Tüm alıştırma soruları

During the excavation of the ancient ruins, although the archaeologist carefully brushed away the dust she still could not decipher the faint carvings on the stone tablet.

Which choice is the best version of the underlined portion?

Two students debate the mechanism driving thermal activity on the icy moon Enceladus-Prime.

Student 1 (Tidal Flexing Model)
Tectonic activity and hydrothermal plumes are driven by tidal dissipation. The gravitational pull of the host planet flexes the moon's ice shell, generating heat. The rate of heat generation is directly proportional to the orbital eccentricity (non-circularity) of the moon. Any change in orbital parameters immediately alters the heat output and plume temperatures.

Student 2 (Radiogenic Core Model)
Heat is generated exclusively by the radioactive decay of unstable isotopes in the moon's silicate core. This thermal energy slowly conducts through the ice shell. The heat production rate is constant on short timescales, unaffected by orbital motion or eccentricity, and decreases gradually over millions of years as the isotopes decay.

Match each of the following hypothetical observations with the viewpoint it supports or contradicts.

### Models of the Formation of the Moon

How the Moon formed is a fundamental question in planetary science. Scientists have proposed several models to explain its origin, chemical composition, and orbital dynamics.

Model 1 (Giant Impact Model)
This model proposes that approximately 4.5 billion years ago, a Mars-sized protoplanet named Theia collided with the proto-Earth. The collision released immense energy, vaporizing the outer layers of both bodies. This vaporized rock was ejected into orbit around Earth, cooled, and accreted to form the Moon. Because volatile elements (such as water, sodium, and potassium) vaporize easily and were lost to space during the high-temperature event, the Moon is highly depleted in these volatiles. The model also accounts for the Moon's small iron core, as the iron from the impactor sunk to Earth's core.

Model 2 (Capture Model)
This model proposes that the Moon formed independently in another region of the solar system, with its own distinct chemical signature. As the Moon passed close to the proto-Earth, Earth's gravitational pull captured it into a permanent orbit. Because a passing body typically accelerates and escapes gravity, this model requires a mechanism to slow the Moon down during its encounter. Proponents suggest that tidal forces, gravitational interactions with other protoplanets, or friction from a thick, primordial atmosphere dissipated the Moon's kinetic energy, allowing capture.

Model 3 (Fission Model)
This model proposes that the early Earth rotated so rapidly on its axis that centrifugal force exceeded gravitational force at the equator. A large portion of Earth's mantle was thrown off, eventually accreting in orbit to form the Moon. Since the Moon would be composed entirely of Earth's mantle material, this model explains why the Moon's bulk density is similar to that of Earth's mantle. However, the model requires an exceptionally high initial angular momentum that is difficult to reconcile with the current Earth-Moon system's dynamics.

Based on the passage, match each model with the physical mechanism, assumption, or prediction that is unique to that model.

The following passage is about the Svalbard Global Seed Vault.

Deep within the permafrost of a remote Arctic island, one of humanity’s most vital backup systems lies buried. The Svalbard Global Seed Vault, located on the Norwegian archipelago of Svalbard, safeguards millions of seeds representing thousands of crop species from around the globe. Operating as a safety net for biodiversity, the vault functions as a secure repository to prevent accidental loss of plant genetics. Designed to withstand both natural disasters and man-made catastrophes, the heavily fortified facility serves as an ultimate insurance policy for the world's food supply. Inside this subterranean facility, crates of seeds are carefully stored and kept at a constant temperature of minus eighteen degrees Celsius, ensuring their viability for decades, if not centuries.

[1]

Historically, genebanks around the world have been vulnerable to wars, political instability, civil strife, and catastrophic natural disasters, which can easily obliterate decades of agricultural heritage in an instant. For instance, national seed vaults in Iraq and Afghanistan were completely destroyed during recent conflicts, resulting in the loss of irreplaceable crop varieties. Similarly, a powerful typhoon in the Philippines severely flooded and damaged another crucial depository, highlighting the vulnerability of centralized storage. By storing duplicate copies of these seeds in the stable, remote, and geologically inactive environment of Svalbard, participating countries can rebuild their agricultural systems if their domestic seed collections are lost. Ultimately, the vault represents a global effort to preserve agricultural biodiversity and secure future food systems against unpredictable global threats.

