9
lesson pretestMultiple Choice

Pretest

Question 9 • CMS 2026-2027 Biology CREDIT RECOVERY

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

Answer
A
Specimens are placed in a vacuum.
B
Electrons pass over the specimen.
C
The image that is produced is two dimensional.
D
The lights that are used are harmful to the specimens.

Explanation

A transmission electron microscope operates in a vacuum so electrons can travel through the instrument without being scattered by air molecules. Living specimens cannot survive in that vacuum, so the specimens must be dead. The two-dimensional image does not explain why the specimen must be dead.

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