An electron microscope must use electromagnet "lenses" shaped like donuts to direct the electrons onto the specimen. Why?
A. Electrons are particles-there are also particles in air. Without a vacuum, the electrons would strike and be scattered by the atoms/particles within the air.
B. Because electrons are highly radioactive, and the chamber must be completely sealed to prevent them from escaping and contaminating the lab area.
C. This is the method for fixing the specimen to the slide grid for an electron microscope. Without fixing the specimen by vacuum, it would slide off and we wouldn't be able to visualize it.
D. All of the above are true.
A
You might also like to view...
Which pigment is always present when a dominant allele (A) is present?
a. Red b. Yellow
Tunicates have which of the following traits?
A. radial symmetry B. incomplete digestive tract C. asymmetry D. pharyngeal slits E. endothermic
A species has n=4 chromosomes. Genes on the same chromosome have a minimum recombination recombination rate of:
a. 100% b. 75% c. 50% d. 25% e. 0%
Red-green color blindness is an X-linked recessive trait (dominant allele denoted as C). Two normal-vision parents have a color-blind son. The genotypes of the father, mother, and son are respectively _____,_____,_____.
Fill in the blank(s) with the appropriate word(s).