Which of the following measurements is correctly matched with microorganisms of that size?

• A. Viruses: 10–100 micrometers (µm)
• B. Protozoa: 10–100 nanometers (nm)
• C. Fungi: 0.1–1 nanometers (nm)
• D. Bacteria: 1–5 micrometers (µm)

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the typical size ranges of different microorganisms. Viruses are generally much smaller than bacteria and protozoa, usually measured in nanometers (nm), not micrometers (µm).
2. Step 2: Recall that protozoa are relatively large single-celled organisms, often measured in micrometers (µm), not nanometers (nm), since nanometers are too small for these cells.
3. Step 3: Recognize that fungi, especially their hyphae and spores, are also measured in micrometers (µm), not in nanometers (nm), because nanometers are on the scale of molecules and viruses.
4. Step 4: Know that bacteria typically range from about 1 to 5 micrometers (µm) in size, which fits the given measurement for bacteria in the problem.
5. Step 5: Compare each given size range with the known typical sizes of microorganisms to identify which pairing is correct, focusing on the units (nm vs. µm) and the size scale appropriate for each group.