Ch. 13 Quiz

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

A.

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

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

Which statement regarding drug-resistant bacteria is false?

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

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 lower than other strains that lack resistance because it is spending energy that the resistant strains can use for other purposes, such as reproduction. Its fitness would be higher than other strains that lack resistance because it has more available energy to use. Its fitness would be the same as other strains that lack resistance because no antibiotics affect any of them. Its fitness would be higher than other strains that lack resistance because it is prepared for a future change in the environment. 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.

Which statement about evolution by natural selection is false?

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

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

A. Stop using antibiotics entirely. all of these Develop new antibiotics. Increase the rates of handwashing. Stop giving antibiotics to livestock.

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. Selection favored the resistant strain and maintained it in the population so that it would be prepared for future antibiotic exposure. all of these The resistant strain had greater fitness compared to sensitive strains when the antibiotic was absent. none of these

An organism's fitness depends on its _____.

A. ability to survive and reproduce physical size ability to mutate population ability to swap genetic material with other organisms

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. adaptation swapped gene stabilizing trait disruptive trait consistent phenotype

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

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

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

A. all of these because of overuse of antibiotics in livestock because any use of antibiotics will select for resistant bacteria because of overuse of antibiotics in humans because bacteria can reproduce so quickly

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

A. all of these none of these which phenotypes are present reproductive success of individuals survival rate of individuals

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

A. all of these overuse of antiviral medications none of these gene swapping with other bacterial strains genetic mutations during asexual reproduction

Which of these is NOT a pattern of natural selection?

A. all of these stabilizing selection diversifying selection directional selection none of these

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

A. colonized resistant infected none of these evolving

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. natural selection evolutionary selection antibiotic selection environmental selection bacterial selection

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

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

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

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

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 walls the DNA the cytoplasm the cell membranes the nuclear membranes

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

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