PT 21.S3.Q16

MambaMentality93

Can anybody help me with this question, because it is driving me crazy.
Why is B wrong? The stimulus clearly states "anygiven individual molecule of substance can activate..." how is this statement not supporting B?
And how can C be right? how can we be sure that no sweeter substance will be found? What about half a molecule for instance?Are we supposed to assume that it is impossible to activate a receptor with less than a whole molecule?
This question is truly infuriating, any help would be greatly appreaciated!

Admin Note: https://7sage.com/lsat_explanations/lsat-21-section-3-question-16/

Chris Nguyen

Hey there!

This question is hard because the stimulus has very confusing language. Lets break down what it is actually saying.

Sentence 1: Researchers are saying that we can taste sweetness by activating a sweetness receptor

Sentence 2: Researchers also say that a molecule can activate at most one sweetness receptor, and the sweeter the substance, the less molecules of the substance it takes for the receptor to activate.

Sentence 3: We have substance X. Only one molecule of substance X is needed to activate any sweetness receptor.

So what can we conclude from these sentences? We can conclude the no substance can be sweeter than substance X, specifically because of the information in sentence 1 and 2. AT MOST, one molecule can activate 1 sweetness receptor. The sweeter our substance, the less molecules it takes to activate the receptor. So, since substance X takes only one molecule to activate a sweetness receptor, and that's the absolute most receptors you can activate, it's true that we won't find any substance sweeter than substance X, which is what (C) states.

Lets have a look at B. How can we be so sure that everything is able to activate sweetness receptors? You say the stimulus states "any given individual molecule of substance can activate" but you're not citing the whole phrase. The whole things says "any given individual molecule of substance can activate at most one sweetness receptor" We're given a maximum of how many receptors we can activate, not a minimum number. So we are able to say that such a molecule has the possibility of activating no sweetness receptors at all. Now, if it said "Any given individual molecule of substance is able to activate a sweetness receptor" then yes. That would be supported. But the stimulus just doesn't say that. There is a difference between the two sentences.

Regarding your questions with C - a molecule is a smallest particle we can get to without breaking the substance into it's atoms, so given that, we aren't able to use a half molecule. It just wouldn't work scientifically. A half molecule would no longer be identical to the substance we have.

But lets say you didn't know that. You could still get this question correct.

We know from sentence 2 that at most, a molecule can activate one sweetness receptor. If we had a substance that half a molecule would activate a sweetness receptor, we would get a contradiction. It would mean that a whole molecule of that substance would be able to activate two sweetness receptors. You can't have that because we know that AT MOST, a molecule can activate 1 receptor.

Also, say that we have a substance that .6 of a molecule is able to activate the receptor. You might say that 1 molecule of that substance wouldn't be able to activate 2 sweetness receptors but would still be sweeter than the substance found by the scientists bc of it's ability at .6 to activate a sweetness receptor. This still would be in contradiction because 3 of these molecules would be able to active 5 sweetness receptors, which is in contradiction to the rule that at most, 1 molecule can only activate 1 sweetness receptor. How can you have 3 molecules activating 5 receptors if at max only 1 molecule can activate 1 receptor? So even if you don't know what a molecule is you can get this question correct.