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Difficulty: MediumSelect-in-Passage Question Analysis

Read the passage below:

[1] For decades, marine biologists assumed that abyssal benthic ecosystems relied entirely on organic carbon sinking from photic surface waters. [2] However, the discovery of hydrothermal vent communities along mid-ocean ridges forced a fundamental reassessment of deep-sea bioenergetics. [3] At these hydrothermal vents, chemosynthetic bacteria utilize dissolved hydrogen sulfide issuing from subterranean fissures as an electron donor to fix inorganic carbon into cellular biomass. [4] This localized biological productivity establishes an autonomous food web independent of solar energy, sustaining dense populations of specialized fauna such as giant tube worms and vent shrimp. [5] Consequently, astrobiologists now treat subterranean chemosynthesis as a primary analog when evaluating the habitability of subsurface oceans on icy moons like Europa and Enceladus.

Which sentence in the passage identifies the specific chemical process by which primary energy is generated at deep-sea hydrothermal vents?

  1. A
    For decades, marine biologists assumed that abyssal benthic ecosystems relied entirely on organic carbon sinking from photic surface waters.
  2. B
    However, the discovery of hydrothermal vent communities along mid-ocean ridges forced a fundamental reassessment of deep-sea bioenergetics.
  3. At these hydrothermal vents, chemosynthetic bacteria utilize dissolved hydrogen sulfide issuing from subterranean fissures as an electron donor to fix inorganic carbon into cellular biomass.Answer
  4. D
    This localized biological productivity establishes an autonomous food web independent of solar energy, sustaining dense populations of specialized fauna such as giant tube worms and vent shrimp.
  5. E
    Consequently, astrobiologists now treat subterranean chemosynthesis as a primary analog when evaluating the habitability of subsurface oceans on icy moons like Europa and Enceladus.

Answer

The sentence stating that chemosynthetic bacteria utilize dissolved hydrogen sulfide issuing from subterranean fissures as an electron donor to fix inorganic carbon into cellular biomass.
The sentence stating that chemosynthetic bacteria use dissolved hydrogen sulfide as an electron donor to fix inorganic carbon into cellular biomass explicitly describes the biochemical pathway and energy generation process at hydrothermal vents requested by the prompt.

Step-by-Step Solution

1
Analyze the prompt requirement
The target sentence must explicitly detail the chemical process producing primary energy/biomass at hydrothermal vents.
Select-in-passage questions require matching the prompt's specific functional criteria to a single sentence's content.
2
Evaluate each sentence's rhetorical role
Sentence [1] gives past background; Sentence [2] states the paradigm shift; Sentence [3] details chemical oxidation of hydrogen sulfide to fix carbon; Sentence [4] describes ecological food web consequences; Sentence [5] extends findings to astrobiology.
Distinguishing between background context, mechanism, outcome, and broader implications isolates the requested evidence.
3
Confirm the exact match
Sentence [3] is the only sentence explaining the biochemical oxidation reaction (using hydrogen sulfide as an electron donor to fix carbon).
Sentence [3] directly answers 'how' primary energy is generated at the chemical level.

Key Concept

Identifying specific factual evidence and rhetorical function within a passage (Select-in-Passage)
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Select-in-Passage Question Analysis

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