Deck 13: Natural Selection and Adaptation

Question 1

Which statement regarding drug-resistant bacteria is false?

A) Antibiotic-resistant bacteria are more fit for an environment where antibiotics are used frequently.
B) The ability to resist antibiotics may cause bacteria to be less fit in other environments where antibiotics are not present.
C) Bacteria that are sensitive to antibiotics have a reproductive advantage in all environments.
D) Bacteria with alleles for antibiotic resistance can pass that trait on to their offspring.
E) The phenotype of a bacterium determines its fitness for an environment where antibiotics are present.

Answer 1

C

Question 2

Which statement expresses the only way to prevent the evolution of new antibiotic-resistant bacteria?

A) Stop giving antibiotics to livestock.
B) Develop new antibiotics.
C) Increase the rates of handwashing.
D) Stop using antibiotics entirely.
E) all of these

Answer 2

D

Question 3

Which factor may prevent most people from developing more than minor skin blemishes when they have a staph infection?

A) Their immune systems are preventing the infection from spreading.
B) Helpful bacteria on their skin keep staph in check.
C) Their skin is a physical barrier that keeps out the bacteria.
D) They are practicing good hygiene,including frequent hand washing.
E) all of these

Answer 3

E

Question 4

A bacterial cell with which modification might be resistant to antibiotics such as methicillin?

A) the ability to contaminate surfaces in areas such as locker rooms
B) the ability to produce toxins that kill the human host
C) the ability to spread through contact between people
D) the ability to produce an enzyme that breaks down the antibiotic
E) the ability to cause skin infections such as pimples

Question 5

Antibiotic-resistant strains of bacteria tend to first be found in hospitals.Which factor explains why this is the case?

A) A hospital has more bacteria than would be found in other places.
B) Sick people are more likely to provide an environment where resistant strains are favored.
C) Bacteria cannot survive as successfully in areas outside of hospitals.
D) Antibiotics are more likely to be present in hospitals,thus selecting for resistant strains.
E) Bacteria can reproduce more easily in a hospital environment than in other places.

Question 6

Which statement about evolution by natural selection is false?

A) Natural selection is a random change in allele frequencies over generations.
B) Evolution by natural selection affects populations of organisms,not individual organisms.
C) Natural selection favors those traits that confer higher fitness in the environment.
D) Natural selection allows organisms with higher fitness to reproduce more successfully.
E) Evolution by natural selection occurs more rapidly in organisms with high reproductive rates.

Question 7

What is the evolutionary process called that causes antibiotic-resistant bacteria to increase and antibiotic-sensitive bacteria to decrease in an environment where antibiotics are present?

A) bacterial selection
B) antibiotic selection
C) natural selection
D) environmental selection
E) evolutionary selection

Question 8

All of these statements are true regarding S.aureus EXCEPT:

A) it can be transmitted from person to person through used bar soap.
B) nearly 1% of the U.S.population is colonized with S.aureus.
C) it can cause pimples,boils,and wound infections in otherwise healthy individuals.
D) it can secrete toxic substances that can interfere with cellular functions.
E) all of these

Question 9

An organism's fitness depends on its _____.

A) ability to survive and reproduce
B) population
C) ability to mutate
D) physical size
E) ability to swap genetic material with other organisms

Question 10

A bacterial cell that is resistant to a particular antibiotic may spend a large amount of energy producing the modified proteins that are needed for resistance.In such a case,what would be the effect on this cell's fitness if no antibiotic was present?

A) Its fitness would be the same as other strains that lack resistance because no antibiotics affect any of them.
B) Its fitness would be higher than other strains that lack resistance because it is prepared for a future change in the environment.
C) Its fitness would be lower than other strains that lack resistance because it is spending energy that the resistant strains can use for other purposes,such as reproduction.
D) Its fitness would be higher than other strains that lack resistance because it has more available energy to use.
E) Its fitness would be the same as other strains that lack resistance because bacteria have access to so much energy in the environment that it is not an issue in their fitness.

Question 11

The development and spread of a new gene for antibiotic-resistance in a population of bacteria that are exposed to that antibiotic would mean that trait is a(n)_____.

A) disruptive trait
B) consistent phenotype
C) swapped gene
D) stabilizing trait
E) adaptation

Question 12

Which factor is not going to affect how natural selection acts on a given group of organisms?

A) survival rate of individuals
B) reproductive success of individuals
C) which phenotypes are present
D) none of these
E) all of these

Question 13

Which changes in a bacterial cell might reduce the effectiveness of beta-lactam antibiotics?

