Nhận biết (M1)

Biologist Rosanna Alegado believes that we might learn how multicellular organisms developed from single-celled ones if we understand why the single-celled organism Salpingoeca rosetta, the oldest living relative of animals, sometimes forms colonies of cells. Alegado and colleagues reviewed data from many studies of how S. rosetta responds when exposed to another type of single-celled organism, bacteria, including Iftikhar Ahmed's work with Algoriphagus baritolerans bacteria and William C. Nierman's work with Caulobacter crescentus bacteria. Alegado and colleagues concluded that A. baritolerans might have played a role in the development of multicellular organisms.

Which finding, if true, would most directly support Alegado and colleagues' conclusion?

• A.

  Neither Ahmed using A. baritolerans nor Nierman using C. crescentus found that S. rosetta tended to form colonies when exposed to these bacteria.

• B.

  Ahmed found that S. rosetta tended to form colonies when exposed to A. baritolerans, whereas several studies involving other species of bacteria, including Nierman's study using C. crescentus, showed no such link.

• C.

  Both Ahmed using A. baritolerans and Nierman using C. crescentus found that S. rosetta tended to form colonies when exposed to these bacteria.

• D.

  Ahmed found that existing colonies of S. rosetta were unaffected by exposure to A. baritolerans, whereas several studies involving other species of bacteria, including Nierman's study using C. crescentus, showed that existing colonies of S. rosetta stopped growing when exposed to these bacteria.