Assessment and Qualifications Alliance (AQA) AS Biology Practice Exam

Pressing down firmly on a cover slip during microscopy is primarily focused on creating a thin layer for light passage. When observing microscopic specimens, it is essential for light to pass unobstructed through the sample so that clear images can be obtained. A thin layer of the specimen allows for better penetration of light, enhancing the resolution and details seen through the microscope.

If the sample is too thick or uneven, the light may scatter, resulting in distorted images or reduced clarity. Additionally, pressing the cover slip helps to minimize the thickness of the specimen, which is important for maintaining sharp focus and contrast while observing different cellular structures.

While preventing air bubbles and preserving specimen integrity may also be considerations during the microscopy process, the primary reason for pressing down on the cover slip revolves around facilitating optimal light transmission through a thin layer of the sample.