Exam 2

Question 1

What allows HIV to evolve inside a patient?

Answer 1

HIV has a high mutation rate

Question 2

HIV-1 is believed to have been transmitted to humans from which of the following organisms?

Answer 2

Chimpanzees

Question 3

HIV-1 Group M is responsible for 95% of human infections. When is it estimated that HIV-1 Group M was transferred to humans?

Answer 3

1930

Question 4

Which of the following helped discredit the hypothesis that the Oral Polio VAccine program (OPV) helped spread HIV in central Africa?

Answer 4

Phylogenies indicate that divergence of human strains of HIV-1 predated OPV

Question 5

What evidence supports the claim that UN Blue Helmets from SE Asia inadvertently introduced cholera to Haiti in 2010?

Answer 5

The 2010 Haitian strain was nested within the SE Asian clade of cholera strains

Question 6

Phylogenetic trees can always be regarded as ____ about evolutionary relationships

Answer 6

Hypotheses

Question 7

A derived character that is shared among two or more lineages and their common ancestor is also called a(n)

Answer 7

Synapomorphy

Question 8

The wings of bats and birds and the streamlined body form of sharks and whales represents examples of

Answer 8

convergence

convergent evolution

Question 9

Comparing DNA sequences from living taxa and calibrating their rates of change with at least one well-dated fossil allows scientists to create time-calibrated trees with age estimates for all branch points. Such studies are called

Answer 9

molecular clock

Question 10

What are some assumptions that must be made before applying a molecular clock model to estimate time of divergence?

Answer 10

Substitution rate is constant across related lineages and nucleotide sequence undergo neutral evolution.

Question 11

The estimated phylogeny of CAnine Transmissible Veneran Tumor provides strong evidence that

Answer 11

Infected dogs transmit CTVT cells

Question 12

The ability of Daphnia pulex to grow protective armor upon sensing chemicals produced by the predatory phantom midge is an example of

Answer 12

environmental variation

Question 13

The differential response in hemoglobin production across human populations from montane and non-montane regions is an example of

Answer 13

Genotype X environment variation

Question 14

The patterns of phenotypes an individual may develop upon exposure to different environments is called its

Answer 14

reaction norm

Question 15

A hypothetical population has two alleles for a gene: A and a. In a random sample of 50 individuals, 20 are homozygous for A, 20 are homozygous for a and 10 are heterozygous (Aa). What is the frequency of A?

Answer 15

AA 40/100=0.4
aa 40/100=0.4
Aa 10/100=0.1
0.1+0.4=0.5. 50%

Question 16

In DNA, the substitution of a purine for a purine or a pyrimidine for a pyrimidine is called a(n)

Answer 16

transition

Question 17

In DNA, the introduction of a stop codon before the end of coding sequence is called a(n)

Answer 17

nonsense mutation

Question 18

Genes that are derived from a common ancestral sequence, and are separated by a speciation event such as the RNASE1 gene in douc langur monkeys and the RNASE1 gene in humans, are described as

Answer 18

orthologous genes

Question 19

Genes that are duplicated within a genome and later diverge in function such as the RNASE1 and RNASE1B genes in douc langur monkeys are described as

Answer 19

paralogous genes

Question 20

Frequencies of inversions and/or allele frequencies often vary regularly when examined over a geographic area changing in either latitude or climate. This type of regular change is called a

Answer 20

cline

Question 21

Organisms with more than two chromosome sets are said to be

Answer 21

polyploidy

Question 22

If 40 mice have genotype Hh in a population of 100 mice, what will be the frequency of Hh individuals after 10 generations if the population is in HWE?

Answer 22

40%

Question 23

If a population is in HWE which of the following statements is correct?

Answer 23

allele frequencies must remain the same from generation to generation

Question 24

In large populations, the HWE principle can be used to determine whether evolution is occuring. For instances where allelic frequencies are indicated by p and q, the resultant genotype frequencies are indicated by which of the following equations?

