Reading comp PrepTest 145 · Section 1 · Question 26

Correct. Question Type:
Strengthen

Strategy Overview:
Review Steele's argument and identify information/evidence that would back up his claims

Answer Anticipation/Relevant Lines:
Much like Strengthen questions in LR, we should identify the conclusion and premises, then try to strengthen their connection.

Let's start with Steele's conclusion—Adapted elements of the immune system can be passed down to later generations—thus validating Lamarckian evolution (Lines 12-16).

What's this based on? Well, Steele "hypothesizes" that altered RNA is reverse transcribed into DNA (Lines 30-33), but he's never seen that himself. He believes that this occurs via a virus carrying altered DNA to reproductive cells (Lines 41-43), but that's "speculative" (Line 39). And he has discovered a distinct pattern of mutations in genes that control the immune system that he believes indicates they were inherited (Lines 49-55), but other biologists believe there is a "less radical explanation" (Lines 55-56).

In short, each piece of evidence that Steele cites is qualified in some way—either because he hasn't witnessed it directly or because there are other explanations for it. So let's find an answer that establishes one of these things that he hasn't directly witnessed can happen, or that rules out an alternative explanation for the pattern.

Answer Explanation:
(Lines 41-43) Steele puts forward a theory as to how altered DNA in the immune system could end up in reproductive cells and thus be able to be passed down. The Author asks "does it ever actually occur?" Well, according to this answer, it does—it's happened in lab experiments with mice. While this answer doesn't prove that it happens in humans with their immune adaptations, it does establish that the process Steele puts forward is possible, thus strengthening the argument that it happens a bit. That's enough to make this answer correct.

Key Takeaway:
Much like in LR, examples of something happening strengthen that it could happen in a related context. Here, the mice reproductive cells being altered with DNA from viruses suggested that the same might happen to pass on acquired immunity in humans.

Incorrect. (Lines 48-55) Steele's argument is that the patterns suggest the information is carried in the reproductive cells, not brain cells. If anything, finding the pattern in other parts of the body might suggest that this pattern has nothing to do with adapted features of the immune system and is just a part of the human genome!

Incorrect. (Lines 27-29) When discussing the function of the immune system, the Author suggests that this is the case for at least some immune cells. However, that argument wasn't a unique part of Steele's theory—it appears to be an accepted fact of immunology.

Incorrect. This answer doesn't establish that the evolution towards having a long neck was done by individuals adapting and then passing that trait on. As such, it's compatible with Lamarck's and Darwin's theories, and so it doesn't support either of them—let alone Steele's limited revival of Lamarck's theory!

Incorrect. (Lines 41-43) This is a very tempting answer, showing an example of a species passing on acquired immunities to the next generation. However, it notes an alternative means of doing so—not DNA, but rather via the yolk sacs. Since the mechanism is different here than in Steele's theory, this answer actually weakens it, suggesting there might be another mechanism at play in humans.