Examkin

Question

Difficulty: HardSelect-in-Passage Question Analysis

Read the passage below:

For decades, marine biologists maintained that deep-sea hydrothermal vent ecosystems depended exclusively on chemosynthetic bacteria oxidizing hydrogen sulfide to produce organic matter. This paradigm was seemingly bolstered by early observations of vast tubeworm colonies thriving in immediate proximity to sulfide-rich vent plumes. However, recent isotopic tracing reveals that several endemic macrofaunal species incorporate significant amounts of organic carbon synthesized via methane oxidation rather than sulfur pathways. Rather than merely supplementing energy budgets, this methanotrophic pathway provides the majority of metabolic carbon for specific vent organisms during periods of fluctuating volcanic activity. Consequently, models that fail to account for dual-pathway energy capture substantially underestimate the metabolic resilience of benthic communities against subterranean geochemical shifts.

Which sentence in the passage introduces empirical evidence that directly refutes the long-held assumption regarding the primary chemical source of energy for deep-sea vent ecosystems?

  1. A
    For decades, marine biologists maintained that deep-sea hydrothermal vent ecosystems depended exclusively on chemosynthetic bacteria oxidizing hydrogen sulfide to produce organic matter.
  2. B
    This paradigm was seemingly bolstered by early observations of vast tubeworm colonies thriving in immediate proximity to sulfide-rich vent plumes.
  3. However, recent isotopic tracing reveals that several endemic macrofaunal species incorporate significant amounts of organic carbon synthesized via methane oxidation rather than sulfur pathways.Answer
  4. D
    Rather than merely supplementing energy budgets, this methanotrophic pathway provides the majority of metabolic carbon for specific vent organisms during periods of fluctuating volcanic activity.
  5. E
    Consequently, models that fail to account for dual-pathway energy capture substantially underestimate the metabolic resilience of benthic communities against subterranean geochemical shifts.

Answer

The sentence starting with 'However, recent isotopic tracing reveals that several endemic macrofaunal species incorporate significant amounts of organic carbon synthesized via methane oxidation rather than sulfur pathways.' is the correct choice.
The correct sentence explicitly cites 'recent isotopic tracing'—an empirical scientific methodology—and presents data showing that macrofaunal species utilize carbon from methane oxidation instead of sulfur pathways. This directly refutes the long-held assumption introduced in the first sentence that vent communities depended exclusively on hydrogen sulfide oxidation.

Step-by-Step Solution

1
Analyze the prompt requirement
Identified that the target sentence must do two things: introduce new empirical evidence (data/measurements) and directly contradict the traditional belief that hydrogen sulfide oxidation was the sole energy source.
Select-in-passage items require matching specific rhetorical functions and evidential roles within the text structure.
2
Evaluate the passage sentences structurally
Sentence 1 articulates the traditional belief. Sentence 2 describes evidence supporting that old belief. Sentence 3 introduces isotopic tracing (empirical technique) showing carbon from methane oxidation (refuting exclusivity of sulfur). Sentence 4 expands on the importance of the pathway. Sentence 5 draws a broader conclusion.
Dissecting rhetorical roles prevents selecting surrounding context or downstream implications.
3
Select the target sentence
Confirmed that the sentence beginning with 'However, recent isotopic tracing...' fulfills all criteria by bringing forth the refuting empirical findings.
The structural contrast marker 'However' combined with the mention of isotopic data pinpoints the precise entry of counter-evidence.

Key Concept

Identifying rhetorical function and empirical evidence placement in dense academic text
Estimated Time:2m 0s
Rate this question

Topics

Select-in-Passage Question Analysis

More questions from this topic