Explain how Vibrio cholerae causes cholera without apparent damage to the intestinal epithelium.
A. This microbe causes destruction of the cellular structures underneath the intestinal epithelium-this is what induces the watery rice-stool characteristic of the illness. This leaves the overlying intestinal epithelium intact.
B. This microbe directly invades the intestinal epithelial cells, but does not kill them. Instead, while multiplying inside them, it causes them to secrete large amounts of chloride ions. This induces water to follow by osmosis, resulting in the watery rice-stool characteristic of the illness.
C. This microbe attaches to the surface of intestinal epithelial cells, secreting an exotoxin that causes the epithelium to secrete large amounts of chloride ions. This induces large amounts of water to follow by osmosis, resulting in the watery rice-stool characteristic of the illness.
D. The inflammatory reaction to the presence of this microbe causes the watery rice-stool characteristic of the illness. Therefore, it's technically the immune response that initiates the disease, although this response is induced by the presence of the microbe on the intestinal epithelium.
Both Giardia lamblia and parvum are resistant to chlorine.
Indicate whether this statement is TRUE or FALSE.
Electron microscopes differ from light microscopes in that
A. electrons replace light.
B. electromagnets replace glass lenses.
C. resolution is higher.
D. magnification is higher.
E. All of the choices are correct.
Specimens can be observed at the atomic level using a(n)
A. scanning electron microscope.
B. transmission electron microscope.
C. atomic force microscope.
D. All of the choices are correct.
E. None of the choices is correct.
The microscope that allows the specimen to appear three-dimensional is the
A.
phase contrast microscope.
B.
interference microscope.
C. fluorescence microscope.
D. dark-field microscope.
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