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Question

Difficulty: MediumSentence Addition and Deletion Decisions

[1] In 1977, oceanographers aboard the research submersible *Alvin* made a startling discovery at the bottom of the Pacific Ocean: deep-sea hydrothermal vents spewing superheated, mineral-rich water. [2] Prior to this mission, scientists believed that all marine life depended, directly or indirectly, on sunlight for energy. [3] Yet, around these pitch-black vents, researchers found thriving ecosystems teeming with giant tube worms, ghost-white crabs, and unique species of clams. [4] These organisms did not rely on photosynthesis; instead, they survived on energy generated by chemosynthetic bacteria that converted toxic hydrogen sulfide from the vents into organic matter. [5] This discovery challenged the long-held scientific assumption that light was the sole foundation of all life on Earth.

The writer is considering deleting Sentence 4 from the passage. Should the sentence be kept or deleted?

  1. Kept, because it explains the specific chemical process that enables the vent-dwelling organisms to survive without sunlight.Answer
  2. B
    Kept, because it details how the scientists on the submersible Alvin collected samples of the chemosynthetic bacteria.
  3. C
    Deleted, because it introduces technical details about hydrogen sulfide that deviate from the paragraph's focus on deep-sea exploration.
  4. D
    Deleted, because it repeats information about photosynthesis that is already established in Sentence 2.

Answer

The sentence should be kept because it explains the specific chemical process that enables the vent-dwelling organisms to survive without sunlight.
The sentence should be kept because it provides the essential explanation of how the organisms in the vent ecosystems survive without sunlight, detailing the role of chemosynthetic bacteria in converting hydrogen sulfide to organic matter. This information directly supports the passage's main idea about the discovery of life forms independent of solar energy.

Step-by-Step Solution

1
Analyze the context of the paragraph and the role of Sentence 4.
The paragraph describes the 1977 discovery of deep-sea hydrothermal vents and the thriving ecosystems around them that exist without sunlight. Sentence 4 explains that these organisms survive via chemosynthetic bacteria converting hydrogen sulfide.
Understanding the function of the sentence in relation to the main idea is necessary to evaluate if it should be added, kept, or deleted.
2
Evaluate the impact of deleting Sentence 4.
Deleting Sentence 4 would remove the explanation of how these organisms survive in a pitch-black environment, leaving a logical gap between the description of the thriving ecosystem in Sentence 3 and the significance of the discovery in Sentence 5.
This helps determine whether the sentence is essential to the coherence and unity of the passage.
3
Select the option that correctly justifies keeping the sentence.
The option stating that the sentence should be kept because it explains the specific chemical process that enables the organisms to survive without sunlight is the only accurate choice.
This matches the pedagogical function of the sentence without mischaracterizing its content or the passage's focus.

Key Concept

Sentence Addition and Deletion Decisions
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Topics

Sentence Addition and Deletion Decisions

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