11
40) Acetylcholine is a chemical messenger that
A) activates the presynaptic membrane to make it permeable to ions that conduct an impulse.
B) inactivates the presynaptic membrane to make it impermeable to certain ions that conduct an impulse.
C) activates the postsynaptic nerve cell by fitting into a specific receptor and changing the permeability of
the cell membrane to certain ions.
D) inactivates the postsynaptic membrane to make it impermeable to certain ions that conduct an
impulse.
41) Actylcholinesterase acts to change acetylcholine to
A) acetic acid, water and choline.
B) water and choline.
C) water and acetic acid.
D) acetic acid and choline.
42) Which of the following will make the most effective poison for rats and mice?
A) ethyl alcohol, LD50 = 2.08 g/kg
B) acetaminophen, LD50 = 0.340 g/kg
C) ethylene glycol, LD50 = 0.00686 g/kg
D) ricin, LD50 = 0.000005 mg/kg
43) Which of the following statements about LD50 is NOT correct?
A) The LD50 for a substance is the dose that will kill 50% of test subjects.
B) A substance with a low LD50 is more toxic than a substance with a high LD50.
C) The LD50 value for a mouse will be the same as the LD50 value for a human.
D) The LD50 value will change, depending upon how the substance is administered.
44) The organ most used for the detoxification of poisons in the human body is the