Information and Ideas

Stomatal density on the leaves of *Ginkgo biloba* is inversely proportional to atmospheric carbon dioxide ($CO_2$) concentrations, a relationship widely utilized by paleoclimatologists to reconstruct ancient climates. However, recent chamber experiments demonstrate that when *G. biloba* saplings are grown under highly fluctuating diurnal temperatures, their stomatal development becomes erratic, decoupling from $CO_2$ levels and exhibiting highly variable densities that mimic both hyper-arid and humid ancient profiles. Consequently, fossilized leaf samples of *G. biloba* collected from geological strata associated with high-frequency thermal instability may lead to erroneous climate reconstructions unless researchers can verify that ______

Which choice most logically completes the text?

In alpine ecosystems, the cushion plant *Silene acaulis* (moss campion) relies on insects for pollination. However, insect activity typically decreases at higher elevations due to colder temperatures. Evolutionary biologist Dr. Sofia Gomez hypothesized that *S. acaulis* populations in pollinator-scarce, high-altitude environments adapt by increasing their rate of autonomous self-pollination (generating seeds without insect assistance) to ensure reproduction, despite the cost of lower genetic diversity. To test this hypothesis, Gomez's team analyzed pollinator visitation rates, self-pollination rates, and genetic diversity in several *S. acaulis* populations across a range of elevations. Which finding, if true, would most directly support Gomez's hypothesis?

In many mid-sized cities, municipal governments have converted central public parking lots into cargo distribution hubs to optimize local delivery logistics for digital retailers. Urban planner Clara Vance monitored pedestrian activity and business revenues in several such cities before and after the hub installations. Vance found that although local online delivery times decreased by $40\%$, overall pedestrian foot traffic in the surrounding commercial districts fell by nearly $30\%$ due to the reduction in parking. Additionally, retail businesses in these districts that lacked online ordering options experienced a sharp decline in sales, while those that transitioned to delivery-based models maintained or increased their revenues. This suggests that _______

Which choice most logically completes the text?

To trace ancient Mediterranean trade routes, archaeologists analyze trace element concentrations to source obsidian artifacts to specific volcanic flows. Strontium-to-yttrium ratios have long been used to distinguish between different obsidian sources. However, geologist Clara Vance showed that obsidian from two Melian sources, Sta Nychia and Demenegaki, has overlapping strontium-to-yttrium ratios due to a shared magmatic origin. To distinguish between them, Vance measured the barium-to-zirconium ratio, which differs significantly between the two flows due to localized crystallization during cooling. Thus, an archaeologist who detects a typical Melian strontium-to-yttrium signature in an artifact but does not evaluate its barium-to-zirconium ratio ______

Which choice most logically completes the text?

The Pompeii worm (*Alvinella pompejana*) thrives near deep-sea hydrothermal vents, experiencing temperature gradients ranging from $20^\circ\text{C}$ to over $80^\circ\text{C}$. To survive these extreme thermal fluctuations, the worm is coated with a thick layer of epibiotic bacteria. Researchers led by Dr. Elena Vance investigated this relationship and discovered that these bacteria secrete a specialized mucus rich in heat-shock proteins. Rather than acting as a simple physical barrier, this secretion actively modulates the localized chemical environment by binding to heavy metal ions present in the vent emissions, thereby preventing toxic accumulation in the worm’s epidermal cells. However, the study noted that the bacteria rely entirely on the worm’s vascularized parapodia to obtain oxygen from the surrounding water, showing that the symbiosis is mutually dependent for gas exchange and detoxification.

According to the text, which statement is true about the mucus secreted by the epibiotic bacteria on the Pompeii worm?

Astronomers studying the remote exoplanet Kepler-186f have long debated its atmospheric composition. While early observations suggested a dense shroud of carbon dioxide, recent spectrographic data collected by a space telescope revealed high concentrations of methane and water vapor, alongside a complete absence of detectable carbon dioxide. Because methane is rapidly broken down by the radiation of the host star, Kepler-186, it must be continuously replenished by an active source on the planet’s surface. Which choice most logically completes the text?

