very similar, easily confused phenotypes; not very ambiguous if you’re looking at the right thing

104
Q

how many different definitions are there of “species”?

A

72+ different species concepts; 3 or 4 major categories

105
Q

things “not different” enough to be species

A

subspecies, varieties, strains, ‘races’

106
Q

subspecies (animals)

A

population of the same species that look/is different in some way

107
Q

varieties

A

different habitats, different “looks”

108
Q

‘races’ (some insects)

A

not used by biologists; doesn’t have biological meaning in humans

109
Q

biological species concept

A

species are populations (or groups of populations) whose members are reproductively isolated from other such groups

110
Q

(animals and many plants) reproductively isolated

A

cannot (or won’t) share genes successfully; no gene exchange between them because no mating or hybrids are infertile/dead

111
Q

gene pools

A

alleles shared among individuals that can only interbreed among themselves –> they evolve independently

112
Q

(animals and many plants) speciation (BSC rephrased)

A

evolution of reproductive isolation (separate species evolve independently)

113
Q

(animals and many plants) hybridization

A

interbreeding between differentiated populations –> hybrids

114
Q

(animals and many plants) introgression

A

the spread of genes into another species

115
Q

(bacteria and archaeans) broad-sense “sex”

A

individuals steal or trade DNA from same and other bacterial strains; environmental DNA incorporated into chromosomes

116
Q

(bacteria and archaeans) horizontal gene transfer

A

genes passing between species

117
Q

(bacteria and archaeans) core genome

A

genes unique to each species

118
Q

(bacteria and archaeans) accessory gene

A

more readily shared, often define strains

119
Q

(bacteria and archaeans) what does horizontal gene transfer cause?

A

introgression

120
Q

(bacteria and archaeans) what are evolutionary trees more likely to do?

A

more likely to net (not clear branches)

120
Q

(bacteria and archaeans) what are evolutionary trees more likely to do?

A

more likely to net (not clear branches)

121
Q

(bacteria and archaeans) T or F: species evolve only partly independently

A

true

122
Q

separate species have different ecological roles, therefore…

A

occupy different niches

123
Q

(many plants and some animals) what do related species sometimes share?

A

genes

124
Q

(many plants and some animals) what do separate species have?

A

different ecological roles

125
Q

(many plants and some animals) species evolve ________ ______________

A

(partly) independently

126
Q

(many plants and some animals) speciation

A

evolution of new ecological role

127
Q

(how species evolve) ecological context

A

side-effect of adaptation to different conditions

128
Q

(how species evolve) geographic context

A

where populations are as speciation proceeds

129
Q

(how species evolve) evolution of reproductive isolation

A

many ways it can happen

130
Q

(how species evolve –> animals and many plants) what happens to hybrid species before they reach maturity?

A

they die or are infertile (even if offspring of “pure species” crosses are normal)

131
Q

(how species evolve –> animals and many plants) why do hybrids not make it long?

A

genes from the different species don’t interact properly

132
Q

(how species evolve –> animals and many plants) what do parents only “care” about?

A

their own reproductive success, not about the purity of their species (purity is a consequence of choosing high-quality mates)

133
Q

zygote

A

fertilized egg

134
Q

breakdown of life cycle

A

fertilization –> birth/hatching –> grow to maturity – egg/sperm reproduce –> egg and sperm find each other –> fertilization

135
Q

(breakdown of life cycle) postzygotic

A

between fertilization and egg/sperm reproducing

136
Q

(breakdown of life cycle) prezygotic

A

between egg/sperm production and fertilization

137
Q

(breakdown of life cycle) postzygotic reproductive isolation

A

hybrid dies/is sterile

138
Q

(breakdown of life cycle) postzygotic incomplete

A

hybrid has lower fitness

139
Q

Dobzhansky-Muller interactions

A

negative genetic interactions in hybrids

140
Q

(breakdown of life cycle) prezygotic reproductive isolation

A

egg and sperm never combine

141
Q

(breakdown of life cycle) prezygotic incomplete

A

sometimes combine

142
Q

Phylogenetic analysis of immunodeficiency virus strains in humans (HIV), apes (specifically, chimps and gorillas) and monkeys (SIV) indicates that:

A

HIV evolved from SIV when people were infected with SIV; Several SIV strains from different monkey and ape species independently
infected humans and evolved to become HIV

143
Q

Which is always true of ‘nodes’ on evolutionary trees, regardless of any other information that’s included in (or left out of) the tree?

