Deck 18: Evolutionary Medicine

Question 1

The idea that within-host selection favors higher virulence assumes that

A) more rapidly replicating strains cause more damage to their hosts.
B) more rapidly replicating strains cause less damage to their hosts.
C) hosts evolve defenses against pathogens.
D) a and c
E) b and c

Answer 1

A

Question 2

The process of creating conditions in which viruses evolve reduced virulence is

A) attenuation.
B) resistance development.
C) serial passage.
D) vaccination.

Answer 2

A

Question 3

Which of the following viruses has/have jumped to humans from another species?

A) HIV
B) SARS
C) influenza
D) all of the above

Answer 3

D

Question 4

When a disease spreads across the globe this is known as a(n)

A) epidemic.
B) mutant swarm.
C) outbreak.
D) pandemic.

Question 5

People who have been vaccinated for the flu but still contract it are less likely to

A) suffer severe symptoms.
B) end up in the intensive care unit.
C) get the flu next flu season.
D) a and b
E) a, b, and c

Question 6

How many pieces of RNA does a flu virus have?

A) 1
B) 8
C) 13
D) 23

Question 7

In the future, an increase in emerging pathogens from animal sources is

A) an inevitable consequences of evolution.
B) likely to decrease as scientists find ways to combat viruses.
C) likely to increase as humans intrude farther into wild regions.
D) not a likely threat because scientists have eliminated viruses like SARS.

Question 8

Harmless bacteria from the environment can become pathogenic once they are inside a host because

A) bacteria can survive in many types of environments.
B) the host does not have antibodies to fight the bacteria.
C) the bacteria can evolve adaptations to survive in the host.
D) the host environment has nutrients the bacteria need to be pathogenic.

Question 9

The virulence of a pathogen is not fixed, meaning that

A) pathogens can't evolve to become more virulent.
B) pathogens can evolve to become more or less virulent.
C) all species of pathogens do not have the same virulence.
D) virulence can vary among species but not within a species.

Question 10

Most antibiotics in the United States are

A) used to treat human infections.
B) included in household cleaning products.
C) used to treat sick livestock.
D) given to healthy farm animals.

Question 11

What fraction of the world's population got sick with the flu in 1918?

A) 1/100
B) 1/10
C) 1/3
D) 1/2

Question 12

The phenomenon that can produce high frequencies of deleterious alleles in small, isolated populations is

A) antigenic shift.
B) the founder effect.
C) natural selection.
D) resistance.

Question 13

A group of antibiotic-resistant genes is known as a

A) bundle.
B) cassette.
C) conjugate.
D) lineage.

Question 14

The argument that susceptibility to diabetes and obesity rose as people adapted to different climates provides an alternative to which idea?

A) antagonistic pleiotropy
B) hygiene hypothesis
C) Old Friends hypothesis
D) thrifty genotype hypothesis

Question 15

The thrifty genotype hypothesis proposes

A) that alleles causing diseases such as diabetes were advantageous at some point in our evolutionary history.
B) that modern diets are often rich in nutrients that were more scarce over our evolutionary history.
C) that conditions experienced by a developing fetus can affect physiology throughout life.
D) a and b
E) a, b, and c

Question 16

Which of the following diseases does not generally follow Mendelian rules of inheritance?

A) breast cancer
B) cystic fibrosis
C) Huntington's
D) sickle-cell anemia

Question 17

The weakened viruses contained in live-virus vaccines can

A) trigger an immune response.
B) evolve into a new strain of virus.
C) be ineffective at providing immunity.
D) cause the same symptoms as the normal virus.

Question 18

Which of the following viruses is incorrectly paired with its animal source?

A) HIV-apes
B) influenza-birds
C) Lassa-rats
D) SARS-mice

Question 19

Individuals who inherit silent or defective alleles of tumor-suppressor genes

A) will inevitably develop cancer during their lifetime.
B) require fewer spontaneous somatic mutations to start tumor growth.
C) are less susceptible to environmental mutagens.
D) all of the above

Question 20

Two copies of the HbS allele cause sickle-cell anemia, but a single HbS allele helps protect individuals from malaria. This is an example of

A) antigenic shift.
B) heterozygote advantage.
C) reassortment.
D) natural selection.

Question 21

The figure below shows two regions (p17 and V3) of the HIV genome in the same patient. Which of the following conclusions can be drawn from the graph?

A) V3 has gone through more evolutionary change than p17.
B) p17 is less tolerant of mutations than V3.
C) Mutations in the V3 region are likely to have neutral or positive effects.
D) all of the above

Question 22

Which of the following processes help(s) to explain the high incidence of certain rare genetic diseases in the Amish?

A) bottlenecks
B) inbreeding
C) natural selection
D) a and b
E) a, b, and c

Question 23

Mutations that increase the risk of breast cancer in women are also associated with higher rates of childbirth. This is an example of

A) antagonistic pleiotropy.
B) antigenic shift.
C) balancing selection.
D) thrifty genotypes.

Question 24

The e4 allele is common in the world population (14.5% of people are carriers) despite being a risk factor for Alzheimer's disease. Which idea best explains this?

