Nhận biết (M1)

Some pharmaceuticals contain titanium dioxide nanoparticles (TiO2-NPs) which can lead into waterways and soils via wastewater. In 2014 study, Cheng Tan and Wen-Xiong Wang found that TiO2-NPs can accumulate in the bodies of water fleas (Daphnia magna). While bioaccumulation of manufactured nanoparticles may be inherently worrisome, it has been hypothesized that TiO2-NP bioaccumulation in invertebrates like D. magna could serve a valuable proxy role, obviating the need for manufacturers to conduct costly and intrusive sampling of vertebrate species—such as Chinook salmon (Oncorhynchus tshawytscha), commonly used in regulatory compliance testing—for nanoparticle bioaccumulation, as environmental protection laws currently require.

Which finding, if true, would most directly support the hypothesis?

• A.

  In comparable environments, D. magna and O. tshawytscha display comparable rates of TiO2-NP uptake.

• B.

  Compared with O. tshawytscha, D. magna can tolerate significantly higher TiO2-NP concentrations.

• C.

  It is easier to detect low and harmless concentrations of TiO2-NPs in D. magna than it is to detect high and harmful concentrations of TiO2-NPs in O. tshawytscha.

• D.

  TiO2-NP concentrations in D. magna tend to vary more from individual to individual than do TiO2-NP concentrations in O. tshawytscha when the species are exposed to similar levels of TiO2-NPs.