Need Help on an LSAT LR Question. Thanks!

joyinca

Anybody would like share your opinion of the following LR question?

Many important types of medicine have been developed from substances discovered in plants that grow only in tropical rain forests. There are thousands of plant species in these rain forests that have not yet been studied by scientists, and it is very likely that many such plants also contain substances of medicinal value. Thus, if the propical rain forests are not preserved, important types of medicine will never be developed.

Which one of the following is an assumption required by the argument?
(A) There are substances of medicinal value contained in trpopical rain forest plants not yet studied by scientists that differ from those substances already discovered in tropical rain forest plants.
(B) Most of the tropical rain forest plants that contain substances of medicinal value can also be found growing in other types of environment.
(C) The majority of plant species that are unique to tropical rain forests and that have been studied by scientists have been discovered to contain substances of medicinal value.
(D) Any substance of medicinal value contained in plant species indigenous to tropical rain forests will eventually be discovered if those species are studied by scientists.
(E) The tropical rain forests should be preserved to make it possible for important medicines to be developed from plant species that have not yet been studied by scientists.

joyinca

为啥没人回？

爱吃醋的熊

joyinca 发表于 2013-10-1 07:22
为啥没人回？

The correct answer is E?

366939808

I choose A.

366939808

爱吃醋的熊 发表于 2013-10-7 07:04
The correct answer is E?

nothing to do with SHOULD

joyinca

366939808 发表于 2013-10-8 20:13
I choose A.

是2010年10月SECTION 4第20题。答案是A。366939808解释一下？

爱吃醋的熊

joyinca 发表于 2013-10-9 09:24
是2010年10月SECTION 4第20题。答案是A。366939808解释一下？

sorry, I made mistake。。。。anyway, raised your question in our Toronto local forum and specialist answered me as follows:Necessary assumption questions can be tricky. First step is to find the core:

Very likely that undiscovered rainforest plants have medicinal value ---> If rainforest not preserved, important types of medicine won't be developed

There seem to be quite a few gaps. The premise talks of plants with "medicinal value." To go to "important types of medicine," you really skip a few steps. Because this is a necessary assumption question, however, I'm not going to spend too much time on predicting the answer.

(A) points to a different necessary assumption than I considered above. The premise only tells us that the undiscovered plants have "medicinal value." But if they have the same medicinal properties as existing plants (17 different species of the tylenol plant), we're not in any danger of missing out on medicines. If you don't believe me, apply the negation test:

"There are NO substances of medicinal value in the plants that haven't been studied that differ from the ones we already know about."

If that's the case, then fire up the chainsaws. We've got all the species of Advil plant that we need. Because this destroys the argument, (A) is the necessary assumption.

The wrong answers:

(B) is an opposite. If most of the plants are growing elsewhere, then why worry about the rainforests?

(C) is either a premise booster or out of scope. It's a premise booster because we already know it's likely that the undiscovered plants contain substances of medicinal value. It's out of scope because we're concerned about the undiscovered plants and this tells us more about the ones that have been studies.

(D) is worded too strongly to be a necessary assumption. It's not necessary that we discover ANY substance in a plant scientists study. Remember that when you negate ANY, you get "not every." That won't destroy the argument as long as they will discover some of them.

(E) is tempting but is out of scope. The word should is a giveaway. The stimulus never says anything about what should or shouldn't happen. The argument is purely descriptive: if we don't protect the rainforest, this thing will happen. Any attempt to tell me what should happen requires an assumption that the argument doesn't make (important medicines should be protected).

I hope this helps on this question. Let me know if you have any questions.

爱吃醋的熊

366939808 发表于 2013-10-8 20:14
爱吃醋的熊 发表于 2013-10-7 07:04
The correct answer is E?

thanks buddy, your answer is completely right。。。。I am preparing for Dec LSAT in Toronto, hardcore study is continuing。。。。

joyinca

爱吃醋的熊 发表于 2013-10-10 04:14
thanks buddy, your answer is completely right。。。。I am preparing for Dec LSAT in Toronto, hardc ...

多谢！同时考，加油加油！争取一次过！

keruan

just negative A,you get  "There are NO substances of medicinal value contained in trpopical rain forest plants not yet studied by scientists that differ from those substances already discovered in tropical rain forest plants."
So the reason why "if the propical rain forests are not preserved, important types of medicine will never be developed. "