A) the presence of modified DNA that does not bind to the antibiotic
B) the presence of enzymes that are able to break down the antibiotic
C) the presence of cell membranes to which the antibiotic cannot bind
D) the presence of a thinner cell wall
E) all of these

Question 14

If you examine a natural population of bacteria,it is common to find some antibiotic-sensitive and some antibiotic-resistant strains,even if the population has never been exposed to any antibiotic.Which explanation could account for this situation?

A) The resistant strain developed as a mutation and had no negative effect on fitness.
B) Selection favored the resistant strain and maintained it in the population so that it would be prepared for future antibiotic exposure.
C) The resistant strain had greater fitness compared to sensitive strains when the antibiotic was absent.
D) none of these
E) all of these

Question 15

Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"?

A) because bacteria do not apply a selection pressure on human populations
B) because we do not have the mutations that would improve our immune systems
C) because the rate of human evolution is much slower than bacterial evolution
D) none of these
E) all of these

Question 16

Which of these is NOT a pattern of natural selection?

A) diversifying selection
B) stabilizing selection
C) directional selection
D) all of these
E) none of these

Question 17

In strains of bacteria that are not resistant to beta-lactams,which part(s)of the bacterial cells are disrupted by the antibiotic?

A) the cell membranes
B) the nuclear membranes
C) the cell walls
D) the cytoplasm
E) the DNA

Question 18

Which process has been shown to contribute to the evolution of antibiotic resistance in S.aureus?

A) gene swapping with other bacterial strains
B) overuse of antiviral medications
C) genetic mutations during asexual reproduction
D) none of these
E) all of these

Question 19

An individual who carries staph but isn't sick is referred to as _____.

A) infected
B) resistant
C) colonized
D) evolving
E) none of these

Question 20

Why is the evolution of antibiotic resistance in bacteria happening so quickly?

A) because of overuse of antibiotics in humans
B) because bacteria can reproduce so quickly
C) because any use of antibiotics will select for resistant bacteria
D) because of overuse of antibiotics in livestock
E) all of these

Question 21

Which of the following is TRUE of ß-lactams?

A) They are only prescribed for the most drug-resistant forms of Staphylococcus aureus.
B) They cause a cell to burst open from water pressure.
C) Vancomycin is one of the most effective ß-lactams.
D) They must be administered with caution because they can damage human tissues with prolonged use.
E) They are one of the few classes of drugs that are effective against both bacteria and viruses.

Question 22

ß-lactam antibiotics act by interfering with

A) bacterial cell wall synthesis.
B) the uptake of bacteria.
C) bacterial cell division.
D) bacterial chromosome replication.
E) the ability of the bacteria to avoid the host's immune system.

Question 23

MRSA should routinely be treated with

A) penicillin.
B) a ß-lactam antibiotic.
C) cephalosporin.
D) vancomycin.
E) cephalexin.

Question 24

MRSA is resistant to

A) penicillin.
B) ß-lactam antibiotics.
C) cephalosporin.
D) methicillin.
E) All of the above.

Question 25

Staphylococcus aureus is a type of

A) pathogenic spore.
B) virus.
C) bacteria.
D) fungi.
E) pathogenic fungi.

Question 26

What percentage of people carry ANY form of Staphylococcus aureus on their skin or in their noses?

A) 1%-5%
B) 5%-10%
C) 10%-25%
D) 30%-40%
E) 50%-60%

Question 27

If the cell wall of Staphylococcus aureus fails to form properly,water will enter the cell

A) by the process of osmosis.
B) by the process of imbibition.
C) by active transport.
D) to destroy the bacterial DNA.
E) to help maintain the cell's turgor pressure.

Question 28

A student who shares a dorm suite and bathroom with seven other students has contracted a skin infection caused by MRSA.Based on what you know about MRSA and about the student,where would you look first for the source of the bacteria?

A) contaminated equipment at the gym
B) contaminated shared food
C) contaminated used soap and towels
D) a suitemate with an upper respiratory infection who is sneezing and coughing
E) shared hypodermic needles

Question 29

If the cell wall of Staphylococcus aureus fails to form properly,water will

A) create a secondary wall around the cell.
B) drain out of the cell rapidly,causing it to dehydrate.
C) drown the bacteria.
D) rush into the cell,causing it to explode.
E) create a bridge of hydrogen bonds to repair the wall.

Question 30

Why doesn't a ß-lactam antibiotic prevent the growth of new host (human)cells?