Given that all the choices are true, which choice at [1] provides the most effective transition from the preceding paragraph to the rest of the second paragraph?

In temperate forests around the world, bioluminescent fungi grow on decaying wood, casting a faint green glow on the forest floor. These organisms emit light through a chemical reaction involving the pigment luciferin, however, researchers are still investigating the precise evolutionary advantages of this phenomenon. Some scientists hypothesize that the glow attracts nocturnal insects that help disperse the fungi's spores, while others believe it deters predators.

Which of the following choices is the best replacement for the underlined portion?

Although modern digital sensors have largely replaced film in commercial theaters, archivists still work tirelessly to preserve original celluloid reels. Cellulose nitrate, the medium used for early cinema, is highly unstable and prone to rapid decay. To prevent the loss of these historical artifacts, specialists must handle the fragile materials with meticulous care during the digitization process.

Which choice best maintains the tone established in the passage?

To prevent an inconsistent shift in verb tense, write the appropriate form of the verb 'assess' in the blank.

The following passage is an excerpt from a biography of geologist Marie Tharp.

In the mid-twentieth century, geologist Marie Tharp painstakingly plotted thousands of sonar measurements to create the first comprehensive map of the Atlantic Ocean floor. At the time, most scientists believed the seabed was a flat, featureless plain. Tharp’s work, however, revealed a massive underwater rift valley splitting the ocean floor. Although her colleague, Bruce Heezen, initially dismissed her findings as 'girl talk,' he, along with several other skeptical members of the department, later realizes she was correct. The map they published in 1977 ultimately changed the way scientists understood plate tectonics.

Which of the following options represents the correct form of the underlined verb to maintain consistent verb tense in the passage?

A portion of the passage below is underlined.

In 1974, a supermarket in Troy, Ohio, made history by scanning the first commercial barcode on a pack of chewing gum. This milestone was the culmination and final result of decades of research that had been done by inventors who sought a way to automate grocery checkout lanes.

Which of the following options represents the most effective way to write the underlined portion of the sentence?

A certain metal alloy is made of copper, zinc, and nickel. By weight, $\frac{1}{4}$ of the alloy is copper, and $30\%$ of the alloy is zinc. What fraction of the alloy is nickel?

### The Solar Corona Heating Problem

The Sun’s surface, the photosphere, has a temperature of approximately $5,800\text{ K}$, while the corona, the outermost layer of the solar atmosphere, reaches temperatures of over $1,000,000\text{ K}$. Because heat normally flows from hotter to cooler regions, this temperature inversion is a major puzzle in astrophysics. Two scientists propose different hypotheses to explain how energy is transported to heat the corona.

Scientist 1
Energy is transported from the photosphere to the corona by magnetic waves called Alfvén waves. These are low-frequency transverse waves that propagate along magnetic field lines. Convection in the photosphere shakes the magnetic field lines, generating these waves. As the Alfv��n waves travel outward through the solar atmosphere into regions of lower plasma density, they become unstable, dissipate, and transfer their electromagnetic energy directly to the coronal plasma as thermal energy. The heating is continuous and occurs globally across all magnetic field structures.

Scientist 2
Energy is transported and released in the corona through a process called magnetic reconnection. The Sun's magnetic field lines are continuously twisted and sheared by the motion of photospheric plasma. When oppositely directed magnetic field lines are forced together, they rapidly break and reconnect, releasing stored magnetic energy. This energy release occurs in sudden, localized bursts called nanoflares. The cumulative effect of millions of these tiny, impulsive nanoflares occurring throughout the corona provides the energy necessary to maintain the high coronal temperature.

According to Scientist 1, which of the following is a necessary condition for Alfvén waves to transfer thermal energy to the solar corona?

Although both Marie Curie and Rosalind Franklin made groundbreaking contributions to chemistry, Curie's research was ultimately widely recognized, with her two Nobel Prizes rendering her legacy more celebrated then Franklin.

Which choice makes the comparison in the sentence grammatically correct and logical?

What is the value of the mathematical expression below?

