119. A conventional light microscope allows us to magnify cells up to 1000 times and to resolve
details as small as ________.
A. 200 μm
B. 200 nm
C. 0.2 nm
D. 20 nm

Detailed Explanation:

A conventional light microscope is a fundamental tool in biological sciences, allowing scientists to magnify and observe cells and small structures. However, there are physical limits to what this microscope can resolve, based on the wavelength of visible light.

Magnification:

• A conventional light microscope can typically magnify objects up to 1000x without significant distortion.

Resolution:

• The resolution of a microscope is the smallest distance between two points that can still be distinguished as separate.

• For light microscopes, this limit is about 200 nanometers (nm) due to the diffraction limit of visible light.

• Structures smaller than 200 nm, such as ribosomes, viruses, or protein complexes, cannot be resolved with this type of microscope.

Option Analysis:

• A. 200 μm – Too large; 200 micrometers is visible to the naked eye.

• B. 200 nm – Correct; this is the practical resolution limit for a conventional light microscope.

• C. 0.2 nm – This is the scale of atomic resolution, which requires electron microscopy, not light microscopy.

• D. 20 nm – Below the diffraction limit of light; also requires advanced methods like super-resolution microscopy.

Correct Answer:

B. 200 nm

This value represents the smallest detail a conventional light microscope can resolve, making it a crucial limit for cell and molecular biology observations.