Final answer:
The unit used to measure most viruses is the nanometer (nm) (option d) , with typical virus sizes ranging from 20 nm to 900 nm. As viruses are ultramicroscopic and generally smaller than bacteria and cells, electron microscopes are used to visualize them.
Step-by-step explanation:
The unit used to measure most viruses is d. Nanometer (nm). Viruses are ultramicroscopic, with typical sizes ranging from 20 nm to 900 nm. To provide some perspective, an object must be about 100 micrometers (µm) to be visible without a microscope, which means viruses are much smaller than this threshold.
Additionally, a typical bacterium measures approximately 1 µm, and a virus is usually 10 times smaller than a bacterium. Electron microscopes are required to effectively visualize viruses due to their minute size.
For reference:
- A kilometer (km) is 1,000 meters (m).
- A milligram (mg) is one-thousandth of a gram (g).
- A nanosecond (ns) is one-billionth of a second (s).
- A centiliter (cL) is one-hundredth of a liter (L).
Understanding the relative sizes of microscopic objects and the units used to measure them is crucial when dealing with microbiological subjects.