Question

If reasonably pure preparations of the virus are available, the number of viruses present may be determined by

A) photocolorimetry.
B) gas chromatography.
C) light microscopy.
D) electron microscopy

Answer 1

The number of viruses present in pure preparations can be determined by electron microscopy, which allows scientists to view the surface and internal structures of virions that are otherwise too small to be seen with a light microscope.

Step-by-step explanation:

If reasonably pure preparations of the virus are available, the number of viruses present may be determined by electron microscopy. Most virions, or single virus particles, are too small to be seen with a light microscope, with dimensions generally ranging from about 20 to 250 nanometers. Not until the development of the electron microscope in the late 1930s could scientists view viruses such as the tobacco mosaic virus and others. This technology allows for the observation of the surface structure of virions by both scanning and transmission electron microscopy, while the internal structures of the virus can be observed through transmission electron microscopy.