A Level Biology Practice Exam

What does scanning electron microscopy produce?

1. A two-dimensional image of internal cell structures

2. A three-dimensional image of the specimen surface

3. A series of light-based images of living cells

4. A chemical analysis of specimen elements

The correct answer is: A three-dimensional image of the specimen surface

Scanning electron microscopy (SEM) is specifically designed to produce high-resolution, three-dimensional images of the surface of specimens. Unlike other forms of microscopy, such as transmission electron microscopy which focuses on internal structures, SEM uses a focused beam of electrons that scans the surface of the sample. This process generates detailed images that highlight topographic features and surface textures in a way that resembles a three-dimensional representation. Therefore, the correct answer reflects the ability of SEM to showcase surface details, making option B the accurate choice. Other microscopic techniques might create two-dimensional images or analyze internal structures, but SEM is distinct in its capability to capture the intricate external morphology of samples.