Q. 45

[admin]

The main difference is that the passage describes the hydrolysis (lysis is the splitting apart of any two things) of ACh which makes answer choice D probable. But the passage never discusses how AChesterase is controlled thus suggesting hydrolysis for the enzyme is pure conjecture. If D did not exist as an option then B would be the only other possibility. But D is definitely the best option.

[admin]

I suppose that a combination of the passage and the 3 graphs in Figure 2 are helpful to solving this problem.

[jellywing_2058]

The first part of option A is correct, however not the second part for eserine. What needs to bind to the ACh receptor is acetylcholine.

Acetylcholine makes the channel open. It is not mentioned anywhere that eserine has the same effect as acetylcholine on the ACh receptor.

Therefore, by binding to the receptor, eserine is blocking the acetylcholine; the channels cannot open, leading the cell to remain polarized. This contradicts the Graph C.

[admin]

bump

[dshastr13244]

why does eserine increase the amplitude of the action potential. I assume an AP is still taking place, yet prolonged and higher amplitude because the control graph shows the threshold stimulus at much lower than 1 mV while the amplitude of the depolarization of eserine is almost 3 mV. Does this mean that artificial ways of increasing depolarization via a ACh-esterase inhibitor does not have to occur in a all or none fashion?