Why must the sample placed on a microscope slide be very thin when preparing it for observation under a light microscope?

• A. To prevent the specimen from drying out during observation
• B. To avoid contamination from the slide surface
• C. To increase the magnification power of the microscope
• D. To allow light to pass through the specimen for clear visualization

Answer: (D)

Verified step by step guidance

1. Understand the basic principle of how a light microscope works: it uses light to illuminate the specimen, and the light must pass through the sample to form a clear image.
2. Recognize that if the specimen is too thick, light cannot effectively pass through it, resulting in a blurry or unclear image under the microscope.
3. Consider that a thin sample allows light to transmit through the cells or structures, enabling better contrast and detail to be observed.
4. Note that preventing drying out or contamination, and increasing magnification power, are not directly related to the thickness of the sample in this context.
5. Conclude that the primary reason for placing a very thin sample on the slide is to allow light to pass through the specimen for clear visualization.