Central Idea Practice Test

Read the passage, then answer: What is the central idea of the passage?

In 1928, Alexander Fleming returns to his laboratory after a brief holiday and notices something that looks, at first glance, like a failure. A dish of bacteria has been contaminated by a stray mold, and the colonies nearest the intruder appear strangely thinned, as if an invisible boundary has been drawn. Many researchers might discard the plate, since contamination usually ruins careful work, but Fleming pauses long enough to ask why the bacteria retreat.

He tests the mold’s effect by transferring it to fresh cultures, and the same clearing appears, repeating with a consistency that suggests a chemical agent rather than mere coincidence. Fleming concludes that the mold releases a substance capable of inhibiting bacterial growth, and he names it penicillin after the mold genus, Penicillium. However, he also recognizes a practical obstacle, because the substance is unstable and difficult to purify with the tools available to him.

For years, penicillin remains more promise than medicine, not because the idea is flawed, but because the engineering is unfinished. In the early 1940s, Howard Florey and Ernst Chain, working with a larger team, develop methods to concentrate and produce penicillin in usable quantities. Their work turns Fleming’s observation into a treatment that can be tested, refined, and distributed, especially when wartime injuries make infection a widespread threat.

The story is often told as a tale of luck, yet the deeper lesson is that discovery depends on attention and persistence. An accident provides the initial clue, but careful questioning, repeated experiments, and later collaboration convert that clue into a tool that saves lives.

Read the passage, then answer: Which statement best describes the passage's central message?

When Mary Shelley writes Frankenstein, she does not simply invent a frightening creature and then chase readers through dark corridors. Instead, she builds a narrative in which ambition, once detached from responsibility, becomes a form of blindness. Victor Frankenstein is not portrayed as a villain who delights in harm, but as a young scholar who confuses intellectual achievement with moral permission. Because he treats creation as a private triumph, he refuses the ordinary obligations that follow any act of making.

The novel’s structure reinforces this theme through layered storytelling, since Victor’s account is framed by Walton’s letters, and the creature later speaks for himself. Each narrator believes he is reasonable, yet each reveals how easily self-justification masquerades as truth. Walton, hungry for glory, admires Victor as a warning he does not fully heed, while Victor insists that his intentions excuse the consequences he cannot manage.

The creature’s education deepens the moral problem rather than simplifying it. He learns language and empathy by observing a family from the shadows, and he recognizes that companionship is not a luxury but a need. Nevertheless, repeated rejection shapes his anger, and the violence that follows is presented as tragic escalation, not as innate monstrosity. Shelley thereby complicates the easy lesson that “the monster” is purely evil, because the creature’s suffering is tied to Victor’s abandonment.

By the end, the novel suggests that knowledge without accountability is unstable, and that creators remain bound to what they bring into the world. The terror arises less from the creature’s strength than from the human habit of fleeing responsibility once the applause fades.