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Difficulty: EasyOverall Text Structure Analysis

Deep-sea hydrothermal vents present an exceptionally harsh environment for marine life, characterized by extreme temperatures and toxic chemical concentrations. For decades, biologists struggled to understand how specialized organisms like tube worms could survive without access to sunlight for photosynthesis. Researchers eventually discovered that these organisms rely on a process called chemosynthesis. In this process, symbiotic bacteria living inside the tube worms convert the hydrothermal fluids' hydrogen sulfide into usable energy. This symbiotic relationship allows entire ecosystems to thrive in the dark ocean depths, successfully resolving the mystery of their survival.

Which choice best describes the overall structure of the text?

  1. It describes a harsh environmental condition, presents a biological question that puzzled scientists, and explains how a scientific discovery answered that question.Answer
  2. B
    It contrasts two competing scientific theories about deep-sea survival and argues that one theory is superior to the other.
  3. C
    It details the chemical properties of hydrogen sulfide and focuses on how bacteria utilize this compound in different deep-sea environments.
  4. D
    It describes a proposal to introduce new bacterial species to hydrothermal vents and lists the ecological benefits of doing so.

Answer

The choice stating that the text describes a harsh environmental condition, presents a biological question that puzzled scientists, and explains how a scientific discovery answered that question is correct.
The correct answer accurately outlines the progression of the passage. The text first establishes the harsh environmental conditions of hydrothermal vents, then introduces the mystery regarding how organisms survive there without sunlight, and finally explains the discovery of chemosynthesis as the biological explanation that answers the mystery.

Step-by-Step Solution

1
Analyze the beginning of the passage to identify the initial topic.
The text begins by introducing the extreme, toxic environment of deep-sea hydrothermal vents and notes that biologists struggled to explain how organisms survive there without sunlight.
This establishes the context and the biological puzzle that initiates the text's structure.
2
Analyze the middle and end of the passage to identify the transition and conclusion.
The text transitions to discussing the discovery of chemosynthesis, explaining how bacteria convert chemical compounds to energy to resolve the mystery of survival.
This shows how the passage moves from presenting a problem to explaining its scientific solution.
3
Match the sequence of moves to the answer choices.
The sequence of 'harsh environment' to 'unanswered question' to 'scientific discovery explaining survival' matches the correct choice.
Matching the rhetorical moves confirms the overall structure of the passage.

Key Concept

Overall Text Structure Analysis
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Topics

Overall Text Structure Analysis

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