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Difficulty: MediumSelect-in-Passage Question Analysis

Read the passage below:

For decades, evolutionary biologists maintained that phenotypic modifications induced by environmental stressors were strictly non-heritable, operating entirely outside the framework of Darwinian natural selection. Recent investigations into Arabidopsis thaliana, however, demonstrate that exposure to persistent insect herbivory triggers specific DNA methylation patterns that alter defense-gene expression in subsequent, unexposed generations. Proponents of transgenerational epigenetic inheritance contend that these biochemical alterations represent an adaptive mechanism enabling offspring to pre-emptively calibrate their physiological defenses against recurrent ecological threats. Skeptics counter that such epigenetic marks decay rapidly over two or three generations, arguing that their transient nature precludes them from serving as a substrate for long-term evolutionary change. Nevertheless, empirical models confirm that even short-lived epigenetic adaptations can significantly alter population dynamics during acute ecological shifts, bridging the gap between immediate acclimation and permanent genetic adaptation.

Which sentence in the passage presents empirical evidence that directly challenges the traditional view regarding the non-heritability of environmentally induced traits?

  1. A
    For decades, evolutionary biologists maintained that phenotypic modifications induced by environmental stressors were strictly non-heritable, operating entirely outside the framework of Darwinian natural selection.
  2. Recent investigations into Arabidopsis thaliana, however, demonstrate that exposure to persistent insect herbivory triggers specific DNA methylation patterns that alter defense-gene expression in subsequent, unexposed generations.Answer
  3. C
    Proponents of transgenerational epigenetic inheritance contend that these biochemical alterations represent an adaptive mechanism enabling offspring to pre-emptively calibrate their physiological defenses against recurrent ecological threats.
  4. D
    Skeptics counter that such epigenetic marks decay rapidly over two or three generations, arguing that their transient nature precludes them from serving as a substrate for long-term evolutionary change.
  5. E
    Nevertheless, empirical models confirm that even short-lived epigenetic adaptations can significantly alter population dynamics during acute ecological shifts, bridging the gap between immediate acclimation and permanent genetic adaptation.

Answer

The sentence starting with 'Recent investigations into Arabidopsis thaliana...' is the correct choice because it provides the specific empirical data (DNA methylation altering defense-gene expression across unexposed generations) that refutes the baseline assumption of non-heritability.
The correct response is the sentence reporting the research on Arabidopsis thaliana. It directly presents empirical data—specifically that insect herbivory triggers transgenerational DNA methylation patterns—which demonstrates that environmentally induced traits can indeed be inherited, directly refuting the traditional view introduced in the opening sentence.

Step-by-Step Solution

1
Analyze the prompt requirement
The target sentence must fulfill two criteria: (1) state empirical evidence/data, and (2) directly challenge the traditional view that environmentally induced traits cannot be inherited.
Select-in-passage items require mapping rhetorical function precisely to sentence content.
2
Evaluate candidate sentences against rhetorical roles
The first sentence sets up the baseline assumption (non-heritability). The second sentence introduces experimental findings on Arabidopsis thaliana showing inherited methylation patterns.
Identifying the pivot word 'however' signals a shift from traditional belief to counter-evidence.
3
Confirm target sentence boundaries and scope
The second sentence contains the specific observational evidence (exposure to herbivory causing inherited methylation patterns), satisfying both prompt conditions.
Subsequent sentences present theoretical claims, counter-objections, and broader implications rather than the core empirical finding.

Key Concept

Identifying Empirical Evidence versus Theoretical Interpretation in Reading Comprehension
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Topics

Select-in-Passage Question Analysis

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