An explorer records the elevation, in meters relative to sea level, of four research stations: $W$, $X$, $Y$, and $Z$. Station $W$ is located at an elevation of $-15$ meters. The elevation of Station $X$ is the absolute value of the elevation of Station $W$. The elevation of Station $Y$ is $8$ meters lower than the elevation of Station $X$. Station $Z$ is at an elevation such that the distance between the elevations of Station $Y$ and Station $Z$ on a vertical number line is exactly $12$ meters. Which of the following could be the elevation, in meters, of Station $Z$?

Having spent decades in the archives of the university library, the professor's research on the Gutenberg Bible was finally complete.

Which of the following choices best corrects the underlined portion of the sentence?

The deep-sea research team discovered that the hydrothermal vent organisms, which thrive in complete darkness, are entirely deprived from the sunlight that powers photosynthetic ecosystems near the surface.

Which of the following is the most grammatically and idiomatically correct replacement for the underlined portion of the sentence?

When scientists captured a living coelacanth off the coast of South Africa in 1938, they were shocked to find a prehistoric fish that had previously been thought to be extinct and no longer living.

Which choice is the most effective and concise option for the underlined portion of the sentence?

### Younger Dryas Debate

The Younger Dryas was a period of abrupt cooling that occurred approximately $12,900$ years ago. Two viewpoints discuss the potential cause of this event.

Meltwater Flood Model
A sudden influx of freshwater from the melting Laurentide Ice Sheet entered the North Atlantic Ocean. This freshwater cap was less dense than the saline ocean water, preventing the sinking of cold water and shutting down the Atlantic Meridional Overturning Circulation (AMOC). Without this ocean conveyor belt, heat transport to the high northern latitudes ceased, causing rapid cooling. This model predicts that cooling was localized to the North Atlantic region, and that North Atlantic sea surface salinity dropped abruptly.

Cosmic Impact Model
A fragmenting comet or asteroid collided with or exploded over the Laurentide Ice Sheet. The impact triggered widespread biomass burning and threw massive amounts of dust, soot, and sulfur aerosols into the upper atmosphere, blocking incoming sunlight. This model predicts that the cooling was global, occurring simultaneously in both the Northern and Southern Hemispheres, and that a distinct layer containing impact indicators (such as platinum anomalies) and soot was deposited globally at the start of the event.

Suppose researchers analyze marine sediment cores from the Southern Ocean, located in the Southern Hemisphere, and find that sea surface temperatures in this region did not decrease during the Younger Dryas, but instead continued a gradual warming trend. This finding is consistent with which model(s)?

A student took a history exam containing $80$ questions. If the student answered $15\%$ of the questions incorrectly, how many questions did the student answer correctly?

### Models of Solar Corona Heating

The temperature of the Sun's surface (photosphere) is approximately $5{}800\text{ K}$, yet the solar corona (the outermost layer of the solar atmosphere) reaches temperatures of over $1{}000{}000\text{ K}$. Scientists have proposed two primary models to explain how energy is transported from the relatively cool photosphere to heat the extremely hot corona.

Model 1 (Wave Heating Model)
This model proposes that magnetohydrodynamic (MHD) waves, specifically Alfvén waves, are generated by turbulent convective motions of plasma in the photosphere. These waves travel upward along magnetic field lines into the corona. Because the density of the solar atmosphere decreases rapidly with altitude, the amplitude of these waves grows until they become non-linear and damp, transferring their mechanical and magnetic energy directly into the coronal plasma as thermal energy. Under this model, heating occurs continuously and is distributed smoothly across magnetic loops.

Model 2 (Magnetic Reconnection Model)
This model, also known as the nanoflare model, proposes that coronal heating is driven by magnetic reconnection. The footpoints of coronal magnetic loops are constantly twisted and sheared by plasma movements in the photosphere, storing magnetic energy in the corona. When the magnetic field lines become highly tangled, they spontaneously break and reconnect in millions of localized, impulsive bursts called nanoflares. Each nanoflare releases energy that heats the surrounding plasma to temperatures exceeding $10{}000{}000\text{ K}$, which then cools down to the average coronal temperature. Under this model, coronal heating is highly episodic and localized.

Based on the models, which of the following statements best describes a key difference between Model 1 and Model 2 regarding how energy is released to heat the corona?