I don't even know how I got this one right since most of the answers looked correct to me.
The correct answer is B.
However, answer A, and E look as true as answer B.
what is wrong with these incorrect answers?
#5 - Only some strains of the tobacco plant are naturally
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This is a Must Be True, so any answer choice that is merely plausible, or that adds new information not in the stimulus, cannot be the correct choice. The correct answer has to be based only on the facts in the stimulus.
Answer choice (A) says that plants that have become diseased by infection with the virus can be cured by injecting them with salicylic acid. Look at the first sentence of the stimulus - it says that those strains that are naturally resistant never become diseased even when they are infected. So resistance, which the rest of the stimulus connects with salicylic acid, stops the plants from being diseased in the first place. We don't know if salicylic acid would help once the plants become diseased. Possibly it would, but since this is a Must Be True, we need to know for sure.
Answer choice (E) claims that it's possible to increase the production of salicylic acid in certain strains of tobacco plants and thus make those strains resistant to the virus. But the first group of plants, the ones which were infected and which increases salicylic levels naturally, were already resistant. So they didn't become resistant because of the experimental intervention. In the other experiment, the plants were not made to produce salicylic acid at all, but instead were injected with it. For answer choice (E) to be true, we would need a single experiment where two things occurred: production of salicylic acid in certain strains is increased, and those strains are made resistant to the virus. If the strains are already resistant, the latter condition can't be fulfilled; they can't be made resistant if they already are. Since neither experiment includes BOTH these things, answer choice (E) is not necessarily true.
Because answer choice (B) points out the connection in the stimulus between natural resistance and salicylic acid production, it is the correct answer. The other answers go beyond the stimulus, adding new information that is not legitimate in a Must Be True question.
I have problem understanding this question. I choose A because the stimulus said when resistant strains were infected with the virus experimentally, its salicylate acid will increase 5 folds (to help them fight against the virus) and in the 2nd experiment, it also said when nonresistance tobacco plants were exposed to the virus, and 25 of them were injected with salicylate acid showed no signs of infection, doesn't it mean that A, Tobacco plants that have become diseased by infection with the virus can be cured by injecting them with salicylic acid?
Hello Wing yan,
As Robert says above, we don't know that the acid can cure disease; it looks more like the acid can help the plants resist becoming diseased in the first place.
Hope this helps,
Thanks for the reply. I know it seems like redundant to ask the question of this sort again. But thanks for the confirmation that resistance doesn't mean cure. My mind still needs to fine tune with this LAST logic.
I was between B and E and I kept waffling until ultimately choosing E. I understand why B is correct, especially because the language isn't strong or forceful which makes it easier it must be true. But what confused me is that in experiment 2, 25 of the non resistant plants were injected with salicyclic acid and they didn't show infection. By injecting them with this acid, can't we assume that by adding more of this acid, the production of salicyclic acid was increased? Or, does production mean that it was naturally occurring? Would it have been correct if it had said, "by increasing the amount of salicyclic acid in certain strains of tobacco plants, these strains can be made resistant to tobacco mosaic virus."
I think you've got it, hassan. Production means the plants are making it themselves, and we don;t know that we can boost their ability to do that. I think your hypothetical alteration of answer E would make it a good answer.
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
Follow me on Twitter at https://twitter.com/LSATadam
Thank you Adam!
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