Q24 - Most land-dwelling vertebrates

[mymansupa]

Hi, can you please explain why E is correct. Is it because the answer is very broad and not very specific? Thank you...

[cyruswhittaker]

I think that's a good way to use elimination to get rid of some of the choices that are wrong.

(E) is correct because, like you mentioned, it is wholly consistent with the passage. The other choices, particularly A, B, C, D have go beyond the text.

Afterall, only a SINGLE example is provided.

Choice E is supported. The anatomical characteristics is in reference to the rotating limbs, the "some aquatic animals" is in reference to the Acanthostega, and the "represent an advantage" part is supported by sentence one: "characteristic useful for land movement."

[mymansupa]

Thanks... this explaination helped me understand the answer to PT 27, S1 #19 about the bueraucratically controlled orgs. It's weird because I def. have to train myself to see that some answers may be easy to spot and NOT talk myself out of picking them and talk myself into picking an answer that is complex. One word really determines the scope and strength of these answers. Thanks again...

[mturner]

I'm still a little confused with the explanation. With respect to answer E: "Certain anatomical characteristics common to some aquatic animals represent an advantage for survival on land", what is the characteristic common to aquatic animals that would be an advantage for land survival. I selected this answer simply because it was the last one standing, but your answer didn't seem clear.

Please clarify.

Thanks!

[cyruswhittaker]

Clarification on choice (E):

"Some" means one or more. The stimulus says that the Acanth, which was aquatic, also had rotating limbs, and sentence one states that these rotating limbs are a characteristic useful for land movement. Combining those statements leads us to infer choice (E).

[mturner]

Man o man! That illustrates perfectly how reading carefully AND understanding how some words are used is critical for getting the right answer. After reading over your explanation, I read over the stimulus and your definition of "some" and the answer made perfect sense.

Thanks for the help on this one. That's what so frustrating about this test. They make it so much harder than it really is!

[cyruswhittaker]

Yes I agree; the details can definately be tricky. Glad it helped.

[irene122]

Could any one specify the definition of "certain" as previously defined "some"?
Thank you very much for help!

[ManhattanPrepLSAT1]

Could any one specify the definition of "certain" as previously defined "some"?
Thank you very much for help!

Suppose you were to say that, "certain basketball players scored over 50 points in at least one basketball game last season."

If you were attempting to convert this a notational scheme and needed a quantification, you'd be selecting from "some," "most," and "all." The claim would at best allow you to infer that "some" basketball players scored over 50 points in at least one basketball game last season.

So I guess another way of putting it would be that it's the process of quantifying "certain" that leads to "some."

Make sense?

[irene122]

so you mean certain = some, I got it, thanks!

[patrice.antoine]

I eliminated AC (E) on the basis of "characteristic useful for land movement = represent an advantage survival on land".

Stimulus was about land movement. (E) was about survival. Can any moderator help me understand how this is not a stretch or detail shift??

[AlisaS425]

This is an Inference question. First we need to understand what the stimulus's saying:
- most land-dwelling vertebrates have rotating limbs terminating in digits (rl).
- rl is useful for land movement
- Biologists thought rl evolved after they abandoned aquatic environments
- The author provides an evidence against the biologists. Acanthostega was an ancestor of all land vertebrates (so it was the ancestor of those land-dwelling vertebrates stated in the first sentence!). Acanthostega had rl, but its skeleton was too feeble for land movement (so the author seems to suggest that rl might have nothing to do with "land movement")
- Acanthostega also breathed using only internal gills, indicating that it was exclusively aquatic

Though this stimulus is full of scientific terms, we don't have to understand them in depth. Just browse through it and focus on eliminating the wrong answers.

(A) the "anatomical characteristics" = rl, but we don't know if rl would be bad for survival underwater. Eliminate.
(B) we know nothing about anatomical characteristics common to most "aquatic" animals. Eliminate.
(C) contradicts the stimulus. The stimulus says that Acanthostega was exclusely aquatic, so it's unlikely to originate as land-dwelling species. Eliminate.
(D) contradict the stimulus. Rl is useful for land movement.

Eliminating (A)(B)(C)(D) leaves us with only (E), which is supported by the stimulus. "certain anatomical characteristics" (=rotating limbs) common to "some aquatic animals" (=Acanthostega) (also note that "some" means "at least one") represent an advantage for survival on land (rotating limbs is useful for land movement). So (E) is correct.