Questions 16 to 17 refer to the passage below. For each question, select one answer
choice, unless the instructions state otherwise.The growth of aquaculture, or fish farming, may affect the levels of
certain contaminants in consumable fish and shellfish. Dense colonies
can increase stress and disease transmission among fish, in some cases
requiring the administration of antibiotics. Studies have also found
higher levels of certain contaminants in farmed fish than in their wild
counterparts, possibly due to differences in diet. For example, several
studies have found higher concentrations of PCBs, organochlorine
pesticides, and polybrominated diphenyl ethers (PBDEs) in farmed
salmon.
Overharvesting also can affect the condition of fish and shellfish—
not only the species being harvested, but also the species that prey on
them—by disrupting the food web. Because of depleted food sources,
predators can become more susceptible to disease (such as infection of
rockfish by mycobacterial lesions). These infections are often confined
to internal organs and may not be apparent to anglers, although in
some cases they are associated with external sores as well. Some types
of mycobacteria can also infect humans who handle diseased fish if the
infection comes into contact with an open wound. The slow-developing
infections are usually not severe in humans, but in some cases they can
cause major health problems, especially in people with compromised
immune systems.- Based on the information in the passage, which of the following can be
concluded? (Indicate all that apply.)
A It has consequences for species other than the ones being fished.
B Anglers have no way of identifying when a fish is infected.
C Stress has an impact on a fish’s immune system. - The author most likely mentions “PCBs, organochlorine pesticides, and
polybrominated diphenyl ethers (PBDEs)” in order to
A explain how differences in the diets of wild fish and farmed fish have
arisen
B support a claim about the relatively high levels of contaminants in
farmed fish
C illustrate the consequences of the diet of a typical farmed fish
D provide examples of measures to counteract the consequences of fish
farming
E explain the use of antibiotics on farmed fish
5101520534 PART 5 ■ GRE PRACTICE TESTS05-GRE-Test-2018_463-582.indd 534 12/05/17 12:14 pm