Reading ComprehensionDifficulty: Hard

PT145 S1 P4 Q25 Explanation

Genetic Typos

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsAuthor OpinionScience

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Passage

The French biologist Jean-Baptiste de Lamarck (1744–1829) outlined a theory of evolutionary change in 1809, 50 years before Darwin’s On the Origin of Species. Lamarck’s basic idea was that organisms change in adapting to their environment and then pass on to their offspring the new characteristics they have acquired. Since then, Lamarck his colleagues claim to have found evidence for a Lamarckian hereditary mechanism in the immune system.

The immune system is an evolutionary puzzle in its own right: How is it that our bodies can quickly respond to so many different kinds of attacks? Is all this information in the genes? If so, then how does our immune system defend against new diseases? Part of the answer comes from the immune system to test out different defenses until it finds one that does the job.

Steele hypothesizes that the altered RNA then reverts back into DNA. Indeed, such “reverse transcription” of RNA back into DNA has been observed frequently in other contexts. But the troublesome question for Lamarckians is this: Could this new DNA then be carried to the reproductive genes (in the sperm and egg cells), could carry the altered DNA to the reproductive cells and replace the DNA in those cells.

But even if the process Steele and his colleagues describe is possible, does it ever actually occur? Evolutionary mechanisms are never observed directly, so we must make do with circumstantial evidence. Steele and his colleagues claim to have found such evidence, namely a “signature” of past events that is “written all over” suggest there may be other, less radical explanations for the pattern of mutations that Steele cites.

What this question is testing

Author Opinion

Your task

Pin down exactly what the question asks about the passage — a detail, the author's view, the structure, or the main point — before looking at the choices.

Common trap

Answers that restate a true detail from the passage but don't answer the specific question being asked.

Winning move

Anticipate the answer in your own words from the passage, then find the choice that matches that prediction.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
25.

The passage most strongly suggests that the author would agree with which one of

Answer choices

  1. Too Strong: probably can be passed3% picked this

    Contrary to the opinion of most modern biologists, certain acquired characteristics probably can be passed on from one

    The author isn't this far in favor of Steele that she'd be ready to say, "Okay, I'm basically convinced. Some acquired traits probably do get passed from one generation to the next". The last couple paragraphs are saying, "We know that mutated RNA can reverse transcribe back into modified DNA (so experience does have the power to change your DNA), but we're not sure if that modified DNA can actually make it into the reproductive cells and thus be passed on. Steele thinks a virus can do it, but biologists are not convinced by that yet."

  2. Correct58% picked this

    Steele and his colleagues have not actually observed the process of reverse transcription

    Why this is right

    This is supported by the first two sentences of the 3rd paragraph: Steele hypothesizes that the altered RNA then reverts back into DNA. If Steele and colleagues had actually observed this reverse transcription, then there would be no need to use the verb 'hypothesizes', which sort of means 'guesses'. Indeed, such "reverse transcription" of RNA back into DNA has been observed frequently in other contexts. What are these other contexts where reverse transcription has been observed? They must be other than in the context of the immune system, since the immune system is what we were talking about throughout paragraph 2. The combination of "we've seen this elsewhere" with "Steele hypothesizes that this is going on in the immune system" suggests that Steele has not directly observed this happening in immune cells.

    Skill tested: Author Opinion · how this choice captures the passage's function is the move to repeat next time.

  3. Wrong Point of View4% picked this

    The patterns of mutations concentrated in particular areas of genes that carry instructions for immune system responses indicate that the DNA in these genes

    This is Steele and colleagues' point of view in the final paragraph. The author does not seem to be fully on board with this interpretation yet. We can surmise this because of how the final paragraph is organized. 1. The author skeptically asks, "but does this ever happen in real life?" 2. Steele & Co. claim to have found evidence. They claim that a pattern of mutations blah blah blah. 3. Other biologists are not swayed. They suggest there may be less radical explanations. The author is willing to concede the possibility that Steele is correct, but she still finds his interpretation of these patterns of mutations to be a pretty radical one, and she gives the final word to biologists who are skeptical of it, so she is choosing to leave us with that very ambivalent feeling.

  4. Too Strong: probably confined10% picked this

    The passing on of acquired characteristics from one generation to the next, if it occurs at all, is probably

    We can't really put our finger on any point in the passage where the author is saying, "If there is any passing on of acquired characteristics, then it's probably only found in the immune system." Just because this passage, which spotlights the work of an immunologist (Steele), only talks about acquired characteristics being passed on within the immune system doesn't mean that our author thinks, "Were there to be acquired traits passed on, they would probably only be relating to the immune system".

  5. Opposite, if anything24% picked this

    Unless a hypothesis can be confirmed by direct observation, it should be regarded as speculation

    The second sentence of the final paragraph seems to make an allowance for the fact that when it comes to the science of evolutionary theory, we never observe it directly: we must make do with circumstantial evidence The author is not mad that Steele only has circumstantial evidence. She is saying, "yes, that's to be expected of evolutionary science". If this answer were what the author believed, then she would consider evolutionary theory to be speculation, not science, and that is a very radical view to attribute to any scientific thinker.

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