Q24 - Mammals cannot digest cellulose and therefore

[ohthatpatrick]

Question Type:
Inference (most supported)

Stimulus Breakdown:
Mammals can't digest cellulose, so can't get glucose from wood. But mushrooms can. Once they turn the glucose from the wood into beta-glucans, mammals can digest them, and these beta-glucans actually help fight cancer by increasing immune-cell activity.

Answer Anticipation:
Inference questions test us on our ability to combine facts, usually using Conditional / Causal / Quantitative / Comparative wording.

This stimulus had some comparison/contrast stuff: mammals vs. mushrooms in terms of ability to extract glucose from wood.

But it also had Causal stuff: beta-glucans help with cancer by increasing immune-cell activity and the more the branching, the more the help.

Maybe the correct answer wants us to synthesize those last two ideas and say "the greater the degree of branching, the more immune-cell activity is increased". Mostly, we should stay flexible and beware strong or out of scope ideas.

Correct Answer:
C

Answer Choice Analysis:
(A) Extreme: obtain NO beneficial effects? Maybe chewing on cellulose makes our teeth hardier.

(B) Extreme: conditional. This is a reversal of what we were told. We were told "if the mushroom turn cellulose into beta-glucans, it can help with tumors".

(C) Looks good. The final two ideas, combined, seem to yield this idea (it doesn't HAVE to be true, but it's well supported).

(D) This might be tempting, but we can't definitively say whether immune cells kill cancer cells. Perhaps the beta-glucans increase immune cell activity, and the immune cells kill cancer cells. The author even allowed for this indirect causality by saying "beta-glucans don't prevent tumor growth by killing cancer cells DIRECTLY".

(E) Extreme: conditional. There's no way to say that EVERYTHING that can obtain glucose from wood can make beta-glucans. It might be a special talent of mushrooms.

Takeaway/Pattern: Just because I, with my pathetically deep knowledge of the test, was able to predict the exact answer doesn't mean we all should have done that. When you're reading an Inference paragraph, just remember to look out for conditional, causal, quantitative, and comparison/contrast language. If you can think of a way to combine two or more ideas (safely), then take a sec to consider that idea. But always stay flexible once you hit the answers. There may be many possible inferences.

#officialexplanation

[mrudula_2005]

Hi there,

What is wrong with (A)? What gets me about it is its mention of "eating cellulose." Mammals cannot digest cellulose and therefore cannot eat it. Sure, they can consume it indirectly by eating mushrooms, but they cannot be said to eat it themselves per se (as (A) indicates nonetheless).

That being said, can you help explain why (A) is wrong and why/how it can be said that Mammals DO obtain beneficial health effects from eating cellulose? If they just omitted that word "eating" I would not have been so tempted to pick it.

gracias!

[pinkdatura]

My assumption would be that there's a difference between digest and eat, "digest" as absorbed by stomach but eat as putting into mouth, maybe human can't process the cellulose but by eating it, or to say putting it into mouth there's still some health benefit, say moisturize your throat? I don't know.

Just some immature thought, waiting for more explanation

[da.chou]

You're assuming that mammals can't obtain beneficial health effects unless they can digest it. The stimulus doesn't say that at all, just that mammals can't digest cellulose - as you mentioned.

You don't have to prove an answer choice wrong, for inference / most strongly supported, you're just looking to eliminate answers that do not have to be true.

A.) Doesn't have to be true. Who knows, maybe mammals can get good health effects from eating cellulose - but you're right that these benefits won't come from digesting it...

B.) Too strong because maybe some shrooms can do all those things without using BGs. Just because a bunch of shrooms use BGs to do things doesn't mean to do those things you need BGs.

C.) This combines the last two sentences and is most strongly supported.

D.) The extracts don't do this but there is no saying what IC activity does or does not do in the absence of the extracts...

E.) Way too broad.

Some tricks: When I see a stimulus like this, I usually cry and if I'm pressed on time (Q24), I'll read the first sentence and the last sentence. Test writers count on that. If you read the first sentence only, A is your bear trap. If you read the last sentence only, D is your bear trap.

[mrudula_2005]

Some tricks: When I see a stimulus like this, I usually cry and if I'm pressed on time (Q24), I'll read the first sentence and the last sentence. Test writers count on that. If you read the first sentence only, A is your bear trap. If you read the last sentence only, D is your bear trap.

that was so unexpected and literally made me laugh out loud. haha, thank you for the help (and for the laugh) good luck to you

[ManhattanPrepLSAT2]

Great discussion! Just wanted to add 2 cents to clear up some points --

1) Yes, there is a difference between eating and digesting. Most humans can eat seaweed, for example, but only certain people (Japanese, mainly) can digest it.

2) Remember, for a "most strongly supported," the right answer is not going to be 100% provable, and your best approach is to get to the right answer by eliminating wrong ones (ones that are the clearly not probable based on text). I know this has been mentioned elsewhere but just wanted to reiterate it.

[lwilliams25619]

I still don't quite get why (B) is incorrect. As I read it, (B) says: If a type of mushroom does X, then the mushroom is able to use cellulose to make BG. From the stimulus it says some mushrooms can digest/use cellulose from wood and use it to make highly branched polymers which are a form of glucose called BG.

As I am typing this I think I've figured out why (B) is incorrect!

Is it wrong because of the word some in the stimulus and (B) implies that that must be true of ALL mushrooms that can do X? and also excluding the possibility that the mushroom isn't making some other chemical that is capable of X?

[vik]

B is wrong because the mushroom may be using another chemical to make the beta-glucans.

[ManhattanPrepLSAT2]

i agree w/vik --

(b) has a characteristic that is very common of incorrect answers to many types of LR questions -- it reverses the reasoning in the argument (in this case, in multiple ways). Another way of thinking about the issue is that the question attributes one possibility when there could have been many --

In this case, because some mushrooms can use cellulose to create something that eventually slow, etc. the growth of cancerous cells, the author is assuming that if something slows the growth of cancerous cells, it must have been derived from cellulose.

However, like vik said, the mushroom could get the beta-glucans from something other than cellulose. Furthermore, the extract could be of something totally different that exists in mushrooms, something that has nothing to do with beta-glucans, etc, but also happens to slow, etc. the growth of cancerous cells.