A) antagonistic pleiotropy
B) hygiene hypothesis
C) "Old Friends" hypothesis
D) thrifty genotype hypothesis

Question 25

What were Ron Fouchier and colleagues trying to find out with their serial passage experiment in ferrets?

A) how the global spread of bird flu could be prevented
B) the number of people that could die in a future bird flu outbreak
C) how bird flu evolved the capacity to establish itself in the human airway
D) the mutations that would give bird flu the capacity to spread from person to person

Question 26

In the following figure, what does the length of the branches show?

A) time
B) haplotype frequency
C) morphological change
D) genetic difference

Question 27

Which of the following is not a way that the human eye is maladaptive?

A) It has a blind spot.
B) It has camera-like vision.
C) The retina can easily detach.
D) The lens proteins cannot be repaired.

Question 28

Pathogens evolve rapidly because

A) they can detoxify drugs.
B) they reproduce rapidly.
C) their random mutation rates are high.
D) b and c
E) a, b, and c

Question 29

Viruses and bacteria can acquire additional genetic variation through

A) horizontal gene transfer.
B) recombination.
C) sexual reproduction.
D) single nucleotide polymorphisms.

Question 30

The flu virus can evade the human immune system with mutations that

A) reduce the virulence of the flu.
B) provide more efficient replication.
C) change the tip of the hemagglutinin stalk.
D) all of the above

Question 31

Storing more fat has been shown to be adaptive

A) a low abundance of pathogens.
B) an unpredictable food supply.
C) colder temperatures.
D) lots of predators.

Question 32

Which of the following is a way that researchers are trying to predict the next pandemic?

A) carrying out viral evolution experiments in the lab
B) cataloging the diversity of existing pathogens
C) using computers to model the emergence of new strains
D) increased monitoring of people who have frequent contact with animals
E) all of the above

Question 33

How can we slow the evolution of antibiotic resistance in bacteria?

A) Discover new, stronger antibiotics.
B) Reduce the use of antibiotics.
C) Increase doses of existing antibiotics.
D) There is nothing we can do.

Question 34

Understanding how selection affects virulence has led public health officials to use which of the following actions to reduce the transmission of pathogens?

A) providing clean drinking water
B) encouraging hand washing
C) vaccinating a large portion of the population
D) all of the above

Question 35

In a serial passage experiment, the evolution of bacterial virulence is no longer constrained by

A) antibodies.
B) replication.
C) selection.
D) transmission.

Question 36

Which of the following results would provide support for the thrifty genotype hypothesis?

A) Alleles involved in the development of diabetes show signatures of positive selection in the past.
B) Mice with diabetes reproduce less under conditions of persistent food stress.
C) Genome sequencing of 60,000-year-old human fossils reveals that alleles linked with diabetes were at a lower frequency in the past.
D) all of the above
E) none of the above

Question 37

Which of the following helps to explain why antibiotic resistance can evolve especially quickly?

A) Bacteria reproduce quickly.
B) Bacteria can acquire genes from other bacteria.
C) Antibiotics provide strong selection pressure.
D) all of the above

Question 38

Selection within pathogen hosts typically favors ________; selection across hosts favors ________.

A) more virulent strains; less virulent strains
B) less virulent strains; more virulent strains
C) less virulent strains; less virulent strains
D) more virulent strains; more virulent strains

Question 39

Which statement best describes antagonistic pleiotropy?

A) Certain diseases have low frequencies in young people, but the frequencies increase as people age.
B) There are many genes that work together to control aging and thus many opportunities for mutations.
C) Some diseases have low frequencies in geographic populations with high frequencies of certain mutations.
D) Mutations contributing to aging can increase in frequency if those same mutations promote fitness earlier in life.

Question 40

To create a drug that would stop infections of Pseudomonas aeruginosa in people with cystic fibrosis without encouraging the evolution of drug-resistant strains, researchers are trying to target the bacteria's ability to

A) move from host to host.
B) bind to iron in the host.
C) form colonies in the lungs of the host.
D) bind to surface proteins on the host cells.

Question 41

After studying the phylogeny of the Lassa virus, scientists discovered that viruses from different regions were not closely related to each other. This supports the hypothesis that

A) the virus was spreading from person to person.
B) the virus jumped from rats to people recently.
C) the virus was jumping repeatedly from rats to people.
D) there were no genetic patterns to the transmission of the virus.

Question 42

Sequencing genomes of the Lassa virus to test hypotheses about its spread is an example of the application of

A) evolutionary medicine.
B) medical biology.
C) genetics.
D) phylogenies.

Question 43

Mutations occur across the genome at random, but tumors form when a mutation occurs in genes that control

A) the production of antibodies.
B) the rate of cell division.
C) the regulation of hormones.
D) the storage of energy.

Question 44

Which of the following patterns suggests that cytomegalovirus has tracked the evolution of its primate hosts for millions of years?