Answer 24

p^2 + 2pq + q^2

Question 25

Consider the case of a lethal recessive allele present in a natural population at low frequency (i.e., q=0.05_, and is not conferring any fitness advantage to heterozygotes. How quickly will this lethal recessive allele become lost from the population?

Answer 25

Very slowly, because as q approaches 0, q/(1+q) will approach q

Question 26

Why is genetic drift more important in small populations?

Answer 26

Because sampling error is higher in small populations than it is in large populations

Question 27

You are studying genetic structure in a population of 16 Florida panthers, 10 males and 6 females, What is the effective population size, Ne, in this population?

Answer 27

Ne=4*10*6/(10+6)=15

Question 28

The theory of neutral evolution describes

Answer 28

the rate of fixation of alleles at a site in the absence of selection

Question 29

When dN?dS

Answer 29

scientists would reject the null hypothesis of neutral evolution because the number of replacement substitutions is greater than expected

Question 30

What type of selection is most likely responsible for the large antlers seen on male elk, or the enlarged claws in male fiddler crabs?

Answer 30

Intrasexual selection

Question 31

Parental care by males

Answer 31

results in sexual selection on females

Question 32

The Red Queen Hypothesis

Answer 32

refers to the fact that host immune systems evolve continuously and quickly in an arms race with parasite populations that are also evolving to evade their defenses

Question 33

Are unequal gamete sizes relevant for explaining adult behavior? Why or Why not?

Answer 33

es, there are typically insufficient eggs to go around; males end up having to compete for access to the eggs

Question 34

The generally deleterious effects caused by inbreeding are due to

Answer 34

an increase in homozygosity of recessive deleterious alleles

Question 35

alleles that are relatively new to a population and have been subject to strong positive natural selection are characterized by having

Answer 35

high frequency and high linkage disequilibrium

Question 36

The Atlantic cod is a diploid organism. In a sample of 50 specimens drawn from a trawl catch, all the individuals were genotyped for the polymorphis locus Hbl, which codes for hemoglobin and has two alleles F and S: Calculate the percentage deviation form expected heterozygosity under Hardy Weinberg F=1-Hobs/Hexpected

Answer 36

F= 1-(16/50) / [2*(7/50)*(27/50)] = -111%

Question 37

A population of reindeer is in Hardy-Weinberg equilibrium for a gene for nose color, in which having a red nose is determined by a recessive allele. A population geneticist named Sandy Claws finds 64 red-nosed reindeer in his flock of 100. What is the frequency of the recessive allele.

Answer 37

0.8

Question 38

Assuming Hardy-Weinberg equilibrium, the genotype frequency of heterozygotes, if the frequency of the two alleles at the gene being studied are 0.8 and 0.2, will be:

Answer 38

0.32

Question 39

Which of the following is an example of homoplasy?

Answer 39

the independent origin of similar traits in separate lineages, the evolution of wings in both bats and birds, the reversion of a derived character state to its ancestral state

Question 40

In the equation for Hardy-Weinberg Equilibrium, what does p2 refer to?

Answer 40

Proportion of homozygous dominant genotypes

Question 41

The point at which the rate that a deleterious allele is being eliminated from a population by natural selection is in equilibrium with the rate at which the deleterious allele is being replaced by a new mutation is termed ________

Answer 41

mutation-selection balance

Question 42

the graph that has a ___ best shows the molecular clock assumption

Answer 42

positive slope

Question 43

Genes that are duplicated within a genome and later diverge in function, such as the RNASE1 and RNASE1B genes in douc langur monkeys, are described as

Answer 43

paralogous genes

Question 44

a derived character that is shared between an ancestor and all its descendants is called a(n)

Answer 44

synapomorphy

Question 45

In aposematic organisms, the allele frequencies of bright color morphs varied such that when predators associate bright colors with toxicity, the survival of brightly colored individuals further increases, leading to positive reinforcement, in a process known as

Answer 45

frequency-dependent selection

Question 46

Assuming an initial frequency of R, q = 0.1, what will happen to the frequency of q when the population of rats is exposed to warfarin?

