Which reason best explains why dead specimens must be used with transmission electron microscopes?

• A. Live specimens are too small to be visualized by electron microscopes.
• B. The preparation process requires dehydration and embedding, which kills the specimen.
• C. The high magnification causes living cells to divide uncontrollably.
• D. Transmission electron microscopes cannot focus on moving objects.

Answer: (B)

Verified step by step guidance

1. Understand the nature of transmission electron microscopy (TEM), which uses a beam of electrons to create highly detailed images of specimens at very high magnifications.
2. Recognize that the preparation process for TEM involves several steps such as dehydration, embedding in resin, and ultrathin sectioning, all of which are necessary to allow electrons to pass through the specimen and produce a clear image.
3. Note that these preparation steps are harsh and incompatible with living cells, as dehydration removes water essential for life and embedding involves chemicals that kill the specimen.
4. Consider that live specimens cannot survive the vacuum environment inside the electron microscope, which is required to prevent electron scattering and maintain image quality.
5. Conclude that because of these preparation and environmental requirements, only dead specimens can be used with transmission electron microscopes.