The past decade has seen a statistically significant uptick in reports of the bacterial strains known as “super-bugs,” so called not because of enhanced virulence, but because of their resistance to many antimicrobial agents. In particular, researchers have become alarmed about NDM-1 (New Delhi metallo-beta-lactamase), which is not a single bacterial species, but a transmittable genetic element encoding multiple resistance genes. A resistance “cocktail” such as NDM-1 could bestow immunity to a bevy of preexisting drugs simultaneously, rendering the bacterium nearly impregnable. However, in spite of the well-documented dangers posed by antibiotic-resistant bacteria, many scientists argue that the human race has more to fear from viruses. Whereas bacteria reproduce asexually through binary fission, viruses lack the necessary structures for reproduction, and so are known as “intracellular obligate parasites.” Virus particles called virions must marshal the host cell’s ribosomes, enzymes, and other cellular machinery in order to propagate. Once various viral components have been built, they bind together randomly in the cellular cytoplasm. The newly finished copies of the virus break through the cellular membrane, destroying the cell in the process. Because of this, viral infections cannot be treated ex post facto in the same way that bacterial infections can, since antivirals designed to kill the virus could do critical damage to the host cell itself. In fact, viruses can infect bacteria (themselves complete cells), but not the other way around. For many viruses, such as that responsible for the common cold sore, remission rather than cure is the goal of currently available treatment. While the insidious spread of drug-resistant bacteria fueled by overuse of antibiotics in agriculture is nothing to be sneezed at, bacteria lack the potential for cataclysm that viruses have. The prominent virologist Nathan Wolfe considers human immunodeficiency virus (HIV), which has resulted in the deaths of more than thirty million people and infected twice that 25 number, “the biggest near-miss of our lifetime.” Despite being the most lethal pandemic in history, HIV could have caused far worse effects. It is only fortunate happenstance that this virus cannot be transmitted through respiratory droplets, as can the viruses that cause modern strains of swine flu (H1N1), avian flu (H5N1), and SARS.
The main purpose of the passage can be expressed most accurately by which of the following? (A) To contrast the manner by which bacteria and viruses infect the human body and cause cellular damage
(B) To explain the operations by which viruses use cell machinery to propagate
(C) To argue for additional resources to combat drug-resistant bacteria and easily transmissible pathogenic viruses
(D) To highlight the good fortune experienced by the human race, in that the HIV pandemic has not been more lethal
(E) To compare the relative dangers of two biological threats and judge one of them to be far more important
The first paragraph introduces bacterial “super-bugs” with some alarm. The second paragraph increases the alarm, noting that “many scientists argue that the human race has more to fear from viruses.” This paragraph describes how viruses hijack the cell in order to illustrate how tough viruses are to treat. The last paragraph continues the comparison and puts a stake in the ground: “bacteria lack the potential for cataclysm that viruses have.” The point is further illustrated by the “near-miss” of the HIV pandemic. As for choice (A), it is unknown how bacteria infect the body. Regarding (B), the hijacking process is certainly described, but to make a larger point: why it’s hard to eradicate viruses in comparison with bacteria. As for (C), after reading this passage, you may want to call up the CDC and donate money, but the passage itself only raises a warning, if even that— it is not a call to action. Regarding choice (D), the last paragraph does highlight the human race’s good fortune, but this is not the larger point of the whole passage. Choice (E) is correct— the passage compares the two threats (bacteria and viruses) and judges viruses to be far more important (after all, viruses have the “potential for cataclysm”).
Q2.
According to the passage, infections by bacteria (A) result from asexual reproduction through binary fission
(B) can be treated ex post facto
(C) can be rendered vulnerable by a resistance cocktail such as NDM-1
(D) are rarely cured by currently available treatments, but rather only put into remission
(E) mirror those by viruses, in that they can both do critical damage to the host cell
Focus on the keywords “infections by bacteria” (which can be rearranged to “bacterial infections”). What does the text say about bacterial infections? The second paragraph gives a direct clue: “viral infections cannot be treated ex post facto in the same way that bacterial infections can.” In other words, bacterial infections can be treated “ex post facto” (which means “after the fact”). Choice (B) matches this idea. Regarding (A), the second paragraph states that bacteria themselves “reproduce asexually through binary fission,” but that isn’t necessarily true about infections by bacteria. Regarding (C), the first paragraph notes that resistance “cocktails” such as NDM-1 actually make bacteria “nearly impregnable.” As a result, an infection by bacteria that have this cocktail would be less vulnerable, not more vulnerable. Choices (D) and (E) are true about viral infections, but not bacterial infections.
Q3.
According to the passage, intracellular obligate parasites (A) are unable to propagate themselves on their own
(B) assemble their components randomly out of virions
(C) reproduce themselves through sexual combination with host cells
(D) have become resistant to antibiotics through the overuse of these drugs
(E) construct necessary reproductive structures out of destroyed host cells
This Specific Detail question asks what is true about “intracellular obligate parasites” (or IOPs, to give them a temporary abbreviation). The second paragraph states: “Whereas bacteria reproduce asexually through binary fission, viruses lack the necessary structures for reproduction, and so are known as ‘intracellular obligate parasites.’” The word “so” toward the end indicates that viruses are called IOPs because they “lack the necessary structures for reproduction.” Choice (A) captures this idea.
26 May 2016, 02:15
73% (02:30) correct
