BIOL 3620 exam 2

Human populations are polymorphic for the gene coding for myoglobin, with two alleles, A1 and A2. Tomoya Takata and his colleagues (Takata et al. 2002) found that in a small Japanese population, the frequency of the A1 allele was 0.755. If the population is in Hardy-Weinberg equilibrium, what are the frequencies of the A1A1, A1A2, and A2A2 genotypes, respectively?

0.57, 0.37, 0.06

In a population of birds, wing feather pigmentation is determined by a single gene with two incompletely dominant alleles, A1 and A2. Suppose genotype A1A1 confers dark brown wings, genotype A1A2 is light brown, and genotype A2A2 is light beige. In a population of 1000 birds, 350 have dark brown wings, 500 have light brown wings, and 150 have light beige wings. What is the A1 allele frequency in this population?

0.60

If one human protein contains 400 amino acids, how many nucleotides need to be in the exons of the corresponding gene to properly code for it?

1200

In a population of about 50 walruses with 30 fertile females, only 4 males are mating, due to strong male-male competition. Suppose that you need to provide data for conservation efforts and are asked to calculate the effective population size (Ne). What would be your best estimate?

14

The figure shows the genealogical history of gene copies in a population. How many generations back do these gene copies coalesce?

7

According to the narrator of the inbreeding video, how many deleterious (harmful) recessive alleles are carried by the average person?

800

An addition or deletion of one or two base pairs in a gene sequence results in a __________ mutation.

frameshift

In selection experiments on quantitative traits, we often measure a value of the response to selection (R). What is R equal to?

h^2*S

The major genetic effect of inbreeding in a population is to increase the number of__________.

loci at which the average individual is homozygous

In sickle cell anemia, a point mutation leads to a replacement of one amino acid in a hemoglobin molecule, in a unit responsible for transportation of oxygen. This and any other mutation in a gene that causes a change in the amino acid sequence in a polypeptide chain is known as a __________ mutation.

missense

The proportion of phenotypic variance that results from additive genetic variance alone is called the __________ heritability.

narrow-sense

Which of the following lists four factors that can cause or create linkage disequilibrium in a population?

natural selection, migration, mutation, and genetic drift

In the southern European plains, a species of flower comes in two colors, purple and pink. When pink flowers are most common in a field, bees visit and pollinate the purple flowers more often, and vice versa. This switching of pollinator preference will result in __________.

negative frequency-dependent selection

Under Hardy-Weinberg equilibrium, which of the following is true?

p = 1 - q

What allele frequencies result in the highest frequency of heterozygotes in a population at Hardy-Weinberg equilibrium? Correct!

p = q = 0.5

In quantitative genetics theory, the value of a quantitative trait is sometimes given by the equation P = G + E. We could define P as the _________ of the continuous trait that we are studying.

phenotypic value

Which of the following breaks up or removes linkage disequilibrium from a population?

sexual reproduction

When narrow-sense heritability is calculated using similarities between parents and offspring, it will correspond to the __________.

slope of linear regression between the average phenotype of the two parents and the phenotype of the offspring

According to the neutral theory, most mutations are deleterious and most _______________ are __________.

substitutions; neutral

In the figure, the green and gold boxes represent the offspring of parents that are heterozygous at locus 1 (Aa) and locus 2 (Bb). Which of the boxes represent repulsion double heterozygote offspring?

the green boxes

How did Hopi Hoekstra test of differences in the survivorship of different colored mice?

Clay mice

Which position in a codon shows the greatest degeneracy? In other words, if a change occurs in this codon position, it is less likely to change the amino acid that is specified relative to the other positions.

third position

A mutation that results in a replacement of a purine with a pyrimidine is known as a __________ mutation.

transversion

A mouse population contains hybrids between New Zealand Black (NZB) and New Zealand White (NZW) mice. NZW homozygotes are healthy, but NZB homozygotes experience autoimmune disease. NZB/NZW heterozygotes experience even more severe autoimmune disease (so much so that they are used as a model for the human autoimmune disease lupus). This situation is an example of __________.

underdominance

What was the name of the fossil marine reptile found high in the Andes mountains?

Kronosaur

According to the video, what was the most likely cause of the extinction of the pterosaurs?

Large size

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

Mating in the population is not random with respect to the locus in question.

Genetic drift tends to increase the homozygosity of a population, and if it were the only evolutionary process operating, any finite population would eventually become entirely homozygous. In practice, however, populations do not become entirely homozygous. Why not?

New mutations provide a continual supply of new genetic variation.

One important consequence of genetic drift is that it decreases the heterozygosity in a population from what is expected under Hardy-Weinberg equilibrium.What are the observed and expected heterozygosities in a population that has three genotypes with the following frequencies f(A1A1) = 100, f(A1A2) = 25, f(A2A2) = 100.