A) The host cells are slowed down by the antibiotic but still grow faster than the bacteria.
B) The host cells are protected by a thick layer of cell-wall peptidoglycan.
C) Osmosis only occurs in bacterial cells,never in human or animal cells.
D) The antibiotic only harms bacterial cell walls;the host cells do not have cell walls.
E) Antibiotics slow host cell growth,but after the bacteria are dead and the antibiotics are removed,the host cells can grow again.

Question 31

Which of the following people is/are especially vulnerable to illness caused by drug-resistant bacteria?

A) a 3-month-old baby
B) a 90-year-old man
C) an athlete with several cuts on his arms and legs
D) a person with pneumonia
E) All of the above people are especially vulnerable.

Question 32

Staphylococcus aureus can cause

A) boils.
B) sores.
C) pimples.
D) death.
E) All of the above.

Question 33

All of the following are true of MRSA,EXCEPT

A) MRSA used to be confined to hospitals but now is showing up in healthy individuals outside hospitals.
B) some strains may be resistant to multiple antibiotics.
C) anyone who comes into contact with MRSA will become sick.
D) MRSA can secrete toxins.
E) it can be acquired through inhalation.

Question 34

MRSA is caused by

A) Streptococcus aureus.
B) a drug-resistant form of S.aureus.
C) S.aureus USA300.
D) a drug-resistant form of a virus.
E) a drug-resistant form of Methicillin aureus.

Question 35

Which of the following people are at the lowest risk of acquiring MRSA?

A) a computer consultant who works from home
B) someone who works as a guard at a local prison
C) a rugby player on a successful team
D) a worker in a local daycare
E) a janitor at a major city hospital

Question 36

What percentage of people carry antibiotic-resistant strains of Staphylococcus aureus on their skin or in their noses?

A) about 2%
B) about 5%
C) about 10%
D) about 12%
E) about 30%

Question 37

MRSA can be contracted by

A) skin-to-skin contact.
B) contact with open wounds.
C) contact with contaminated surfaces.
D) contact with contaminated soap and towels.
E) All of the above.

Question 38

Antibiotics should only be prescribed for

A) fungal infections.
B) viral infections.
C) bacterial and fungal infections.
D) bacterial infections.
E) a flulike illness.

Question 39

Which of the following is NOT a possible way of transmitting a Staphylococcus aureus infection?

A) sharing towels
B) skin-to-skin contact
C) contact sports
D) inhalation
E) All of the above ARE possible methods.

Question 40

Which of the following is TRUE of ß-lactams?

A) They prevent transcription.
B) They prevent a cell from acquiring nutrients.
C) They prevent a cell from reproducing.
D) They prevent a cell from making ATP.
E) They cause a cell to burst open.

Question 41

A bacterial strain divides once every 30 minutes.After 90 minutes,a single bacterium can form a total of ___ bacteria.

A) 3
B) 6
C) 8
D) 16
E) This answer cannot be calculated from the information given.

Question 42

Binary fission is a form of

A) nuclear division.
B) aerobic reproduction.
C) anaerobic reproduction.
D) asexual reproduction.
E) sexual reproduction.

Question 43

The severity of a bacterial infection is related to

A) the health of the patient.
B) whether the bacteria produce toxins.
C) whether the bacteria have a way to avoid the immune system.
D) which part of the body is infected.
E) All of the above.

Question 44

If a bacterium susceptible to ß-lactam antibiotics were placed in an isotonic solution and exposed to antibiotics,

A) its cell wall would rupture and burst due to the influx of water caused by osmosis.
B) its cell membrane would rupture and burst due to the influx of water caused by osmosis,but its cell wall would remain intact.
C) osmosis would drive water out of the cell,causing it to shrivel and die due to lack of internal fluids.
D) it would remain intact because osmosis would cause no change in water flow into or out of the cell.
E) it would remain intact because the cell wall is strong enough to withstand the pressure caused when osmosis draws water into the cell.

Question 45

Which of the following is TRUE of bacterial reproduction?

A) The daughter cells are identical to the parent cell.
B) One cell divides to produce four cells.
C) Reproduction is sexual and thus allows for genetic diversity in the new cells.
D) It takes 24 hours for a bacterial population to double in size.
E) Bacterial reproduction is called binary fusion.

Question 46

Bacteria can divide as often as once every

A) 3 hours.
B) minute.
C) hour.
D) day.
E) 20 minutes.

