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Difficulty: MediumOverall Text Structure Analysis

For decades, oceanographers believed that deep-sea ecosystems relied entirely on organic matter sinking from the sunlit surface. However, the discovery of hydrothermal vents in 1977 challenged this paradigm by revealing thriving communities independent of sunlight. Rather than utilizing photosynthesis, bacteria near these vents perform chemosynthesis, converting toxic chemicals into energy. This process forms the foundation of a unique food web, supporting organisms like giant tube worms. Consequently, researchers have revised their understanding of life’s metabolic boundaries, demonstrating that geothermal energy can sustain complex ecosystems in absolute darkness.

Which choice best describes the overall structure of the text?

  1. A
    It presents a scientific theory, details the experimental methodology used to test it, lists the empirical results, and proposes a new line of research.
  2. B
    It describes the specific chemical reactions of chemosynthesis, compares them to photosynthesis, and argues that giant tube worms are the most significant organisms in deep-sea food webs.
  3. It outlines a long-held scientific assumption, describes a discovery that challenged it, explains the biological process behind that discovery, and states a consequence for scientific understanding.Answer
  4. D
    It recounts the history of the 1977 expedition to find hydrothermal vents, describes the technology used to locate them, and argues that deep-sea exploration should be prioritized over space exploration.

Answer

The text begins by outlining a long-held scientific assumption, describes a discovery that challenged it, explains the biological process behind that discovery, and states a consequence for scientific understanding.
The correct answer accurately outlines the rhetorical steps of the passage: it starts with a widespread scientific assumption (that deep-sea life relies on sunlit surface matter), introduces a discovery challenging that view (hydrothermal vents), explains the metabolic process (chemosynthesis) that enables this environment, and closes by noting how this has changed the scientific consensus regarding where life can exist.

Step-by-Step Solution

1
Analyze the first sentence of the passage to identify the starting point.
The text begins by explaining that oceanographers long assumed deep-sea ecosystems depended entirely on organic matter sinking from the surface, representing a long-held belief.
Identifying the opening focus helps establish the initial step in the text's overall structure.
2
Analyze the middle portion of the passage to trace the development of ideas.
The text introduces the 1977 discovery of hydrothermal vents, which challenged the initial assumption, and explains how bacteria near these vents use chemosynthesis rather than photosynthesis to support life.
This establishes the transition from the old belief to a new discovery and the explanation of its mechanisms.
3
Analyze the final sentence of the passage to determine how the text concludes.
The text concludes by stating that this discovery led researchers to revise their understanding of life's metabolic boundaries.
This identifies the final rhetorical move, indicating the broader consequence of the discovery.

Key Concept

Overall Text Structure Analysis
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Overall Text Structure Analysis

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