The western redcedar holds immense significance for the Coast Salish peoples of the Pacific Northwest. To harvest its bark without harming the tree, gatherers traditionally peel only a single narrow strip from a living trunk, allowing the tree to continue growing. Once harvested, this versatile material is split, dried, and woven into essential items such as hats, baskets, and clothing. Because the bark naturally repels water, garments crafted from it provide excellent protection against the region's wet climate.

Based on the text, what is true about the harvesting of western redcedar bark?

In 1706, paint maker Johann Jacob Diesbach accidentally synthesized Prussian blue, the first modern synthetic pigment, while attempting to create a cochineal red. Prior to this discovery, artists relied on ultramarine, a prohibitively expensive pigment ground from lapis lazuli imported from Afghanistan. Prussian blue offered a vibrant, lightfast alternative at a fraction of the cost, quickly spreading across European studios and altering the color palettes of the eighteenth century. More than just a tool for artists, the pigment's unique chemical formulation allowed scientists to study cyanides and cellular respiration, thereby bridging the divide between artistic innovation and early biochemistry. Ultimately, Prussian blue did not merely substitute for ultramarine; it catalyzed developments in both the visual arts and scientific inquiry.

Which choice best states the main idea of the text?

Many desert reptiles are active primarily during the early morning and late evening, when air temperatures are moderate. During the hottest hours of the day, these reptiles retreat into deep underground burrows, where temperatures remain significantly cooler than at the surface. Because these species cannot internally regulate their body temperature, they rely entirely on external environments to avoid overheating. If surface temperatures remain excessively high for an extended portion of the day, the reptiles must remain in their burrows to survive. Which choice most logically completes the text?

Many forest tree species form symbiotic relationships with mycorrhizal fungi, which supply the trees with nutrients and water in exchange for carbon. Ecologist Dr. Elena Ruiz hypothesized that during prolonged drought periods, this relationship shifts: rather than maintaining mutual benefit, certain mycorrhizal species become parasitic, consuming carbon from host trees without providing a corresponding increase in water uptake. To test this hypothesis, Ruiz monitored carbon allocation and water uptake in Douglas fir (*Pseudotsuga menziesii*) saplings inoculated with either fungus species A or fungus species B under simulated drought conditions.

Which finding, if true, would most directly support Ruiz's hypothesis?

The hydraulis, a precursor to the modern pipe organ invented by Ctesibius of Alexandria in the third century BCE, relied on a unique water-based system to regulate wind pressure. While earlier wind instruments depended entirely on the variable lung capacity of the performer, the hydraulis utilized a reservoir of water situated beneath a metal chamber. Air pumped into this chamber displaced the water, which in turn exerted a steady, upward hydrostatic pressure on the air. This pressurized air was then directed into the pipes when the keys were depressed. Although later Roman engineers replaced the water reservoir with weighted bellows to simplify the instrument’s transport, the original Greek design was highly praised by contemporaries specifically for its ability to maintain a remarkably consistent tone during extended performances.

According to the text, which statement is true about the original Greek hydraulis?

For decades, historians assumed that the transition from foraging to farming in the Fertile Crescent was a sudden, localized event driven entirely by sudden climatic shifts at the end of the Younger Dryas period. However, recent archaeological findings at sites like Göbekli Tepe and Tell Qaramel suggest a more gradual, culturally driven transition. At these locations, hunter-gatherer communities constructed monumental stone structures and established semi-permanent settlements long before the widespread domestication of wild grains. These discoveries indicate that complex social organization and communal ritual activity preceded—and likely facilitated—the development of agriculture, rather than being mere consequences of it.

Which choice best states the main idea of the text?

Marine biologist Dr. Sofia Rossi and her team investigated the resilience of two key Caribbean reef-building coral species, *Acropora cervicornis* and *Porites astreoides*, under elevated sea surface temperatures. Corals rely on calcification to build their calcium carbonate skeletons, a process that is often impaired by thermal stress. Rossi hypothesized that while both species would exhibit reduced calcification rates when exposed to heat stress, the structurally denser *Porites astreoides* would demonstrate greater thermal tolerance, maintaining a significantly higher calcification rate than *Acropora cervicornis* at elevated temperatures.

Mean Calcification Rates of Two Coral Species at Different Temperatures:

Which choice most effectively uses data from the table to support Dr. Rossi's hypothesis?

