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29 May 2023, 06:38
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
25% (02:24) correct
75%
(02:35)
wrong
based on 16
sessions
History
Date
Time
Result
Not Attempted Yet
Formerly, it was believed that beverages with caffeine exerted a stimulant effect by inhibiting production of the enzyme phosphodiesterase, but this cannot be the case. It is true that elevated concentrations of AMP can lead to increased neuron firing and consequently behavioral stimulation, and that phosphodiesterase acts to break down the chemical AMP. It is now known, however, that the caffeine concentrations required to inhibit the production of phosphodiesterase are higher than the concentrations at which caffeine’s stimulant effects in the subject becomes apparent.
The conclusion in the first sentence rests on which of the following assumptions?
(A) Some beverages contain a stimulant in concentrations lower than required to inhibit the production of phosphodiesterase.
(B) Phosphodiesterase does not inhibit stimulation by some means other than breaking down AMP.
(C) The concentration of caffeine required for a stimulant effect is not much higher than previously thought.
(D) Caffeine does not act directly to break down AMP.
(E) Caffeine is the only stimulant in caffeinated beverages.
The conclusion in the first sentence rests on which of the following assumptions?
(A) Some beverages contain a stimulant in concentrations lower than required to inhibit the production of phosphodiesterase.
(B) Phosphodiesterase does not inhibit stimulation by some means other than breaking down AMP.
(C) The concentration of caffeine required for a stimulant effect is not much higher than previously thought.
(D) Caffeine does not act directly to break down AMP.
(E) Caffeine is the only stimulant in caffeinated beverages.
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29 May 2023, 06:38
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Best answer: (A)
Identify the conclusion and the premise(s):
Premise: Phosphodiesterase acts to break down the chemical AMP.
Premsie: Elevated concentrations of AMP can lead to increased neuron firing and consequently behavioral stimulation.
Premise: The caffeine concentrations required to inhibit the production of phosphodiesterase are higher than the concentrations at which caffeine’s stimulant effect in the subject becomes apparent.
Conclusion: It cannot be the case that caffeinated beverages exert a stimulant effect by inhibiting production of the enzyme phosphodiesterase.
Explanations:
Identify question type and give some tips:
The gap in the logic is the assumption that caffeinated beverages cannot stimulate a certain way, they would have to contain a concentration of caffeine lower than the threshold to do so. The premises establish a link between phosphodiesterase and AMP breakdown, between high concentratins of AMP and increased neuron firing, and between neuron firing and behavioral stimulation. But if high concentrations of caffeine or another stimulant can cause phosphodiesterase inhibition, they most certainly could cause a stimulant effect—perhaps an additional one to what they already do.
Scan each answer choice by eliminating progressively each “wrong” answer to finish with the “best” answer:
(A) outlines at least a part of this assumption. (B) and (D) stray away from the scope of the argument; the effects of caffeine on phosphodiesterase are at stake, not of either on AMP. Likewise, it matters not if formerly we thought the concentration of caffeine required for a stimulant effect was even lower; it is still lower than the concentration required for the chemical reaction at stake, so choice (C) is wrong. Finally, even if there were other stimulants in caffeinated beverages, they might have no effect on phosphodiesterase themselves, so we need not assume (E).
Identify the conclusion and the premise(s):
Premise: Phosphodiesterase acts to break down the chemical AMP.
Premsie: Elevated concentrations of AMP can lead to increased neuron firing and consequently behavioral stimulation.
Premise: The caffeine concentrations required to inhibit the production of phosphodiesterase are higher than the concentrations at which caffeine’s stimulant effect in the subject becomes apparent.
Conclusion: It cannot be the case that caffeinated beverages exert a stimulant effect by inhibiting production of the enzyme phosphodiesterase.
Explanations:
Identify question type and give some tips:
The gap in the logic is the assumption that caffeinated beverages cannot stimulate a certain way, they would have to contain a concentration of caffeine lower than the threshold to do so. The premises establish a link between phosphodiesterase and AMP breakdown, between high concentratins of AMP and increased neuron firing, and between neuron firing and behavioral stimulation. But if high concentrations of caffeine or another stimulant can cause phosphodiesterase inhibition, they most certainly could cause a stimulant effect—perhaps an additional one to what they already do.
Scan each answer choice by eliminating progressively each “wrong” answer to finish with the “best” answer:
(A) outlines at least a part of this assumption. (B) and (D) stray away from the scope of the argument; the effects of caffeine on phosphodiesterase are at stake, not of either on AMP. Likewise, it matters not if formerly we thought the concentration of caffeine required for a stimulant effect was even lower; it is still lower than the concentration required for the chemical reaction at stake, so choice (C) is wrong. Finally, even if there were other stimulants in caffeinated beverages, they might have no effect on phosphodiesterase themselves, so we need not assume (E).
30 May 2023, 11:26
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Can anyone please explain why A is the correct answer? i am out of my wits for this question