Answer 46

q will increase in frequency and eventually will reach fixation`

Question 47

a population of 10 individuals has 20% heterozygosity, what is the expected % heterozygosity in the next generation as a result of genetic drift?

Answer 47

H'= 0.2(1-1/20)=0.19

Question 48

The principle of maximum parsimony discriminates among phylogenies on the basis of differences in

Answer 48

the number of inferred evolutionary changes

Question 49

The Hardy Weinberg Equilibrium states

Answer 49

in the absence of outside forces, frequencies of a population will not change over generations

Question 50

What sort of characters are useful in constructing phylogenetic trees?

Answer 50

homologous and shared derived traits

Question 51

In determining the evolutionary relationships of current species, one needs to

Answer 51

read "back" to nodes connecting species to determine common ancestry

Question 52

If a mutation produces a new deleterious recessive allele in a population, what is least likely to happen to the frequency of that allele?

Answer 52

Selection will quickly removed from the population

Question 53

Which of the following is NOT an assumption of the Hardy-Weinberg equilibrium principle?

Answer 53

Individuals can immigrate only from adjacent populations.

Question 54

Reaction norms refer to:

Answer 54

a genotype’s change in phenotype across a range of environments

Question 55

These figures show (a) the rate at which Salmonella typhi bacteria (causing typhoid fever) infiltrate culture mouse cells having different CFTR genotypes, including mutation delta-F508, which causes cystic fibrosis; and (b), the severity of typhoid fever outbreaks in 11 countries in Europe versus the frequency of mutation delta-F508 in each country. What is maintaining the high frequency of delta-F508 in these European countries?

Answer 55

Superior fitness of heterozygotes during outbreaks of typhoid fever.

Question 56

Synapomorphies among a group of species is evidence that

Answer 56

the species share an immediate common ancestor

Question 57

Under which conditions would you expect to find frequencies of the dominant allele, p, vary according to the curves shown in this graph? (u shaped curve)

Answer 57

selection against heterozygosity or underdominance

Question 58

The following genotypes are found in a population. What are the allele frequencies of A and a? AA: 54 Aa: 16 aa: 30

Answer 58

A= 0.62 and a = 0.38

Question 59

The frequency of allele IB for blood type B is extremely low among indigenous American people. For example, in one sample of 1000 Papago Indians from Arizona, there were 190 A and 810 O blood types. Alleles IA and IB are co-dominant, whereas allele IO is recessive. Because there are so few people with type B, you can ignore the frequency of IB . What are the best estimates of the frequencies of alleles IA and IO among Papago people?

Answer 59

p(A) = 0.1, p(B) = 0.9

Question 60

Researchers studied a population of butterflies and determined observed genotypes of locus C with alleles C and c for a 100 individuals. They then used Hardy-Weinberg to calculate the expected frequency of genotypes, as shown below. Use the chi-square test to test the hypothesis that the population is in Hardy Weinberg equilibrium for this locus. What is the chi-square and significance value, and is the population in Hardy-Weinberg equilibrium? genotypes CC Cc cc observed 18 24 58 expected 9 42 49 squared sums of diffs. 9 7.7 1.65

Answer 60

chi-square = 18.35, p <0.0001, The population is NOT in Hardy-Weinberg equilibrium

Question 61

In a population of 18 land snail Theba pisana, 6 are homozygous recessive and 3 are heterozygote for a neutral marker. What are the observed and expected frequencies for the heterozygote genotype?

Answer 61

H(obs) = 1/6 ; H(exp) = 2*(15/36)*(21/36) = 0.49

Question 62

Which of the following statements explains why animals are less likely than plants to speciate by polyploidy?

Answer 62

animals rarely self-fertilize so diploid gametes are much less likely to fuse

Question 63

Which of the following statements about genetic recombination is FALSE?

Answer 63

Genetic recombination is relatively unimportant to the process of natural selection