Question 47

Bacteria usually reproduce by

A) meiosis.
B) sexual reproduction.
C) binary fission.
D) binary fusion.
E) transformation.

Question 48

What is responsible for genetic variation in bacteria?

A) mutations in the genome during binary fission
B) gene influx from a different bacterial strain
C) DNA influx from the environment
D) gene transfer from the same bacterial species
E) All of the above.

Question 49

Overprescription of antibiotics and their improper use is a cause of

A) a decrease in drug-resistant species.
B) elimination of drug-resistant species.
C) a rise in drug-resistant bacterial populations.
D) keeping the level of MRSA infections stable.
E) decreasing MRSA levels in hospitals.

Question 50

Bacterial cell division is known as

A) friction.
B) cytofission.
C) fusion.
D) fission.
E) nuclear fission.

Question 51

Each bacteria cell typically splits into ______ new cells.

A) 2
B) 3
C) 4
D) 8
E) 20

Question 52

After bacterial asexual reproduction,the daughter cells produced

A) are identical to each other.
B) have half the chromosome number.
C) are genetically different.
D) have double the DNA content.
E) exchange genes by transformation.

Question 53

What is the drug of choice when a patient has a severe drug-resistant infection?

A) penicillin
B) methicillin
C) vancomycin
D) cephalexin
E) amoxicillin

Question 54

A population is described as

A) all the members of the same species located on a continent.
B) the species that live in a geographic area.
C) all the species occupying a specific locale.
D) all the members of the same species living in the same area.
E) the species richness.

Question 55

Your friend has contracted a bacterial infection.Which of the following hypothetical drugs would you suggest as the best way to prevent an antibiotic-resistant allele from arising and spreading throughout the bacterial population in her body?

A) a drug that prevents mutations but allows gene swapping
B) a drug that doesn't prevent mutations but does prevent gene swapping with individuals of its own species
C) a drug that doesn't prevent mutations but does prevent gene swapping with individuals of other species
D) a drug that doesn't prevent mutations but prevents gene swapping with any individual of any species
E) a drug that prevents both mutations and gene swapping

Question 56

Which of the following hypothetical antibiotics would treat bacterial infections by interfering with bacterial reproduction?

A) one that changes one of the proteins on the cell membrane
B) one that interferes with cell membrane synthesis
C) one that enhances DNA replication
D) one that strengthens bacterial cell walls
E) one that enhances protein synthesis

Question 57

All the individuals of a species living in a specific area compose a

A) colony.
B) species.
C) community.
D) population.
E) clade.

Question 58

Bacteria reproduce by a process called

A) cellular bifurcation.
B) cleavage.
C) bipolarization.
D) binary fission.
E) divergent fusion.

Question 59

Drug-resistant populations of bacterial stains are a result of

A) fast bacterial doubling time outpacing typical drug doses.
B) drugs or other selective environmental pressures.
C) binary fission.
D) manipulations in the lab to create new strains for research.
E) transmission from an infected person.

Question 60

If bacterial cells can divide every 20 minutes,how many bacteria will be present after 2 hours if the starting population is 100 cells?

A) 700
B) 1200
C) 1300
D) 3200
E) 6400

Question 61

How would the resistance level of an antibiotic-sensitive variant in culture medium containing a minimal amount of antibiotics change over time?

A) resistance will remain low
B) resistance will remain medium
C) resistance will remain high
D) resistance will change from high,to medium,and finally low
E) resistance will change from low,to medium,and finally high

Question 62

A bacterial strain will most likely become antibiotic resistant when it is grown in

A) high heat.
B) extreme cold.
C) the presence of an acidic environment.
D) the presence of MRSA.
E) a laboratory that researches viruses.

Question 63

What would the outcome be if an antibiotic-sensitive homogeneous (no variation)strain of S.aureus was grown in the presence of antibiotics?

A) cell growth that begins slowly but proceeds rapidly
B) rapid mutation and growth
C) no cell growth
D) eventual rise of antibiotic-resistant cells
E) rapid growth then sudden death

Question 64

Which is necessary for natural selection to proceed?

A) variation within a population
B) a mechanism of inheritance
C) acquisition of adaptations
D) generations reproducing over time
E) All of the above.

Question 65

Which of the following is more fit?

