to the top

#5 - Only some strains of the tobacco plant are naturally

reop6780
LSAT Master
 
Posts: 266
Joined: Sat Jul 27, 2013 12:14 am
Points: 0

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?
Robert Carroll
PowerScore Staff
PowerScore Staff
 
Posts: 500
Joined: Fri Dec 06, 2013 7:18 am
Points: 436

reop,

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.

Robert
Wing yan
LSAT Novice
 
Posts: 4
Joined: Thu Jan 05, 2017 5:49 pm
Points: 4

Hi Powerscore,

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?


Thanks!
David Boyle
PowerScore Staff
PowerScore Staff
 
Posts: 853
Joined: Fri Jun 07, 2013 1:25 am
Points: 743

Wing yan wrote:Hi Powerscore,

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?


Thanks!



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,
David
Wing yan
LSAT Novice
 
Posts: 4
Joined: Thu Jan 05, 2017 5:49 pm
Points: 4

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 LSAT logic.
hassan66
LSAT Leader
 
Posts: 51
Joined: Thu Jul 19, 2018 7:38 pm
Points: 51

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."
Adam Tyson
PowerScore Staff
PowerScore Staff
 
Posts: 2690
Joined: Thu Apr 14, 2011 5:01 pm
Points: 2,503

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
hassan66
LSAT Leader
 
Posts: 51
Joined: Thu Jul 19, 2018 7:38 pm
Points: 51

Thank you Adam!
chiickenx
LSAT Apprentice
 
Posts: 7
Joined: Tue Apr 30, 2019 2:28 am
Points: 7

Hi, may someone please look over my Blind Review explanations?

In addition, I just want to ask two more questions regarding AC (E):

1. How should the word "resistant" be read in the AC? That is, should it be understood as an adjective? Or should it be read as a noun? This will be further elaborated below when I write out my thoughts for (E).

2. When and how can we infer causality on the LSAT?

Stimulus Summary:
~Disease AND infected with virus → (Strains of tobacco ←s→ naturally resistant to TMV)
Experiment #1
Resistant strains experimented w/ virus → levels of naturally occurring salicylic acid increased 5x
Nonresistant strains experimented w/ virus → ~levels of naturally occurring salicylic acid increased 5x
Experiment #2
50 nonresistant exposed to TMV
25 injected with SA
25 not injected with SA
A.
Idk if the plants could be cured…
B.
This sounds like a really good AC… i like this one better than (E) bc it has less burden of proof… it just says salicylic acid has something to do with something in virus resistance… it just we don't know exactly what the relationship between SA and a strain’s resistance is…
C.
If anything.. It seems like there is SA… its just not as much as the resistant strains…
D.
Oh idk a particular tobacco strain’s resistance is confirmed….
E.
On the first glance, this AC really stumped me. I was caught between this and (B)... To further elaborate, the first part of this AC is really good. However, the latter half is what’s really troubling since its full of ambiguity and philosophical conundrums…. Its sort of ambiguous what “and thus the strains made resistant to tobacco mosaic virus” means since it seems like this sentence can be construed in two ways:

(i) it could mean that the increase in Salicylic Acid (SA) production causes the tobacco plants to become resistant to the virus’s disease; or
(ii) it could mean that it causes the tobacco plant to produce a resistant to the virus.

Either way, the sentence has to deal with SA being a cause. Given as such, there is no support for this AC because the stimulus never says anything about causation since the stimulus never EXPLICITLY said that resistance is the effect of the increased SA production... The stimulus only says that SA and the virus’ disease have a strong correlation… This is why I chose (B) over (E).

this is the part I'm sort of confused on, and was wondering if I can get some feedback on this: In essence, the issue with (E) is that the stimulus says that some tobacco strains that produce SA five fold when infected with the virus are intrinsically resistant to the virus' disease; meanwhile, this AC claims that the resistance of the strain is caused by its capacity to produced an increased rate of SA. This is what my train of thought is... but is this similar to what PowerScore staff, Robert Carroll, said above (on Wed Dec 18, 2013 7:03 pm)?

NOTE:Understandably, the second experiment messes us up by saying that those who got injected with SA didn't have the disease, but those who didn’t get injected by SA got the disease. In normal everyday circumstances, we are groomed to think that SA caused the resistance… however, in the LSAT this is simply a flawed method of reasoning. Although, now that I am thinking about it, I wonder how causality could be inferred on the LSAT?

Thanks ahead of time!
James Finch
PowerScore Staff
PowerScore Staff
 
Posts: 711
Joined: Wed Sep 06, 2017 5:06 pm
Points: 708

Hi chiiken,

To answer your questions:

1. "Resistant" is an adjective in this instance, some of the plants are able to resist the virus, others cannot.

2. Here seems to be the problem, you misread the first experiment. In it, only the resistant plants saw a 5-fold increase in salicylic acid, while the non-resistant plants saw no increase. From this alone, we could infer that increased salicylic acid production is part of the resistance mechanism against the virus. This is further reinforced by the second experiment, which shows that even nonresistant plants can become resistant if injected with salicylic acid. So clearly salicylic acid plays a role in fighting the virus. That would be my Prephrase, and essentially exactly what (B) says. (E) is describing something that we absolutely don't know, which is how to make nonresistant plants resistant by having them increase their production; the second experiment dealt with plants that were injected with the salicylic acid, not producing it themselves. So only (B) works here.

Hope this clears things up!