Central Ideas and Details Flashcards

Read the following passage: 'The monarch butterfly's annual migration spans thousands of miles, from Canada to central Mexico. Scientists have long marveled at how these insects navigate with such precision despite having brains the size of a pinhead. Recent research suggests they use a time-compensated sun compass, integrating light cues with their internal circadian clock.' What is the central idea of this passage?

Answer: Monarch butterflies possess a remarkable navigation system that scientists are still studying

The passage focuses on the surprising navigational ability of monarch butterflies and ongoing scientific investigation, not merely the migration route or a single finding.

Read the following passage: 'Urban heat islands occur when cities replace natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat. This effect can raise urban temperatures by 1–7°F compared to surrounding rural areas. The consequences include increased energy consumption, elevated emissions, and compromised human health and comfort.' Which statement best summarizes the author's central claim?

Answer: Urban heat islands are caused by natural land being replaced by heat-retaining surfaces, with significant negative consequences

The passage defines urban heat islands, explains their cause (replacing natural land), and lists multiple consequences — all captured in choice B.

A passage states: 'The printing press, invented by Johannes Gutenberg around 1440, democratized knowledge by making books affordable and widely available. Before this invention, manuscripts were hand-copied by monks, limiting literacy to the elite. Within decades of the press's introduction, book production soared and literacy rates began climbing across Europe.' What detail best supports the central idea that the printing press expanded access to knowledge?

Answer: Book production soared and literacy rates climbed after the press was introduced

The rise in book production and literacy rates directly supports the claim that knowledge became more accessible after the printing press.

Read this passage: 'Coral reefs cover less than one percent of the ocean floor but support approximately 25 percent of all marine species. They provide food and livelihoods for hundreds of millions of people and protect coastlines from storm damage. Despite their importance, reefs are threatened by warming oceans, ocean acidification, and pollution.' What is the main idea?

Answer: Coral reefs are extraordinarily valuable ecosystems that face serious threats

The passage establishes both the enormous value of coral reefs and the threats they face — choice B captures both aspects.

A student reads: 'Sleep deprivation impairs cognitive function in ways that mirror alcohol intoxication. After 17–19 hours without sleep, performance on tests resembles that of someone with a blood alcohol level of 0.05%. After 24 hours awake, impairment equals a blood alcohol level of 0.10%, which is above the legal driving limit in most countries.' What supporting detail reinforces the central claim that sleep deprivation seriously impairs cognition?

Answer: After 24 hours awake, impairment equals illegal intoxication levels

The comparison to exceeding legal blood alcohol limits is a concrete detail that reinforces how severely sleep loss impairs cognitive function.

Read this passage: 'The Amazon rainforest produces about 20 percent of Earth's oxygen through photosynthesis. It also regulates regional and global climate by releasing vast amounts of water vapor. Home to an estimated 10 percent of all species on Earth, it represents an irreplaceable reservoir of biodiversity.' The primary purpose of listing these three facts is to:

Answer: Demonstrate the Amazon's critical and multifaceted importance to the planet

The three facts about oxygen, climate regulation, and biodiversity collectively build the case for the Amazon's enormous global value.

A passage reads: 'In 1962, Rachel Carson published Silent Spring, documenting the harmful effects of pesticides on wildlife, particularly birds. The book sparked public outrage and led directly to a nationwide ban on DDT in the United States. It is widely credited with launching the modern environmental movement.' What is the central idea?

Answer: Silent Spring had a transformative impact on environmental policy and public consciousness

The passage traces the book's publication to its policy impact and broader movement-launching effect, centering on the book's transformative influence.

Read this: 'Ancient Greek city-states, or poleis, were independent political units, each with its own government, laws, and often its own currency. While they shared language and religion, their political rivalries were fierce. Athens and Sparta, for example, fought a devastating 27-year war that weakened all of Greece.' What detail best supports the claim that Greek city-states were politically divided despite cultural unity?

Answer: Athens and Sparta fought a 27-year war that devastated Greece

A 27-year devastating war between two prominent city-states is the strongest concrete evidence of political division despite cultural commonality.