Which of the following microscope types would be least useful in viewing unstained living cells?

• A. Phase-contrast microscope.
• B. Differential interference contrast microscope.
• C. Bright-field microscope.
• D. Dark-field microscope.

Answer: (C)

Verified step by step guidance

1. Understand the purpose of each microscope type: Bright-field, Phase-contrast, Differential interference contrast, and Dark-field.
2. Bright-field microscopes require staining to enhance contrast, making them less suitable for viewing living cells, as staining typically kills cells.
3. Phase-contrast microscopes enhance contrast in unstained cells by amplifying differences in refractive index, making them ideal for viewing living cells.
4. Differential interference contrast (DIC) microscopes use polarized light to produce high-contrast images of unstained specimens, suitable for living cells.
5. Dark-field microscopes illuminate the specimen from the side, making unstained cells appear bright against a dark background, useful for observing living cells.