Explicit Details

The Fleischmann’s glass frog (*Hyalinobatrachium fleischmanni*) exhibits a unique adaptation to evade predators during sleep. Researchers have found that while sleeping, the frog sequesters approximately 89 percent of its red blood cells within its liver. Because the frog's skin and muscles are translucent, hiding these pigment-rich red blood cells makes the frog's body nearly transparent, allowing it to blend seamlessly into surrounding leaves. Once the frog wakes up and becomes active, the red blood cells exit the liver and resume circulation throughout the body, restoring its typical color and activity levels.

Based on the text, what is true of a Fleischmann's glass frog when it is awake and active?

The Antarctic toothfish (*Dissostichus mawsoni*) thrives in the freezing waters of the Southern Ocean surrounding Antarctica. To survive in temperatures that frequently drop below $0^\circ\text{C}$, the fish relies on specialized proteins known as glycoproteins. These glycoproteins, which are synthesized in the liver and released into the bloodstream, bind to tiny ice crystals inside the fish's body. By attaching to these crystals, the glycoproteins prevent them from growing larger and damaging the fish's cellular structures, thereby allowing the toothfish to remain active without its blood freezing solid.

According to the text, which statement is true about the glycoproteins in the Antarctic toothfish?

Unlike the warm, high-salinity waters of the Mediterranean, which host wood-boring shipworms (*Teredo navalis*) that rapidly consume submerged timber, the Baltic Sea possesses a unique environment that preserves wooden shipwrecks for centuries. The Baltic Sea is characterized by low salinity levels, typically ranging from $3$ to $15$ parts per thousand, which is far below the threshold required for *Teredo navalis* to survive and reproduce. Consequently, wooden vessels like the seventeenth-century warship *Vasa* remained nearly intact until their salvage. However, these wrecks are not entirely immune to decay; low-oxygen-tolerant soft-rot fungi and erosion bacteria slowly degrade the wood fibers over long periods, albeit at a drastically reduced rate compared to warm-water wood-borers.

Based on the text, what is true of the decay of wooden shipwrecks in the Baltic Sea?

The Great Mosque of Djenné in Mali is constructed entirely of mud-bricks. To prevent the walls from cracking under the intense heat, builders incorporate projecting wooden rods called *toron*. These rods absorb the physical tension caused by temperature shifts. During the annual festival, the *toron* also serve as support scaffolding for workers replastering the building.

According to the text, what is one function of the *toron*?

In vascular plants, the phloem transports photoassimilates through sieve tube elements, which are connected by perforated sieve plates. When a plant experiences mechanical wounding or pathogen attack, it rapidly deposits callose—a $\beta$-1,3-glucan polymer—around these perforations. Researchers led by Dr. Evelyn Vance studied *Arabidopsis thaliana* mutants lacking the callose synthase gene *CalS7*. The team observed that while wild-type plants completely sealed their sieve plates within twenty minutes of a puncture wound, the *cals7* mutants showed no callose deposition at the wound site even after two hours. Surprisingly, however, the rate of photoassimilate translocation in the wounded *cals7* mutants decreased by only $15\%$ compared to pre-wound levels, indicating that callose deposition is not the sole mechanism restricting transport after injury.

Based on the text, what is true of the *cals7* mutants studied by Vance's team?

In 1947, archaeologist G. Lankester Harding led the excavation of the Qumran Caves, where his team discovered the first batch of the Dead Sea Scrolls. While most of these ancient manuscripts were written on parchment made from animal skins, a unique document called the Copper Scroll was engraved on thin sheets of metal. Additionally, though the majority of the manuscripts were written in Hebrew, a few were written in Aramaic and Greek.

According to the text, which statement is true about the Copper Scroll?

Mineral dust particles transported from arid regions play a complex role in polar climate systems. While light-colored dust typically increases the albedo of snow surfaces, high concentrations of iron-rich mineral dust can lower albedo, accelerating ice melt. Crucially, climatologist Dr. Elena Rostova's 2024 study of the Greenland Ice Sheet demonstrated that this melting is not uniform; rather, the dust particles aggregate in cryoconite holes—small water-filled depressions on the glacier surface. Rostova found that these cryoconite accumulations absorb solar radiation at a rate 15% higher than surrounding clean ice, creating localized thermal pockets that deepen the holes rather than spreading laterally across the ice sheet. Consequently, while regional albedo is altered, the primary physical degradation of the ice sheet occurs vertically within these distinct micro-structures.

Based on the text, why do iron-rich mineral dust accumulations deepen cryoconite holes rather than spreading laterally?

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?

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?

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?

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?

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?

Ancient Roman marine structures, such as breakwaters and piers, have endured for over $2\text{,000}$ years despite constant exposure to seawater. Modern research reveals that this durability is due to the chemical composition of the concrete used. The Romans mixed volcanic ash, known as pozzolana, with quicklime and seawater. This combination initiated a chemical reaction, yielding a rare silicate mineral called aluminum-tobermorite ($Al\text{-tobermorite}$). When seawater subsequently percolates through the concrete, it reacts with the remaining volcanic components, causing new $Al\text{-tobermorite}$ crystals to form. Rather than eroding the material, this continuous exposure to seawater causes the crystals to grow and interlock within the pores of the concrete, thereby reinforcing the structural integrity of the barrier over time.

