Chapter 14 Study Questions
In strains of bacteria that are not resistant to beta-lactams, which of the following parts of the bacterial cells are disrupted by the antibiotic?
the cell walls
Which of the following changes in a bacterial cell might reduce the effectiveness of beta-lactam antibiotics?
the presence of enzymes that are able to break down the antibiotic
Which of the following statements about evolution by natural selection is FALSE
. Natural selection is a random change in allele frequencies over generations.
Antibiotic-resistant strains of bacteria tend to first be found in hospitals. Which of the following factors explains why this is the case?
Antibiotics are more likely to be present in hospitals, thus selecting for resistant strains.
Which of the following statements regarding drug-resistant bacteria is FALSE
Bacteria that are sensitive to antibiotics have a reproductive advantage in all environments.
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?
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.
Which of the following processes have been shown to contribute to the evolution of antibiotic resistance in S. aureus?
gene swapping with other bacterial strains and genetic mutations during S. aureus reproduction
All of the following are TRUE regarding S. aureus EXCEPT
Nearly 1% of the U.S. population is colonized with S. aureus.
Which of the following is the only way to prevent the evolution of new antibiotic-resistant bacteria?
Stop using antibiotics entirely.
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 of the following explanations could account for this situation?
The resistant strain developed as a mutation and had no negative effect on fitness.
Which of the following factors may prevent most people from developing more than minor skin blemishes when they suffer a staph infection?
Their immune systems are preventing the infection from spreading, Helpful bacteria on their skin keep staph in check, and Their skin is a physical barrier that keeps out the bacteria.
An organism's fitness depends on its
ability to survive and reproduce
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(an
adaptation
Why is the evolution of antibiotic resistance in bacteria happening so quickly?
because of overuse of antibiotics in humans, because bacteria can reproduce so quickly, because any use of antibiotics will select for resistant bacteria, and because of overuse of antibiotics in livestock
Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"?
because we may not have the mutations that would improve our immune systems and because the rate of human evolution is much slower than bacterial evolution
An individual who carries staph but isn't sick is referred to as
colonized
. Which of the following are patterns of natural selection?
diversifying selection b. stabilizing selection c. directional selection
What is the evolutionary process that causes antibiotic-resistant bacteria to increase and antibiotic-sensitive bacteria to decrease in an environment where antibiotics are present
natural selection
Which of the following factors is not going to affect how natural selection acts on a given group of organisms?
survival rate of individuals, reproductive success of individuals, which phenotypes are present
A bacterial cell with which of the following modifications might be resistant to antibiotics such as methicillin?
the ability to produce an enzyme that breaks down the antibiotic