Text 1

Ecologists have long wondered how thousands of microscopic phytoplankton species can live together near ocean surfaces competing for the same resources. According to conventional wisdom, one species should emerge after outcompeting the rest. So why do so many species remain? Ecologists’ many efforts to explain this phenomenon still haven’t uncovered a satisfactory explanation.

Text 2

Ecologist Michael Behrenfeld and colleagues have connected phytoplankton’s diversity to their microscopic size. Because these organisms are so tiny, they are spaced relatively far apart from each other in ocean water and, moreover, experience that water as a relatively dense substance. This in turn makes it hard for them to move around and interact with one another. Therefore, says Behrenfeld’s team, direct competition among phytoplankton probably happens much less than previously thought.

Based on the texts, how would Behrenfeld and colleagues (Text 2) most likely respond to the “conventional wisdom” discussed in Text 1?

A) By asserting that it fails to recognize that routine replenishment of ocean nutrients prevents competition between phytoplankton species.

B) By suggesting that their own findings help clarify how phytoplankton species are able to compete with larger organisms.

C)By recommending that more ecologists focus their research on how competition among phytoplankton species is increased with water density.

D) By arguing that it is based on a misconception about phytoplankton species competing with one another.

Text 1

Africa’s Sahara region—once a lush ecosystem—began to dry out about 8,000 years ago. A change in Earth’s orbit that affected climate has been posited as a cause of desertification, but archaeologist David Wright also attributes the shift to Neolithic peoples. He cites their adoption of pastoralism as a factor in the region drying out: the pastoralists’ livestock depleted vegetation, prompting the events that created the Sahara Desert.

Text 2

Research by Chris Brierley et al. challenges the idea that Neolithic peoples contributed to the Sahara’s desertification. Using a climate-vegetation model, the team concluded that the end of the region’s humid period occurred 500 years earlier than previously assumed. The timing suggests that Neolithic peoples didn’t exacerbate aridity in the region but, in fact, may have helped delay environmental changes with practices (e.g., selective grazing) that preserved vegetation.

Based on the texts, how would Chris Brierley (Text 2) most likely respond to the discussion in Text 1?

A) By pointing out that given the revised timeline for the end of the Sahara’s humid period, the Neolithic peoples’ mode of subsistence likely didn’t cause the region’s desertification.

B) By claiming that pastoralism was only one of many behaviors the Neolithic peoples took part in that may have contributed to the Sahara’s changing climate.

C) By insisting that pastoralism can have both beneficial and deleterious effects on a region’s vegetation and climate.

D) By asserting that more research needs to be conducted into factors that likely contributed to the desertification of the Sahara region.

Text 1

Most animals can regenerate some parts of their bodies, such as skin. But when a three-banded panther worm is cut into three pieces, each piece grows into a new worm. Researchers are investigating this feat partly to learn more about humans’ comparatively limited abilities to regenerate, and they’re making exciting progress. An especially promising discovery is that both humans and panther worms have a gene for early growth response (EGR) linked to regeneration.

Text 2

When Mansi Srivastava and her team reported that panther worms, like humans, possess a gene for EGR, it caused excitement. However, as the team pointed out, the gene likely functions very differently in humans than it does in panther worms. Srivastava has likened EGR to a switch that activates other genes involved in regeneration in panther worms, but how this switch operates in humans remains unclear.

Based on the texts, what would the author of Text 2 most likely say about Text 1’s characterization of the discovery involving EGR?

A) It is reasonable given that Srivastava and her team have identified how EGR functions in both humans and panther worms.

B) It is unfairly dismissive given the progress that Srivastava and her team have reported.

C) It is overly optimistic given additional observations from Srivastava and her team.

D) It is unexpected given that Srivastava and her team’s findings were generally met with enthusiasm.

Text 1 Philosopher G.E. Moore’s most influential work entails the concept of common sense. He asserts that there are certain beliefs that all people, including philosophers, know instinctively to be true, whether or not they profess otherwise: among them, that they have bodies, or that they exist in a world with other objects that have three dimensions. Moore’s careful work on common sense may seem obvious but was in fact groundbreaking.

Text 2

External world skepticism is a philosophical stance supposing that we cannot be sure of the existence of anything outside our own minds. During a lecture, G.E. Moore once offered a proof refuting this stance by holding out his hands and saying,“Here is one hand, and here is another.” Many philosophers reflexively reject this proof (Annalisa Coliva called it “an obviously annoying failure”) but have found it a challenge to articulate exactly why the proof fails.

