Question

A specimen has been prepared for viewing with a transmission electron microscope, using uranyl acetate as a negative stain. The area stained by the uranyl acetate will be ________ electron dense compared to specimen itself.

more

equally

less

Answer 1

Correct ans is A. Area stained by uranyl acetate will be more electron dense compared to specimen itself.

Basically, in negative staining the required specimen is not stained but the background or the surrounding is stained. The negative stain does not come in contact with the specimen.This produces contrast between the two and the specimen can be seen.
So, the area stained i.e the background will tend to scatter the electrons more strongly and this is called electron dense. More the stronger scattering of electrons, more electron dense will be the area. Hence this area i.e the background appears dark and the specimen that tends to scatter fewer electrons appears bright. This produces contrast between the specimen and the background allowing better visibility.