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Question

Difficulty: MediumSelecting Concluding Sentences and Transitions

Passage Segment:

In 1977, oceanographers aboard the research submersible *Alvin* made a startling discovery on the Pacific ocean floor: hydrothermal vents spewing mineral-rich water into the pitch-black depths. Rather than finding a barren wasteland, the scientists observed a thriving ecosystem teeming with giant tube worms and ghost-white crabs. This discovery revolutionized our understanding of biology, demonstrating that entire communities could flourish without a single ray of sunlight. [1] **Furthermore, the *Alvin* submersible had been upgraded recently with titanium hulls to withstand extreme pressure.**

Instead of utilizing photosynthesis, the organisms surrounding these vents rely on chemosynthesis, a process where bacteria convert dissolved hydrogen sulfide gas into organic matter. This geothermal energy pathway suggested that life on Earth might have originated in the deep sea rather than in shallow, sunlit waters.

Question:

Which choice most effectively concludes the first paragraph and provides a transition to the second paragraph?

  1. A
    NO CHANGE
  2. Indeed, these deep-sea communities did not depend on solar energy at all.Answer
  3. C
    Consequently, these creatures do not require solar energy, they thrive on alternative forms of power.
  4. D
    On the contrary, the unique organisms, that live near the vents, do not depend on the sun.

Answer

Indeed, these deep-sea communities did not depend on solar energy at all.
The correct choice most effectively concludes the first paragraph and transitions to the second. The first paragraph discusses a thriving ecosystem that exists without sunlight. The second paragraph explains that instead of using photosynthesis, these organisms rely on chemosynthesis. The statement emphasizing that these deep-sea communities do not depend on solar energy at all wraps up the idea of thriving without sunlight and directly introduces the contrast with photosynthesis/chemosynthesis in the next paragraph.

Step-by-Step Solution

1
Analyze the context of the two paragraphs
The first paragraph discusses a thriving deep-sea ecosystem that exists without sunlight. The second paragraph explains that these organisms use chemosynthesis instead of photosynthesis.
Understanding the surrounding context is necessary to determine the logical bridge between the paragraphs.
2
Identify the transition required
The transition needs to connect the idea of flourishing without sunlight to the chemical process of chemosynthesis described in the next sentence.
An effective transition must logically link the preceding and succeeding ideas.
3
Evaluate the choices for grammatical and structural correctness
Identify that the choice stating these communities did not depend on solar energy at all is grammatically correct and provides the most logical bridge.
Eliminating options with grammatical errors (such as comma splices and incorrect restrictive commas) narrows down the choices to the stylistically and logically superior option.

Key Concept

Selecting Concluding Sentences and Transitions
Estimated Time:1m 0s
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Topics

Selecting Concluding Sentences and Transitions

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