Based on the texts, how would the author of Text 1 most likely respond to proponents of the philosophical stance outlined in Text 2?

A) By agreeing with those proponents that Moore’s treatment of positions that contradict his own is fundamentally unserious.

B) By pointing out that Moore would assert that external world skepticism is at odds with other beliefs those proponents must unavoidably hold.

C) By arguing that if it is valid to assert that some facts are true based on instinct, it is also valid to assert that some proofs are inadequate based on instinct.

D) By suggesting that an instinctive distaste for Moore’s position is preventing external world skeptics from constructing a sufficiently rigorous refutation of Moore.

Text 1

A tiny, unusual fossil in a piece of 99-million-year-old amber is of the extinct species Oculudentavis khaungraae. The O.khaungraae fossil consists of a rounded skull with a thin snout and a large eye socket. Because these features look like they are avian, or related to birds, researchers initially thought that the fossil might be the smallest avian dinosaur ever found.

Text 2

Paleontologists were excited to discover a second small fossil that is similar to the strange O. khaungraae fossil but has part of the lower body along with a birdlike skull. Detailed studies of both fossils revealed several traits that are found in lizards but not in dinosaurs or birds. Therefore, paleontologists think the two creatures were probably unusual lizards, even though the skulls looked avian at first.

Based on the texts, what would the paleontologists in Text 2 most likely say about the researchers’ initial thought in Text 1?

A) It is reasonable because the O. khaungraae skull is about the same size as the skull of the second fossil but is shaped differently.

B) It is flawed because the researchers mistakenly assumed that O. khaungraae must be a lizard.

C) It is confusing because it isn’t clear what caused the researchers to think that O. khaungraae might be related to birds.

D) It is understandable because the fossil does look like it could be related to birds, even though O. khaungraae is probably a lizard.

Text 1

The fossil record suggests that mammoths went extinct around 11 thousand years (kyr) ago. In a 2021 study of environmental DNA (eDNA)—genetic material shed into the environment by organisms—in the Arctic, Yucheng Wang and colleagues found mammoth eDNA in sedimentary layers formed millennia later, around 4 kyr ago. To account for this discrepancy, Joshua H. Miller and Carl Simpson proposed that arctic temperatures could preserve a mammoth carcass on the surface, allowing it to leach DNA into the environment, for several thousand years.

Text 2

Wang and colleagues concede that eDNA contains DNA from both living organisms and carcasses, but for DNA to leach from remains over several millennia requires that the remains be perpetually on the surface. Scavengers and weathering in the Arctic, however, are likely to break down surface remains well before a thousand years have passed.

Which choice best describes how Text 1 and Text 2 relate to each other?

A) Text 1 discusses two approaches to studying mammoth extinction without advocating for either, whereas Text 2 advocates for one approach over the other.

B) Text 1 presents findings by Wang and colleagues and gives another research team’s attempt to explain those findings,whereas Text 2 provides additional detail that calls that explanation into question.

C) Text 1 describes Wang and colleagues’ study and a critique of their methodology, whereas Text 2 offers additional details showing that methodology to be sound. 

D) Text 1 argues that new research has undermined the standard view of when mammoths went extinct, whereas Text 2 suggests a way to reconcile the standard view with that new research.

Text 1

The idea that time moves in only one direction is instinctively understood, yet it puzzles physicists. According to the second law of thermodynamics, at a macroscopic level some processes of heat transfer are irreversible due to the production of entropy—after a transfer we cannot rewind time and place molecules back exactly where they were before, just as we cannot unbreak dropped eggs. But laws of physics at a microscopic or quantum level hold that those processes should be reversible.

Text 2

In 2015, physicists Tiago Batalhão et al. performed an experiment in which they confirmed the irreversibility of thermodynamic processes at a quantum level, producing entropy by applying a rapidly oscillating magnetic field to a system of carbon-13 atoms in liquid chloroform. But the experiment “does not pinpoint …​ what causes [irreversibility] at the microscopic level,” coauthor Mauro Paternostro said.

Based on the texts, what would the author of Text 1 most likely say about the experiment described in Text 2?

A) It would suggest an interesting direction for future research were it not the case that two of the physicists who conducted the experiment disagree on the significance of its findings.

B) It names the company where an important mathematician worked, details the mathematician’s career at the company,and provides an example of the recognition he received there.

