Question

The average diameter of a prokaryotic cell is

• A. 1-10 micrometer
• B. 10-100 micrometer
• C. 1-10 nanometer
• D. 10-100 nanometer

Hint:

Remember the standard size hierarchy of life:
- Viruses: $20\text{--}400\,\text{nm}$
- Prokaryotes: $1\text{--}10\,\mu\text{m}$
- Eukaryotes: $10\text{--}100\,\mu\text{m}$
Keep in mind that $1\,\mu\text{m} = 1000\,\text{nm}$.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Prokaryotes (bacteria and archaea) are single-celled organisms that lack a membrane-bound nucleus and other complex internal organelles.
As a consequence of their simpler structural organization, prokaryotes are significantly smaller than eukaryotic cells.

Step 2: Detailed Explanation:
Let us analyze the standard scale of biological cells:
- Prokaryotic cells: Most bacteria have an average diameter or length ranging from $1$ to $10\,\mu\text{m}$ (micrometers). For example, *Escherichia coli* is typically about $1\text{--}2\,\mu\text{m}$ long.
- Eukaryotic cells: These are structurally larger and more complex, typically ranging from $10$ to $100\,\mu\text{m}$ in diameter.
- Nanometer scale ($1\text{--}100\,\text{nm}$): This scale is far too small for any living cell. It is the scale of individual biomolecules (like DNA and proteins) and viruses (which typically measure $20\text{--}400\,\text{nm}$).

Step 3: Final Answer:
Therefore, the average diameter of a prokaryotic cell lies in the range of $1\text{--}10\,\mu\text{m}$, which corresponds to option (A).