A) a 5000-year-old bristlecone pine tree that produced 1 offspring every 100 years
B) a 5000-year-old bristlecone pine tree that produced 3 offspring every 100 years
C) a 3000-year-old bristlecone pine tree that produced 100 offspring every 100 years
D) a 2000-year-old bristlecone pine tree that produced 100 offspring every 10 years
E) a 500-year-old bristlecone pine tree that produced 100 offspring every year

Question 66

Natural selection causes

A) changes in an individual's genes.
B) changes in allele frequencies within a population.
C) a decrease in reproductive fitness in a population.
D) the inheritance of acquired characteristics.
E) changes in the mechanism of inheritance.

Question 67

Which has made the biggest impact on future generations?

A) a 5000-year-old bristlecone pine tree that produced 1 offspring every 100 years
B) a 5000-year-old bristlecone pine tree that produced 3 offspring every 100 years
C) a 3000-year-old bristlecone pine tree that produced 100 offspring every 100 years
D) a 2000-year-old bristlecone pine tree that produced 100 offspring every 10 years
E) a 500-year-old bristlecone pine tree that produced 100 offspring every year

Question 68

Five different strains of bacterial cultures were grown overnight in a medium containing antibiotics.Of the resulting population densities listed below,which was the most fit?

A) 5 × 10⁵ cells/ml
B) 6 × 10⁶ cells/ml
C) 7.5 × 10⁷ cells/ml
D) 0.075 × 10⁸ cells/ml
E) 5 × 10⁷ cells/ml

Question 69

All of the following are true of evolution,EXCEPT

A) evolution leads to individuals with higher fitness than their predecessors.
B) individuals adapt their genes to improve survival.
C) the environment plays a large role in the process of evolution.
D) individuals with the most adaptive phenotypes have the most offspring.
E) evolution works through natural selection.

Question 70

An organism's ability to survive and reproduce is called the organism's

A) natural selectivity.
B) advantage.
C) phenotype.
D) genotype.
E) fitness.

Question 71

Natural selection that favors survival of extreme phenotypes of a population is called

A) artificial selection.
B) stabilizing selection.
C) diversifying selection.
D) directional selection.
E) extremophenotypic selection.

Question 72

Human birth weight is an example of

A) directional selection.
B) diversifying selection.
C) guided selection.
D) stabilizing selection.
E) uniform selection.

Question 73

All of the following are true of natural selection,EXCEPT

A) it works best in genetically uniform populations.
B) it results in populations better suited to their environment than their predecessors.
C) it is the process by which evolution occurs.
D) it results in some individuals surviving better and reproducing more than others.
E) it results in a change in allele frequencies over time.

Question 74

MRSA in humans is an example of

A) directional selection.
B) diversifying selection.
C) guided selection.
D) stabilizing selection.
E) uniform selection.

Question 75

A number of mosquito populations today are resistant to specific insecticides,even though those insecticides were highly effective when they were first introduced.Biologists believe that insecticide resistance evolved in mosquitoes because

A) individual mosquitoes built up an immunity to an insecticide after being exposed to it.
B) mosquitoes needed to develop insecticide resistance to survive after the insecticide was used.
C) a few mosquitoes were probably resistant to the insecticide before it was ever used.These survived and passed that trait on to their offspring.
D) the presence of the insecticide caused some mosquitoes to develop resistance;they survived and passed the trait to their offspring.
E) current mosquito populations are phenotypically variable and exhibit different levels of fitness in different environments.

Question 76

Which bacterial phenotype would have the highest fitness if it were cultured in a medium containing antibiotics?

A) a slightly antibiotic-resistant variant
B) a moderately antibiotic-resistant variant
C) a highly antibiotic-resistant variant
D) an antibiotic-sensitive variant
E) all phenotypes have equal fitness

Question 77

The African finch Pyrenestes is an example of

A) directional selection.
B) diversifying selection.
C) guided selection.
D) stabilizing selection.
E) uniform selection.

Question 78

Drug resistance may take which of the following forms?

A) Bacteria may produce ß-lactamases.
B) Bacteria may produce proteins that can disable antibiotics.
C) Bacteria may produce proteins with altered shapes that antibiotics can no longer bind to.
D) All of the above.
E) None of the above.

Question 79

Which of the following factors will NOT influence the rate at which drug resistance can evolve in a population of bacteria?

A) mutation rate
B) the frequency of gene swapping with members of the same species
C) the frequency of gene swapping with members of different species
D) the frequency of reproduction
E) the age of the host

Question 80

A highly resistant antibiotic strain of S.aureus would reproduce best in

A) the presence of antibiotic.
B) the absence of antibiotic.
C) the presence or absence of antibiotic.
D) a moderate concentration of antibiotic.
E) a fluctuating concentration of antibiotic