In the plaque assay for bacteriophages, A. only temperate phages may be used. B. the plaque is an opaque area caused by a high concentration of virus. C. the plaque is a clear zone caused by a zone of lysis. D. coculture with bacteria is not required.

The correct answer is C. In the plaque assay for bacteriophages, the plaque is a clear zone caused by a zone of lysis.

Explanation:

The plaque assay is an approach used for titering bacteriophage stocks or determining the quantity of infectious virus in a sample. Plaques are visualized if you spot the phage on a lawn of growing compatible bacteria. Each plaque indicates an initial infection with one phage followed by lysis of neighboring bacteria in the lawn. Only viruses that cause visible damage of cells can be assayed in this way. The plaque assay is used to determine viral titer as plaque-forming units per ml so that known amounts of virus can be used to infect cells during subsequent work.

In the plaque assay for bacteriophages, the plaque is a clear zone caused by a zone of lysis.