Q22 - Viruses can have beneficial effects

[debbie.d.park]

This seems to be a "must be false" question, and I hesitated between D and E. Can you please explain why E is a better answer? Many thanks!

[ManhattanPrepLSAT1]

This is a "Must be False" question!

Now that our task is clear, the more difficult task of sorting through these answer choices is next...

We know that some viruses kill more-complex microorganisms, some of which are deadly to humans. In other words, some viruses are beneficial to humans.

Thus, it must be false that no viruses are beneficial to humans. That is why answer choice (E) must be false.

(A) could be true. Notice the word "some." This makes it very easily compatible with the stimulus.
(B) could be true. Notice the word "some." This makes it very easily compatible with the stimulus.
(C) could be true. Notice the word "some." This makes it very easily compatible with the stimulus.
(D) could be true. Notice the word "some." This makes it very easily compatible with the stimulus.

Each of the incorrect answers is all weak enough to be consistent with the stimulus. In order for answer choices (A) - (D) to be something that must be false, we would need much stronger information in the stimulus.

So for example, in order for answer choice (D) to be something that must be false, the stimulus must establish that no viruses that fail to kill other viruses are beneficial to humans.

Does that help clear this one up? Let me know if you'd still like me to help you further with it!

[all_boost]

The problem I had with this question, and the foregoing explanation, is that not all viruses are deadly, according to the facts. Yes it must be false that no viruses are beneficial to humans, because we know that some are. But I don't quite see how it's safe to assume that there are necessarily some viruses that become deadly also have beneficial effects. To put it more simply, I see it like this:

1- Members of group 1 can potentially have quality A (beneficial). Some of whom for example have subquality A~.
2- Members of group 1 also commonly develop quality B (deadly).

Cannot be true (correct answer):
3- No member of group 1 who has quality B has quality A.

I can't see how the correct answer would therefore obtain... If 1 member of group 1 has quality A and only quality A (which would satisfy point 1), why can't every other member of group 1 have only quality B? (this would in turn render point 3 a "could be true" scenario).

It seems, to me, akin to drawing an inference from a "Most" claim and a "some" claim...

Help?

[timmydoeslsat]

The problem I had with this question, and the foregoing explanation, is that not all viruses are deadly, according to the facts. Yes it must be false that no viruses are beneficial to humans, because we know that some are. But I don't quite see how it's safe to assume that there are necessarily some viruses that become deadly also have beneficial effects. To put it more simply, I see it like this:

We do not know for a fact that there are some viruses that are not deadly. We are told that some are deadly. This could mean anywhere from 1 virus to all viruses. We do not know that there are viruses that are not deadly from the stimulus.

We do necessarily know that some viruses that are deadly are beneficial to humans.

We know that some viruses are deadly to more-complex microorganisms. Some of these more-complex microorganisms are deadly to humans.

So we do have a case of some deadly viruses that are beneficial to humans. These viruses are killing things that are deadly to humans.

[all_boost]

Ah yes, I understand now. Thank you!

[griffin3575]

This is a must be false question. So four of the answer choices could be true, and one answer choice cannot be true(must be false). Let's start by gathering the facts of the stimulus.

1. Some viruses are beneficial, because they kill some microorganism deadly to humans.
2. Replacing some of a simple structured virus's atoms can make it deadly to humans.
3. Random mutations like #2 happen all the time, so any virus can become dangerous.

Now in my opinion, it is better to work wrong to right here, eliminating answers that could be true. Answer choices that introduce new information not discussed in the stimulus are not something we can pass judgement on, so they could be true! How can you infer an answer choice is false if the stimulus never discusses it?

(A) - The stimulus tell us that random mutations of simply structured/beneficial viruses can be deadly to humans. Answer choice A is simply the reverse of that statement. The reverse, random mutations of deadly viruses can make them beneficial viruses, is never discussed, so it could be true. Eliminate.

(B) - The wording of B is what makes this answer choice challenging. "Some organisms of greater complexity than viruses", could be talking about a host of other organism. But the stimulus gives us a specific example of an organism that has a greater complexity then viruses: some microorganisms. So answer choice B could be read as: "Some microorganisms are no more likely than viruses to undergo significant alterations through random mutation". The likelihood that a virus will undergo random mutation is never discussed, so how can we know whether viruses are more likely to undergo random mutation then some more complex organisms? Therefore, B could be true. Eliminate.

(C) - The stimulus tells us that SOME more complex microorganisms are deadly to humans. Does this mean that ALL microorganisms are deadly to humans? No! It is entirely possible that while some microorganisms are deadly to humans, there is at least one microorganism that is beneficial to humans. So, C could be true. Eliminate.

(D) - So what? Imagine that a virus does indeed fail to kill another virus that is deadly to humans. Does that mean that that virus is not beneficial to humans? Of course not. While this virus may not kill a more deadly virus, perhaps it is killing a more complex non-virus microorganism that is deadly to humans. Thus, it could be true that this non-virus killing virus is beneficial to humans because its killing other dangerous non-virus microorganisms. Eliminate.

(E) - It took me a couple of reads to understand exactly what E was saying. E can be translated into: "A virus that is deadly to a more complex organism is never beneficial to humans". But wait, aren't some microorganisms more complex than viruses, and can't some viruses kill these more complex microorganisms? Absolutely. It says so directly in the stimulus. So, it must be true that there are at least some viruses that are deadly to a more complex organism and are also beneficial to humans. Therefore, E must be false and is our answer.

[jenniferreisig]

I see the point made about A-D all containing the word "some", making them too weak for our MBF. This was a helpful point.

When I was working through the question I choice (E) because it negated the necessary condition - being beneficial to humans. In the stimulus it states some viruses that kill organisms with greater complexity (KOGC) makes it possible for viruses to beneficial to humans (BH). KOGC ---> BH. Answer (E) restated states IF any virus is deadly to organisms of greater complexity THEN it is not beneficial. KOGC ---> ~BH. That can't be true because it completely reverses the argument made in the stimulus by negating the necessary condition. Using a conditional approach took me some time but helped me get to the conclusion that (E) states the opposite of what we are told in the stimulus - being deadly to organisms of greater complexity is what makes viruses beneficial. Hopefully next question like this I'll move a little faster