Self-study
P1
The French biologist Jean-Baptiste de Lamarck (1744–1829) outlined a theory of evolutionary change in 1809, 50 years before Darwin's . ██ ███ ██████ ██ ████████ █████████ █████ ████ ███ ████ █████████ ██████ ██ ████████ ██ █████ ███████████ ███ ████ ████ ██ ██ █████ █████████ ███ ███ ███████████████ ████ ████ █████████ ███
Lamarck's Theory of Evolution ·
Environmental adaptations could be inherited
Critique ·
Consensus view among scientists is that Lamarck is wrong
Steele ·
Claims to have evidence for Lamarckism
Steele claims to have found evidence for Lamarckian hereditary mechanism in the immune system. Not sure what this means but presumably the rest of the passage will flesh this out.
P2
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Phenomenon ·
Complexity of the immune system
How does our immune system work? If knowledge of how to defend against attacks are coded in the genes, how does it defend against a new disease, something it's never encountered before?
Partial Explanation ·
Some immune system cells mutate a lot
The immune system doesn't know. But "typo" mutations (when an error occurs when transcribing DNA into RNA) happen a lot which allows immune system to test different defenses.
P3
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Steele's Hypothesis ·
Supporting Lamarckism
Steele hypothesizes that the "typo" mutations that end up working gets coded back into the immune cell's DNA. Steele further hypothesizes that a virus then carries the altered immune cell DNA into the DNA of the reproductive cells. That's the mechanism by which an environmentally induced adaptation (in the immune cell) gets inherited.
P4
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Evidence ·
for Steele's Hypothesis?
Steele ·
Yes, circumstantial evidence
Steele claims that there's circumstantial evidence. Something about a pattern of mutations. Not sure what this means.
Other Biologists ·
No, there are simpler explanations for the "pattern of mutations"
Passage Style
Critique or debate
Phenomenon-hypothesis (RC)
21.
The author most likely calls █ ███████ ████ ██ ████████ █
a
distinguish it from █████████ ████ ███ ████████
The author doesn’t distinguish between adaptive (helpful) mutations and unhelpful mutations in P2. The author uses “typo” as part of a description of how mutations occur. But she doesn’t go into the difference between adaptive mutations an unhelpful mutations, so (A) can’t be the purpose of “typo.”
b
characterize it as ██████████ ███████████████
The author uses “typo” as part of a description of how mutations occur. This is part of the context for understanding how Steele’s hypothesis works. There’s no indication the author believes the mutations described in connection with “typo” are inconsequential (unimportant).
c
indicate that it ██ ██ ████████ ██ █████████ ███████
This best captures the purpose of “typo.” In the same way that one might make a small mistake when typing something out on a computer, there can be a small mistake when DNA is copied into RNA. This small mistake is a mutation.
d
emphasize that it ██ ██████ ██████████
The author doesn’t discuss or mention the potential difficulty of noticing mutations. So it wouldn’t make sense for the use of “typo” to indicate that something is easily overlooked. The issue of overlooking a mutation that has occurred isn’t relevant to P2.
e
suggest an analogy ███████ ██████████ █████████████ ███ ███████ ████████
The author uses the word “typo” to help us understand how a mutation might occur when transcribing from DNA to RNA. This word does involve the context of text and writing, but this doesn’t imply that the author wants to analogize the broad concept of scientific investigation to textual analysis. We’re simply discussing mutations and how they occur.