ACT (Enhanced)ReadingMedium
Read the following excerpt from a science article: 'The recent discovery of extremophiles thriving in hydrothermal vents deep beneath the ocean's surface has challenged long-held assumptions about the conditions necessary for life. These organisms, which flourish in environments previously thought to be inimical to biological processes, utilize chemosynthesis rather than photosynthesis. Their existence suggests that life may be far more resilient and widespread throughout the universe than previously imagined.' Which of the following statements best summarizes the central idea of this excerpt?
- ALife in the universe is likely to be abundant due to chemosynthesis.
- BThe discovery of extremophiles expands our understanding of life's potential and prevalence.
- CHydrothermal vents are the only locations where extremophiles can survive.
- DExtremophiles use chemosynthesis, a process distinct from photosynthesis.
Show answer & explanationAnswer & explanation
Correct answer: B. The discovery of extremophiles expands our understanding of life's potential and prevalence.
The excerpt begins by stating that the discovery 'challenged long-held assumptions' and concludes by suggesting 'life may be far more resilient and widespread throughout the universe.' This overarching message about expanding understanding is the central idea.
Why the other options are wrong
- A. While implied, the abundance is a consequence of the expanded understanding, which is the broader central idea, not the sole focus on chemosynthesis.
- C. The excerpt states they thrive 'in hydrothermal vents,' but doesn't claim these are the *only* locations.
- D. This is a supporting detail explaining *how* extremophiles survive, not the main point about their significance.
Central Idea
The central idea (or main idea) is the most important point or message that the author wants to convey about the topic.
- It is often explicitly stated but can also be implied.
- It is distinct from supporting details.
- It typically answers the question 'What is this passage mostly about?'
Memory trick: Look for the main point, not just the details.