Reading Comprehension

PT145 · S1 · P4 · Q20 Genetic Typos

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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.

Topic

The revival of Lamarckian evolutionary theory through new research on heredity in the immune system.

Framework

Old / New; Present Debate

Main Point

Edward J. Steele and his team are challenging the widely dismissed Lamarckian theory of evolution by proposing that a mechanism in the immune system could allow acquired traits to be inherited, although most biologists remain skeptical due to lack of direct evidence. ( — End of P1 gives the core new idea, while P4 presents ongoing skepticism and the debate.)

P1: Introduction to Lamarck and Steele's Revival

Lamarck, a French biologist, suggested in 1809 that organisms could inherit traits acquired during their lifetimes. While this idea has been mostly laughed off by modern biologists, Edward J. Steele is now trying to bring Lamarckism back, claiming he’s found supporting evidence in how our immune system works.

P2: The Immune System’s Mutating Genes

This paragraph lays out the mystery of how the immune system adapts so quickly to new threats—partly by certain cells mutating their genes at an unusually high rate, creating "typos" as the DNA is copied to RNA. This enables the immune system to experiment with defenses on the fly.

P3: Steele’s Lamarckian Hypothesis and Its Mechanism

Here we get the details of Steele’s theory: he proposes that altered RNA is turned back into DNA (a process called "reverse transcription"), and suggests that viruses could carry this altered DNA into reproductive cells—potentially passing acquired traits to offspring.

20.

Which one of the following most accurately states the main point of the passage?

  1. The long-derided Lamarckian theory that

    Too Strong: proven correct

    The author is still tentative about Steele's theory, choosing to end the passage with the view of biologists who are still very skeptical about it. The passage was not congratulating Steele on having successfully proven Lamark correct.

    1% picked this

  2. Correct

    Steele and his colleagues have

    Why this is right

    This sums up the New idea without getting too specific about the details about how it would work. But because the passage is frame around this broad Lamarkian question of, "Do organisms change in adapting to their environment (acquired characteristic) and then pass on to their offspring the new characteristic they've acquired?" The fact that this answer is couched in language of, "They claim to have found evidence" reflects the tentative, unresolved nature of this New scientific theory.

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

    77% picked this

  3. Although Steele and his colleagues

    Too Strong

    Too Strong: succeeded in showing Out of Scope: elsewhere in body Steele has not successfully shown that changes in the immune system can be passed on to offspring. They have postulated that maybe a virus could carry altered DNA from immune system into the reproductive cells and thus get passed on to offspring. The last paragraph begins, "Even if the process Steele describes is possible", which indicates we don't actually know yet whether the process is possible. The author is saying, "even if we find out they're correct that this could happen, does it ever happen?" Finally, the author is never complaining that Steele has only showed that immune system acquired traits can be passed, but he's failed to show that acquired traits in other parts of the body can be passed along. The main clause of an answer choice should be the author's main emphasis. Do we think the author would want her one sentence takeaway from this passage to be, It's unlikely that you can pass acquired traits from anywhere but the immune system?

    1% picked this

  4. In contrast to the standard

    Contradicted

    The fact that the claims of Steele rest on purely circumstantial evidence is not in contrast to the standard theory of evolution. In the second sentence of the final paragraph, the author indicates that "evolutionary mechanisms are never observed directly, so we must (always) make do with circumstantial", so the standard theory of evolution also rests on purely circumstantial evidence.

    20% picked this

  5. By showing that RNA can

    Too Strong: showing / removed Wrong Obstacle

    Steele didn't show that RNA can revert back into DNA. In the second sentence of the 3rd paragraph, it says "reverse transcription" has been observed frequently in other contexts. It's implying that scientific research, not Steele, has already shown this to be possible. This was not the main obstacle to believing Lamarckian notions of transferring acquired traits to your offspring. The main obstacle (the troublesome question for Lamarckians, in that next sentence) is whether altered DNA could be carried to the reproductive genes and replace the DNA that's there.

    1% picked this

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