Question 5: Understanding Sentence Function

Which choice best describes the function of the underlined sentence in the text as a whole?

In the 1950s, scientists didn't know much about the ocean floor. Many scientists at the time believed that the ocean floor was mostly flat. But geologist Marie Tharp and her research partner, Bruce Heezen, proved that this idea was wrong. Using sonar data collected from the Atlantic Ocean, Tharp and Heezen showed that the floor was filled with canyons, mountains, and valleys.

• A) It identifies a scientific belief that Tharp and Heezen showed to be wrong.
• B) It describes the design of Tharp and Heezen's experiment.
• C) It emphasizes a disagreement between Tharp and Heezen.
• D) It presents data to support a claim that Tharp and Heezen made.

What's Required? The keyword here is "function." We need to figure out the *job* this sentence does in the paragraph. Why did the author include it?

The sentence highlights an old, common belief ("ocean floor was mostly flat"). The very next sentence starts with "But" and introduces Tharp and Heezen, who "proved that this idea was wrong". So, the underlined sentence sets up the outdated idea that the rest of the text corrects.

Correct Answer: (A)

• (B) is wrong because the experiment details ("Using sonar data...") come *after* the underlined sentence.
• (C) doesn't fit; the text shows Tharp and Heezen working together, not disagreeing.
• (D) is incorrect. The underlined sentence states a *belief*, not data supporting Tharp and Heezen's later claim.

Question 6: Understanding Phrase Function

Which choice best describes the function of the underlined phrase in the text as a whole?

In the early days of television in the 1940s, many people thought that US television programs would rely on the financial support of ad agencies and commercial sponsors, much like radio did. But advertisers hesitated to jump into a new space, particularly at a time when the manufacturing of new television sets was stalled due to the US's involvement in World War II. Broadcasters, like the National Broadcasting Company (NBC), needed to persuade advertisers to support their programming despite not knowing whether there would be a robust television audience to begin with.

• A) It compares the beginnings of radio programming with the beginnings of television programming in the United States.
• B) It identifies a specific reason behind some advertisers' hesitance to support television.
• C) It describes how broadcasters attempted to convince advertisers to support television.
• D) It explains why a type of television programming was popular at the time.

What's Required? Similar to Q5, but focusing on a *phrase*. Why is this specific detail included?

The text first mentions advertisers were hesitant ("hesitated to jump in"). The underlined phrase then immediately explains *why* they hesitated – specifically because TV set manufacturing was stalled due to WWII. It gives a direct cause for their reluctance.

Correct Answer: (B)

• (A) The comparison to radio happens *earlier* ("much like radio did"). This phrase doesn't make that comparison.
• (C) How broadcasters tried to convince advertisers ("needed to persuade advertisers") is discussed later; the underlined phrase isn't about their persuasion tactics.
• (D) The phrase explains advertiser hesitation, not the popularity of any specific programming.

Question 7: Identifying Main Purpose

Which choice best describes the main purpose of the text?

Pteropods are small swimming snails with thin, delicate calcium carbonate shells. These animals are thought to be especially vulnerable to ocean acidification due to calcium carbonate's susceptibility to dissolution at lower pH values. Victoria L. Peck and colleagues recently found that the periostracum (a protective coating on pteropods' outer shells) prevents this dissolution when intact. Moreover, the team was surprised to discover that even when the periostracum is breached, pteropods can still mitigate damage by rebuilding the inner shell wall.

• A) To call for additional research on biological mechanisms that improve pteropod survival rates
• B) To discuss a conclusion drawn in a study of calcium carbonate's role in protecting the periostracum of pteropods
• C) To address some of the ways ocean acidification has altered pteropod behavior over time
• D) To present findings that suggest that a concern about the effects of ocean acidification on pteropod shells may be unwarranted

What's Required? Now we need the "big picture" - the main reason the author wrote this text. What's the central message?

The text starts by explaining a *concern*: pteropods are vulnerable to ocean acidification ("thought to be especially vulnerable"). Then, it presents findings from Peck et al. showing pteropods have protective mechanisms: the coating ("prevents this dissolution") and the ability to rebuild ("mitigate damage by rebuilding"). This directly challenges the initial concern, suggesting it might not be as severe as thought.

Correct Answer: (D)

• (A) The text presents findings, it doesn't explicitly *call for more* research. That's an inference not stated.
• (B) This gets the relationship wrong. The periostracum protects the calcium carbonate, not the other way around.
• (C) The text focuses on the *shells*, not the pteropods' *behavior*.

Question 8: Comparing Texts & Predicting Response

Based on the texts, how would the author of Text 2 most likely respond to what “some researchers contend” as described in Text 1?

Text 1
Little is known about how plate tectonics—wherein slabs of Earth’s crust move over, under, away from, and against one another—began. Some researchers contend that tectonic movements began around 3 billion years ago, often noting that computer models of Earth’s mantle temperature at the time indicate that the mantle would have been sufficiently molten to enable the plates to move.

Text 2
Ultimately, any plausible claim about the inception of tectonic movement must rest on empirical evidence from the geological record. Researcher Writtri Chowdhury and his team analyzed the geochemistry of zircon crystals to gain insight into the chemical composition of the magma from which the crystals formed and, based on the data, compellingly argue that plate tectonics may have been occurring as early as 4.2 billion years ago.

• A) By suggesting that the temperature of Earth's mantle 3 billion years ago was likely insufficient to allow for the level of tectonic movement predicted by computer models
• B) By distinguishing between computer models of Earth's mantle temperature that reliably predict the onset of plate tectonics and those that do not
• C) By indicating that computer models of Earth's mantle temperature are still being improved such that new models tend to be much more reliable than their predecessors
• D) By asserting that a more definitive form of evidence than the computer models suggests a different timeline for the onset of plate tectonics on Earth

What's Required? This is a two-text tango! First, understand the point Text 1 makes (researchers contend X based on computer models). Then, understand Text 2's main point (claims *must* rest on geological evidence). Finally, figure out how Text 2's author would view Text 1's contention.

Text 1 presents a claim based on computer models. Text 2 explicitly states that claims about plate tectonics *must* use "empirical evidence from the geological record." Text 2 then presents such geological evidence (zircon crystals) suggesting an *earlier* start date (4.2 billion years ago vs. 3 billion). Therefore, Text 2's author would argue that their geological evidence is stronger ("more definitive") than the computer models and points to a different time.

Correct Answer: (D)

• (A) Text 2 doesn't directly challenge the *temperature* model; it challenges the *type* of evidence used (models vs. rocks).
• (B) Text 2 dismisses models in favor of geological evidence; it doesn't differentiate *between* good and bad models.
• (C) Text 2 doesn't suggest models are improving; it champions a different kind of evidence altogether.