Chapter 14 Quiz
Which of the following statements about evolution by natural selection is FALSE?
a. Natural selection is a random change in allele frequencies over generations.
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?
a. 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?
a. Their immune systems are preventing the infection from spreading. c. Their skin is a physical barrier that keeps out the bacteria.
An individual who carries staph but isn't sick is referred to as _______.
a. ability to survive and reproduce
Which of the following processes have been shown to contribute to the evolution of antibiotic resistance in S. aureus?
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 the above are correct.]
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 the above are correct.]
Which of the following is not a pattern of natural selection?
a. diversifying selection b. stabilizing selection c. directional selection [d. All of the above are patterns of natural selection.]
An organism's fitness depends on its __________.
a. gene swapping with other bacterial strains c. genetic mutations during S. aureus reproduction
Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"?
b. Nearly 1% of the U.S. population is colonized with S. aureus.
Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"?
b. because we may not have the mutations that would improve our immune systems c. because the rate of human evolution is much slower than bacterial evolution
Which of the following changes in a bacterial cell might reduce the effectiveness of beta-lactam antibiotics?
b. the presence of enzymes that are able to break down the antibiotic
Why is the evolution of antibiotic resistance in bacteria happening so quickly?
c. 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?
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.
An individual who carries staph but isn't sick is referred to as _______.
c. colonized
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 called?
c. natural selection
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?
c. the cell walls
Antibiotic-resistant strains of bacteria tend to first be found in hospitals. Which of the following factors explains why this is the case?
d. Antibiotics are more likely to be present in hospitals, thus selecting for resistant strains.
Which of the following is the only way to prevent the evolution of new antibiotic-resistant bacteria?
d. Stop using antibiotics entirely.
A bacterial cell with which of the following modifications might be resistant to antibiotics such as methicillin?
d. the ability to produce an enzyme that breaks down the antibiotic
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) _______.
e. adaptation