A

Each node represents a single species (or strain) that gave rise to all the organisms on the branches that radiate from it

144
Q

Bats have a high diversity of coronaviruses. They also roost in colonies every night in close contact with one another. From an evolutionary perspective, based on this behavior of bats, what properties do you expect those coronavirus strains to have evolved in their native bat hosts?
a: In bats, the viruses are not likely to be very virulent – i.e., the symptoms should be mild or even asymptomatic.
b: In bats, the viruses are likely to be able to evade the immune system for a long time (or equivalently, they are likely to be able to re-infect bats that have built up immunity, just like SARS-CoV-2 can occasionally re-infect people who are vaccinated).
c: Both of the above.
d: Just the opposite of the above! In bats, the viruses should be especially highly
virulent just like it is in humans, and the bats that do survive will become permanently immune. Therefore, most bats in the wild should be well protected by their immune systems, and the viruses should be rare.

A

c

145
Q

T or F: Each of our 23 chromosomes is made up of a single, giant DNA molecule

A

true

146
Q

Every cell has the same DNA, so every time a cell divides, all of its DNA first has to be copied. In mammals (for example), what are the chances for a given base pair that copying introduces an error (a mutation)? (Genes typically have tens up to thousands of base pairs, so (if indeed there were errors) the rate would be higher for whole genes. This question is about base pairs.)
a: It doesn’t – DNA is copied pretty much perfectly every time. Every one of our cells has identical DNA.
b: Errors are very rare; on the order of 1 or 2 in a billion base pairs is mis-copied every time a cell divides.
c: Errors are unfortunately quite common, on the order of 1 in 1000 base pairs mis-copied, so each cell has thousands of mutations.

A

b

147
Q

For a virus to be able to attack a cell, that cell has to have a specific protein on its surface that the virus can attach to.
a: True, otherwise that cell can’t become infected. (Actually, some viruses attach to specific molecules that aren’t proteins.)
b: False; the virus does have to encounter a protein (or other molecule) on the cell surface, but cells have many kinds of surface proteins and the vast majority of them are vulnerable.

A

a

148
Q

Natural selection favors virus strains that can attach to cell-surface molecules (proteins, commonly) that are essential to the host organism.

A

True – the host can’t easily alter those molecules via mutation because they’re essential.

149
Q

The process of making proteins from information in mRNA molecules is called…

A

translation

150
Q

Which of these statements about the genetic code is TRUE? (Choose the best answer)
All organisms use the same code.
LUCA used the same genetic code that we do. Both the above are true.
None of the above is true.

A

both are true

151
Q

T or F: For natural selection to act on a protein, the mutation has to result in a change in its amino acid sequence

A

true

152
Q

T or F: All organisms have 61 different tRNA genes, each corresponding to a codon in the genetic code.

A

true

153
Q

The so-called “central dogma” of biology is that proteins are made using information from RNA, and in turn, RNA is made using information from DNA; copies of the DNA are made whenever cells divide.
Which of these statements is FALSE?
Copying DNA from DNA requires proteins.
Making RNA from information stored in DNA requires proteins.
Making proteins from information stored in RNA does not require proteins.
Trick question! They’re all true!

A

Making proteins from information stored in RNA does not require proteins.

154
Q

Can RNA act as an enzyme by catalyzing (promoting) chemical reactions?

A

Yes, but only some forms of RNA can do it.

155
Q

What seems likely to have been the cause of (or at least, a major contributor to) the Permian-Triassic extinction 250 million years ago, the largest of the mass extinctions?

A

global warming and volcanoes erupting

156
Q

Melanin is a molecule that arose early in the history of life, and a great many organisms can produce it. It plays many roles, including camouflage (animals matching their color to dark or light backgrounds), immune response (but only in insects), and of course

A

protection from mutation, because it absorbs ultraviolet light before it can cause damage to DNA

157
Q

Now that people can obtain Vitamin D through dietary supplements, alleles that produce light-colored skin have become …
deleterious
neutral
beneficial

A

deleterious

158
Q

So far, there isn’t enough DNA data to figure out how different shades of dark skin have evolved, though at this early stage, it appears likely that natural selection in the not-too-distant past (say, within the last 15,000 years) has led to an increase in average skin pigmentation in more than one region on earth. But we do know that within that same 15,000 year period, lighter colored skin has evolved?

A

twice for sure

biology 109 (3 decks)

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