C) It provides empirical evidence that the current understanding of an aspect of physics at a microscopic level must be incomplete.

D) It supports a claim about an isolated system of atoms in a laboratory, but that claim should not be extrapolated to a general claim about the universe.

Text 1

Despite its beautiful prose, The Guns of August, Barbara Tuchman’s 1962 analysis of the start of World War I, has certainweaknesses as a work of history. It fails to address events in Eastern Europe just before the outbreak of hostilities, thereby giving the impression that Germany was the war’s principal instigator. Had Tuchman consulted secondary works available to her by scholars such as Luigi Albertini, she would not have neglected the influence of events in Eastern Europe on Germany’s actions.

Text 2

Barbara Tuchman’s The Guns of August is an engrossing if dated introduction to World War I. Tuchman’s analysis of primary documents is laudable, but her main thesis that European powers committed themselves to a catastrophic outcome by refusing to deviate from military plans developed prior to the conflict is implausibly reductive.

Which choice best describes a difference in how the authors of Text 1 and Text 2 view Barbara Tuchman’s The Guns of August?

A)The author of Text 1 believes that the scope of Tuchman’s research led her to an incorrect interpretation, while the author of Text 2 believes that Tuchman’s central argument is overly simplistic.

B) The author of Text 1 argues that Tuchman should have relied more on the work of other historians, while the author of Text 2 implies that Tuchman’s most interesting claims result from her original research.

C) The author of Text 1 asserts that the writing style of The Guns of August makes it worthwhile to read despite any perceived deficiency in Tuchman’s research, while the author of Text 2 focuses exclusively on the weakness of Tuchman’s interpretation of events.

D) The author of Text 1 claims that Tuchman would agree that World War I was largely due to events in Eastern Europe,while the author of Text 2 maintains that Tuchman would say that Eastern European leaders were not committed to military plans in the same way that other leaders were.

Text 1

In a study of the benefits of having free time, Marissa Sharif found that the reported sense of life satisfaction tended to plateau when participants had two hours of free time per day and actually began to fall when they had five hours of free time per day. After further research, Sharif concluded that this dip in life satisfaction mainly occurred when individuals spent all their free time unproductively, such as by watching TV or playing games.

Text 2

Psychologist James Maddux cautions against suggesting an ideal amount of free time. The human desire for both free time and productivity is universal, but Maddux asserts that individuals have unique needs for life satisfaction. Furthermore, he points out that there is no objective definition for what constitutes productivity; reading a book might be considered a productive activity by some, but idleness by others.

Based on the texts, how would Maddux (Text 2) most likely respond to the conclusion Sharif (Text 1) reached after her further research?

A) By acknowledging that free time is more likely to enhance life satisfaction when it is spent productively than when it is spent unproductively.

B) By challenging the reasoning in Text 1, as it has not been proved that productivity commonly contributes to individuals’ life satisfaction.

C) By warning against making an overly broad assumption, as there is no clear consensus in distinguishing between productive and unproductive activities.

D) By claiming that the specific activities named in Text 1 are actually examples of productive activities rather than unproductive ones.

Text 1

Fossils of the hominin Australopithecus africanus have been found in the Sterkfontein Caves of South Africa, but assigning an age to the fossils is challenging because of the unreliability of dating methods in this context. The geology of Sterkfontein has caused soil layers from different periods to mix, impeding stratigraphic dating, and dates cannot be reliably imputed from those of nearby animal bones since the bones may have been relocated by flooding.

Text 2

Archaeologists used new cosmogenic nuclide dating techniques to reevaluate the ages of A. africanus fossils found in the Sterkfontein Caves. This technique involves analyzing the cosmogenic nucleotides in the breccia—the matrix of rock.Fragments immediately surrounding the fossils. The researchers assert that this approach avoids the potential for misdating associated with assigning ages based on Sterkfontein’s soil layers or animal bones.

Based on the texts, how would the researchers in Text 2 most likely respond to the underlined portion in Text 1?

A) They would emphasize the fact that the A. africanus fossils found in the Sterkfontein Caves may have been corrupted in some way over the years.

B) They would contend that if analyses of surrounding layers and bones in the Sterkfontein Caves were combined, then the dating of the fossils there would be more accurate.

C) They would claim that cosmogenic nuclide dating is reliable in the context of the Sterkfontein Caves because it is applied to the fossils directly.

D) They would argue that their techniques are better suited than other methods to the unique challenges posed by the Sterkfontein Caves.