The plant *Alyssum bertolonii* is known as a hyperaccumulator because it absorbs high concentrations of nickel from soil. While high levels of nickel are toxic to most herbivores, *A. bertolonii* suffers very little insect damage. Because the nickel is stored in the outer leaf tissues, scientists hypothesize that the metal acts as a chemical defense. To test this, researchers grew *A. bertolonii* in nickel-depleted soil. If the hypothesis is correct, insects fed with leaves from these plants would be expected to ______

Which choice most logically completes the text?

In the late nineteenth century, Harvard College Observatory director Edward Pickering hired a group of women, later known as the "Harvard Computers," to process astronomical data. Among them was Williamina Fleming, who developed a classification system for stars based on the amount of hydrogen observed in their spectra. Fleming organized the stars alphabetically from A to Q, with "A" stars possessing the most prominent hydrogen lines. While Pickering later modified this system with Annie Jump Cannon to reorganize the categories by stellar temperature rather than hydrogen abundance, Fleming's initial system cataloged over ten thousand stars and established the foundational methodology of spectral analysis. Crucially, Fleming's cataloging relied on examining photographic glass plates rather than observing stars directly through a telescope, a practice that allowed her to identify numerous novae and nebulae.

Based on the text, what is true of Williamina Fleming's stellar classification system?

Botanists once classified plant secondary metabolites—organic compounds like alkaloids and flavonoids not directly involved in growth or development—primarily as metabolic waste products. More recent studies, however, show that these substances are integral to a plant’s survival strategies. Rather than serving as passive byproducts, secondary metabolites mediate crucial ecological relationships by deterring herbivores, attracting pollinators, and facilitating chemical signaling between neighboring plants. Thus, the synthesis of these compounds represents a highly adaptive evolutionary response to environmental pressures rather than a simple elimination of cellular waste.

Which choice best states the main idea of the text?

Historian Dr. Neil Clere and colleagues studied 14th-century maritime trade between East Africa and the Indian subcontinent. They hypothesized that while elite historical archives primarily highlight luxury goods like silk and porcelain, the bulk of the trade volume and economic activity actually consisted of mundane agricultural commodities like grain and timber, which left fewer traces in official customs records. Which finding, if true, would most directly support Clere and colleagues' hypothesis?

During the early twentieth century, historians often argued that the introduction of print technology in sixteenth-century Safavid Iran was resisted primarily due to religious opposition. However, recent archival research shows that Safavid scribes and calligraphers occupied prestigious positions within the state administration, where their handwritten documents served as essential symbols of royal authority. Furthermore, the Safavid court actively subsidized scribal guilds to produce manuscripts even when cheaper, imported printed texts from Europe were available in local markets. This evidence suggests that the state's preference for handwritten texts over print was primarily motivated by

Which choice most logically completes the text?

Silbo Gomero is a whistled language used by inhabitants of La Gomera in the Canary Islands to communicate across deep ravines. Historically, researchers assumed Silbo Gomero was a simplified code with limited communicative range. However, a 2005 study by linguist Manuel Carreiras and colleagues disproved this assumption. Using functional magnetic resonance imaging (fMRI), the researchers monitored the brain activity of both fluent whistlers ('silbadores') and non-whistlers while they listened to whistled Spanish sentences. The fMRI scans revealed that in fluent whistlers, listening to Silbo Gomero activated the left temporal lobe—the region traditionally associated with processing spoken language. In contrast, in non-whistlers, the whistled signals only activated the right hemisphere regions associated with sound recognition, suggesting that the brain processes whistled language as linguistic data only when the individual is fluent in that language.

Based on the text, what is true about the brain activity of non-whistlers when they listened to Silbo Gomero?

For decades, marine biologists assumed that bioluminescence in deep-sea organisms served primarily as a mechanism for attracting mates in the pitch-black bathypelagic zone. However, recent studies of various organisms, including the anglerfish and certain species of jellyfish, suggest a far more complex utility. Researchers have observed these creatures utilizing bioluminescent displays to startle predators, camouflage themselves against downwelling light through counterillumination, and even signal to larger predators to consume their attackers. Consequently, bioluminescence is now understood not merely as a reproductive aid, but as a sophisticated, multi-functional tool critical for survival in high-risk marine environments.

Which choice best states the main idea of the text?