Q15

[geverett]

This question gave me a very hard time. I got it right, but it was a bare knuckle fight between D and E. Here are my thoughts:

(A) This is too narrow, and it's also not what the passage says. The last paragraph of the passage talks about a long standing assumption where parasitic interactions eventually evolve towards symbiosis. We can infer from this that the old assumption holds they can also be symbiotic. So answer choice A doesn't even address what the final paragraph is actually saying.
(B) Check out lines 38 - 44. It seems to refute this answer choice by suggesting they are not necessarily a distinct species.
(C) They are actually closely related to fungus not algae.
(D) This is right. I chose it during timed and untimed practice before checking my answers. It's not ideal. I really wanted this answer choice to have additional info on the implications of the research mentioned in the final paragraphs. It didn't have that info. It's questions like this that make me roll my eyes at the LSAT. =)
(E) "By means of their common evolutionary origins" is why I got rid of this. The explanation is revealed by the new DNA study that has been conducted, and the common evolutionary origins are also revealed from the DNA research.

[maryadkins]

Nice thinking! Couple of additional comments:

(B) The term "species" is not mentioned in the passage at all. So red flag there, right? Regardless, you're right that this is absolutely not what the passage is saying. Lichen is in the fungus family tree.
(E) We know based on the DNA research that lichen is in the fungus family tree, but just to your comment--we still don't know that they have a common evolutionary origin. It seems more like fungus had an origin then lichen emerged as a sub-group of fungus. (This isn't a critical point though.)

[geverett]

Some really great stuff here Mary. I'm interested to hear your thoughts a bit more on E.

(B) The word species is used in line 36. Check out lines 32 - 38 to throw it in context.
(E) You are right. There is no mention of a "common evolutionary origin" Fungus is the umbrella family tree, and lichens fall under that family tree.

[nflamel69]

here are some of my thoughts for E:

first of all, the passage is about lichen-forming fungi. So a red flag would be the discussion of similarities between lichen and fungi.

secondly, the visible similarities is in fact talked about in 1st paragraph and is in last sentence. I think it is deliberately to trick people who think the Main point will be in last sentence. But if you read closely, the visual similarities is just one side implication of the general idea that uncovered relationship of these lichen forming fungi.

What do you think geeks?

[Djjustin818]

I was actually choosing between A and D. I chose A (wrong answer) because the answer states:

"New research suggests that fungi are not only parasitic but aso symbiotic organisms"

Lines 55-59 state,
"Given the new layout of the fungus family tree resulting from the lichen study, it appears that fungi can evolve toward mutualism and then just as easily turn back again toward parasitism"

I inferred that because the new research uncovered their relationship to the fungus family tree (D), then the research suggests the fungi are not only parasitic but also symbiotic (A). In other words, I thought that answer D concluded answer A, which is why I chose A.

Could someone explain why my thought process is wrong please?

[ManhattanPrepLSAT1]

Good question, but the passage stated that the new research did help overturn the longstanding assumption that long-term parasitic interactions inevitably evolve over time to a greater benignity (lines 45-49), but the passage stated that the researchers already knew that funghi are usually parasitic or symbiotic (line 16). The beginning of the 2nd paragraph discusses why the new research was so difficult to obtain, suggesting that the information presented there was known before the researchers overcame the challenge and so is not part of the new research.

Hope that helps!

[Yu440]

Hello, I was also torn between D and E. I decided to eliminate E on the basis that explaining the visible similarities between lichens and fungi isn't a main point of the passage. It is just a by-product of the DNA research. Is this understanding correct? Thanks!

[ohthatpatrick]

Yes, that's correct.

On science passages, most of them have a Old vs. New structure. We need to understand, "What was the Old, what is the New, how does the author feel about the New?"

OLD - evolutionary origins of lichen-forming fungi have been a mystery

NEW - a recent DNA study has revealed the relationship of lichen-forming fungi to several previously known branches of the fungus family tree

AUTHOR - one implication is that this shows that evolution does not always go from parasitism towards mutualism