A) The cytomegalovirus phylogeny mirrors the phylogeny of primates.
B) The cytomegalovirus phylogeny mirrors the phylogeny of other viruses.
C) The cytomegalovirus phylogeny has fewer branches than the phylogeny of primates.
D) The cytomegalovirus phylogeny is very different from the phylogeny of nonhuman primates.

Question 45

We take a number of measures to decrease the spread of viruses from one person to another (for example, vaccines). Over time, what effect might these efforts have on the evolution of virulence in pathogens?

Question 46

The relationship between the presence of malaria and high frequencies of the disease-causing HbS allele in Africa is an example of which type of selection?

A) balancing
B) directional
C) disruptive
D) sexual

Question 47

What is the name of the phenomenon that explains why a new flu vaccine must be created every year?

A) antigenic drift
B) antigenic shift
C) resistance
D) virulence

Question 48

There are many hypotheses about why obesity and diabetes are increasing in modern societies, many of them based on evolutionary mismatch. Describe three of these hypotheses.

Question 49

At present, what is the most common cause of death in developed countries?

A) infectious diseases
B) noncommunicable diseases
C) childhood diseases
D) zoonotic diseases

Question 50

Which of the following scenarios best illustrates antagonistic pleiotropy?

A) Individuals with the S allele for hemoglobin have increased immunity to malaria.
B) Certain alleles can make individuals more susceptible to drugs that destroy blood clots.
C) Genes that affect cardiovascular disease also affect reproductive traits early in life.
D) Some genetic disorders like color blindness are more common in isolated island populations.

Question 51

The line in the following graph shows that over time

A) mice become less susceptible to disease.
B) mice become more susceptible to disease.
C) bacteria evolve from low to high virulence.
D) bacteria evolve from high to low virulence.

Question 52

What does the flu virus use the protein hemagglutinin for?

A) to weaken the membrane of the host cell
B) to aid in copying the flu genome
C) to latch onto acids on the host cell
D) to recruit the host cell's genetic machinery

Question 53

Which of the following statements best describes the hypothesis for how the human SARS virus came into being?

A) Two different species of bats bit a Chinese farmer.
B) Different viral strains repeatedly jumped from infected bats to humans.
C) The virus tracked the evolution of humans over thousands of years.
D) Two strains of the virus in one bat mixed their genes through recombination.

Question 54

Increases in the average life span since the mid-20th century are driven by

A) declining childhood mortality.
B) increasing of the maximum life span.
C) increasing survival of people over 45.
D) all of the above

Question 55

Evolving very rapidly (hypermutation) would favor bacteria living in

A) less challenging environments.
B) unchanging environments.
C) novel, extreme environments.
D) any environment.

Question 56

What fraction of human proteins have evolved new amino acids under selection pressure from viruses?

A) 1/10
B) 1/3
C) 1/2
D) 2/3

Question 57

The frequency of Huntington's disease can increase in a population because

A) the disease only affects certain ethnic groups.
B) the disease has a dominant pattern of inheritance.
C) symptoms generally emerge after reproductive age.
D) the mutation that causes it protects individuals against other diseases.

Question 58

Considering the evolution of antibiotic resistance, why is it important that patients finish their full cycle of antibiotic treatment?

Question 59

Imagine that in the future we discover a set of genes that is largely responsible for causing aging in humans. Also, imagine that we can alter these genes in some way so that we live longer. Considering antagonistic pleiotropy, why might this be a concern?

Question 60

Octopus eyes differ from human eyes in that

A) octopuses have camera-vision eyes.
B) octopus eyes do not have blind spots.
C) the retinal blood vessels penetrate the eyeball.
D) b and c
E) a, b, and c

Question 61

When designing a live-virus vaccine (for example, the polio vaccine), how do scientists ensure that the virus will not cause human recipients to become ill with the virus?

Question 62

How could the movement of soldiers and unsanitary conditions during World War I have led to the evolution of a more virulent flu strain in 1918?

Question 63

How does the fact that horizontal gene transfer among bacteria is relatively common influence the rate at which antibiotic resistance evolves?

Question 64

You are studying a virus that infects mammals. You are specifically interested in whether the virus frequently jumps from one mammal species to another or whether different strains remain specific to certain hosts over evolutionary time. How could you use phylogenetic methods to test this?

Question 65

A drug called AZT was the first to be used against HIV. Although it initially worked, resistance developed quickly, and eventually the drug was no longer effective. Drug therapies used today, which often combine several different drugs that target different phases of the HIV life cycle into a cocktail, are much more effective over the long term than a single drug used in isolation. Please provide an evolutionary explanation for why newer therapies work better.

Question 66

Despite its complexity, the human eye still has its flaws. Why is the human eye a fitting example for how we can better understand the evolution of the human immune system?

Question 67

Explain, from an evolutionary perspective, why diseases such as smallpox and measles had such a devastating impact on populations indigenous to the New World.

Question 68

Describe how knowing the ancestry and genetic makeup of an individual could help doctors diagnose and treat them.

Question 69

Once cancer cells develop within the body, selection favors their proliferation even though this ultimately may lead to the death of the individual and the cancer cells. What explains this short-sighted evolution?

Question 70

Why is sickle-cell anemia more common in Africa than the United States?