Observed = 0.1; Expected = 0.5

Which of the following was the ancestor of the vertebrates?

Pikaia

A mutation in DNA that does not change the protein produced is known as a _____________ Mutation.

Synonymous

The graph shows the changes in allele frequencies in simulations of 10 replicate populations. Which of the following is a reasonable explanation for what happened to these populations around generation 100 (highlighted in blue)?

The population size decreased.

Manx cats are common on a remote island near Great Britain, though rare elsewhere. They have a reduced or absent tail and longer hind legs than forelegs. This phenotype is caused by a dominant allele, M, at an autosomal locus. Manx cats are always Mm heterozygotes because MM homozygotes are aborted prenatally. What is the best evolutionary explanation for the Manx cats' prevalence on this island?

The prevalence of the Manx phenotype on this island is a result of the founder effect and genetic drift.

What is the difference between the situations shown in the red and yellow lines?

The red line shows a dominant allele; the yellow line shows a recessive allele.

The figure illustrates correlations by twin type and sex in a study of the influence of genetics on depression. Monozygotic twins (MZ) develop from one fertilized egg, whereas dizygotic twins (DZ) develop from two independent zygotes. Choose the correct statement based on the data.

There is a higher correlation for depression in monozygotic twins than in dizygotic twins, and therefore, depression may have a genetic component.

What is an important difference between transmission genetics and population genetics?

Transmission genetics deals with genotypes of individuals, while population genetics deals with genotype frequencies in a population.

Complex eyes have evolved multiple times in diverse organisms over the course of evolutionary history.

True

One factor that may have driven the evolution of diversity in the Cambrian (the Cambrian Explosion) was the rise of visual predators.

True

Trilobites are extinct.

True

In a recent study on fitness consequences of antipredatory behavior and coloration pattern in garter snakes (Thamnophis ordinoides), the phenotype space was depicted as a three-dimensional graph where the highest points represent combinations of traits associated with the greatest fitness values. For such situations, we could use Sewall Wright's metaphor of the __________.

adaptive landscape

In the Genetic Drift video, which organisms were used to illustrate the effect of random mortality on populations?

ants

Which three lineages evolved a heart?

arthropods, molluscs and vertebrates

What element is bound by proteins in the blood of arthropods and molluscs (instead of iron)?

copper

One of the important facts learned from experiments in molecular genetics is that most amino acids can be encoded by more than one nucleotide triplet. For this reason, we say that the genetic code is __________.

degenerate

A mutation resulting in deletion of a protein-coding gene will most likely have a ___________ effect on fitness.

deleterious

In mice that are homozygous for the dark-color Agouti allele (D), the effects of the Mc1R locus are entirely masked so that, irrespective of the genotype at Mc1R, the mice have fully dark coloration. However, if at least one copy of the light-color Agouti allele (L) is expressed, the different shades of brown Mc1R locus are revealed (with the particular shade depending on the number of copies of L). This is an example of __________.

epistatic effects of the two genes

Consider three loci experiencing different selective conditions. Assuming the same initial number of gene copies and constant population size, which locus will have the longest time to coalescence?

A locus under balancing selection

Which statement is FALSE regarding populations that have experienced a bottleneck?

Allele frequencies in a population are almost always very similar before and after a bottleneck.

Suppose that you collected genotype frequency data from a natural population. If you found that the expected genotype frequencies differed significantly from your observed genotype frequencies, which of the following could you conclude?

At least one evolutionary process is operating in this population.

In their experiment in 1943 using E. coli, Salvador Luria and Max Delbrück tested two alternative hypotheses. The random mutation hypothesis and the acquired inherited resistance hypothesis make different predictions about the distribution of resistant mutants that will be observed upon exposure to bacteriophage (viruses that can infect and kill E. coli). Which of the following predictions, if proven, would support the acquired inherited resistance hypothesis?

At the time of exposure to the phage, all E. coli cells will be phage-sensitive. The process of exposure to the phage will induce phage resistance in a small fraction of the bacterial cells.

Which of the following is TRUE regarding the difference between a DNA molecule and an RNA molecule?

DNA is a double-stranded molecule, whereas RNA is a single-stranded molecule.

Galápagos lava lizards inhabit dry rocky areas and are found on numerous islands in this archipelago. Mark Jordan and Howard Snell (Jordan and Snell 2008) assessed the genetic diversity of 17 populations of lava lizards. They reasoned that in the absence of gene flow between populations, genetic drift should strongly influence the patterns of diversity at the 11 microsatellite markers that they sequenced. The figure summarizes their findings. Which of the following is the best interpretation of this graph?

Genetic drift has been operating more strongly in smaller populations.

What are the key characteristics required by teeth?

Hardness and toughness