Based on the text, what is true of the aluminum-tobermorite crystals in Roman marine concrete?

The giant isopod (*Bathynomus giganteus*) is a deep-sea crustacean that inhabits the cold, benthic zones of the Atlantic, Pacific, and Indian Oceans. Because food is scarce in these deep-sea environments, *B. giganteus* has adapted to function as a scavenger, feeding primarily on the carcasses of fallen whales, fish, and squid. When food is abundant, the isopod can gorge itself to the point of compromising its locomotive ability. Conversely, when resources are depleted, *B. giganteus* can survive long periods of starvation. In laboratory settings, researchers observed that captive giant isopods could survive for over five years without consuming any food, relying on their highly efficient, slow metabolic rates to sustain vital bodily functions during extended periods of resource scarcity.

Based on the text, what is true of *Bathynomus giganteus* when resources are scarce in its environment?

The hoatzin (Opisthocomus hoazin), a tropical bird native to the Amazon and Orinoco basins, possesses an unusual digestive system. Unlike most birds, which rely on a muscular gizzard to grind seeds and insects, the hoatzin is a strict folivore, feeding almost exclusively on leaves. To digest this fibrous diet, the bird utilizes foregut fermentation, a process facilitated by a highly enlarged crop and lower esophagus. Specialized symbiotic bacteria in these organs break down cellulose before the food reaches the stomach. While this adaptation allows the hoatzin to extract nutrients from otherwise indigestible foliage, it has a significant trade-off: the heavy, filled crop restricts the development of the bird's breastbone and flight muscles, making the hoatzin a notoriously weak and clumsy flyer.

Based on the text, what is true of the hoatzin's digestive system?

The single-celled slime mold *Physarum polycephalum* lacks a central nervous system, yet it exhibits complex decision-making behavior. In a study led by biophysicist Toshiyuki Nakagaki, researchers placed the organism in a maze with two food sources—oat flakes—positioned at the entrance and exit. The slime mold initially expanded its body to occupy the entire maze. Over several hours, however, the organism retracted its tubular networks from dead ends and consolidated its cytoplasm into a single, thick tube connecting the two food sources. This pathway represented the shortest possible route through the maze, demonstrating that the cell could compute mathematical optimizations through physical feedback loops.

Based on the text, what did *Physarum polycephalum* do when first introduced to the maze?

The *Welwitschia mirabilis* is a unique gymnosperm plant endemic to the Namib Desert, characterized by its ability to survive in extremely arid conditions. Although it possesses a taproot, this root system is relatively shallow and does not reach deep groundwater reserves. Instead, *Welwitschia mirabilis* relies on fog that rolls in from the Atlantic Ocean. The fog condenses on its two broad, continuously growing leaves. The plant then absorbs this moisture directly through specialized epidermal cells, rather than through its stomata, which primarily function in gas exchange during photosynthesis. This direct absorption allows the plant to maintain hydration even when soil moisture is virtually non-existent.

Based on the text, which statement is true about how *Welwitschia mirabilis* obtains moisture?

The Chand Baori in Rajasthan, India, is one of the deepest stepwells in the world, built in the ninth century to conserve water in the arid region. The structure features over $3\text{}500$ narrow steps arranged in perfect symmetry, descending $13$ stories. Uniquely, the air at the bottom of the well remains consistently $5$ to $6$ degrees cooler than at the surface. Historical records show that the stepwell served not only as a crucial water reservoir but also as a community gathering place during periods of intense heat, with royalty using the adjacent pavilions for theatrical performances. However, modern geological surveys indicate that the local water table has receded significantly, leaving the lowest levels of the well dry for several decades.

Based on the text, what is true of the Chand Baori?

The Antarctic icefish (family Channichthyidae) lives in the extremely cold waters of the Southern Ocean. Unlike all other known vertebrates, icefish lack hemoglobin, the iron-rich protein that transports oxygen through the blood, leaving their blood translucent. To compensate for this absence, icefish have evolved several physiological adaptations: they possess exceptionally large hearts, a high volume of circulating blood, and a dense network of capillaries. Furthermore, icefish can absorb oxygen directly through their scaleless skin from the highly oxygenated polar waters. Despite these adaptations, their oxygen-carrying capacity is only about ten percent of that of typical red-blooded fish, restricting them to stable, cold environments where oxygen levels remain high.

Based on the text, what is true of the oxygen-carrying capacity of the Antarctic icefish's blood?

The green sea slug *Elysia chlorotica* is known for its ability to perform photosynthesis, a process typically reserved for plants. The slug achieves this by consuming the algae *Vaucheria litorea* and retaining its chloroplasts—the organelles responsible for photosynthesis—within its own digestive cells. This biological phenomenon, known as kleptoplasty, allows *E. chlorotica* to survive for up to nine months solely on light and carbon dioxide. While the slug extracts these chloroplasts, it does not inherit the algal genes required to maintain them. Instead, the chloroplasts eventually degrade, requiring the slug to feed on algae periodically throughout its life cycle to replenish them.

According to the text, which statement is true about the chloroplasts inside *Elysia chlorotica*?