Problem 1. Which of the following processes have been shown to contribute to the
ID: 165524 • Letter: P
Question
Problem 1. Which of the following processes have been shown to contribute to the evolution of antibiotic resistance in S. aureus?
a. gene swapping with other bacterial strains
b. excessive use of alcohol-based hand sanitizers
c. genetic mutations during S. aureus reproduction
d. Both a and c are correct.
e. All of the above can cause evolution of antibiotic resistance.
Problem 2. 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.
Problem 3. A bacterial cell with which of the following modifications 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
Problem 4. Antibiotic-resistant strains of bacteria tend to first be found in hospitals. Which of the following factors explains why this is the case?
a. A hospital has more bacteria than you would find 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.
Problem 5. 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
Problem 6. 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?
a. bacterial selection
b. antibiotic selection
c. natural selection
d. environmental selection
e. evolutionary selection
Problem 7. Which of the following statements 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.
Problem 8. 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 may not have the mutations that would improve our immune systems
c. because the rate of human evolution is much slower than bacterial evolution
d. Both b and c are correct.
e. All of the above are correct.
Problem 9. 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.
b. Selection favored the resistant strain and maintained it in the population so that it would be prepared for future antibiotic exposure.
c. The antibiotic-sensitive strain had greater fitness compared to resistant strains when the antibiotic was absent.
d. The resistant strain had greater fitness compared to sensitive strains when the antibiotic was absent.
e. all of the above
Problem 10. An individual who carries staph but isn't sick is referred to as _______.
a. infected
b. resistant
c. colonized
d. evolving
e. none of the above
Explanation / Answer
Problem 1.
Answer is e. Gene swapping with other microbal strain can cause antibiotic resistance in S. aureus. This is a type of lateral gene transfer in microbes. These days, alcohol-based hand sanitizers are in vogue. Excessive use of such products causes 'selection' of only potentially hazardous 'pre-adepted' strains. Genetic mutations in the course of reproduction in microbes in presence of antibiotics. These abobementioned all processes are responsible for antibiotic resistance.
Probelm 2.
The antibiotic resistance in microbes is happening quickly because overuse of antibiotics in humans and animals. The intake is more than what is recommended or tolerable. This is further aggravated by the short generation times of the microbes (such as about 20 minutes for E. coli). Exposing microbes to any antibiotic will select the resistance microbes. This can be further explained by the famous experiment done by Lederberg and Lederberg.
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