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In the late 1960s, marine biologist Sylvia Earle led the Tektite II project, an all-female research expedition that lived in an underwater habitat for two weeks. Because the mission was designed to study marine life and test the effects of isolation. The scientists successfully conducted their research and garnered international acclaim.
Which choice best corrects the underlined portion of the sentence?
Although the lead scientist preferred to run the experiment using a new set of variables, the lab director insisted in adhering to the original protocol.
Which choice best replaces the underlined portion of the sentence?
During a laboratory investigation on acoustics, researchers recorded the characteristics of sound waves traveling through a gas chamber at a constant temperature. For each trial, the wave's wavelength (, measured in meters) and its frequency (, measured in hertz) were documented in the table below.
| Trial | Wavelength () | Frequency () |
|---|---|---|
| 1 | ||
| 2 | ||
| 3 | ||
| 4 |
According to the data, as the wavelength of the sound waves decreases, the frequency of the sound waves:
Two scientists debate the formation of the Grand Canyon.
Scientist 1
The Grand Canyon was carved slowly over approximately 6 million years. The Colorado River gradually eroded the uplifting Colorado Plateau. The erosion rate remained relatively constant, averaging about . This slow process allowed the river to gradually cut through the rising rock strata, depositing fine, well-sorted sediments downstream at a steady rate.
Scientist 2
The Grand Canyon was formed rapidly, likely within a few weeks, by a catastrophic outburst flood. Approximately 5.5 million years ago, a massive prehistoric lake located on the Colorado Plateau breached its natural barrier. The sudden release of water created a massive, high-velocity flow that carved the canyon. This flood would have deposited a thick layer of unsorted gravel and large boulders downstream.
Based on the presented viewpoints, the discovery of a downstream sediment layer containing large, poorly sorted boulders dated to 5.5 million years ago is consistent with the predictions of Scientist 1.
For decades, the geological origins of the massive sarsen stones at Stonehenge remained a mystery to archaeologists. However, a recent chemical analysis has finally revealed the source where the stones originally came from. Which choice is the best replacement for the underlined portion?
Working in a high-temperature studio, the glassblower gathered a molten glob of glass on the end of a steel blowpipe. He continuously rolled the pipe to maintain a spherical shape, and then he blows gently into the tube to expand the glass bubble.
Which choice best corrects the underlined portion to ensure the sentence maintains a consistent verb tense?
### Hawaiian-Emperor Seamount Chain
The Hawaiian-Emperor seamount chain is a trail of volcanoes on the Pacific Plate. Two hypotheses discuss the origin of these volcanoes.
Hypothesis 1 (Stationary Plume)
A stationary mantle plume under the Pacific Plate supplies magma. As the plate moves northwestward at a constant rate, new volcanoes form directly over the plume. Volcanoes that have moved away from the plume become inactive. This hypothesis predicts that the age of the seamounts increases linearly with distance from the active hotspot ( at Hawaii).
Hypothesis 2 (Lithospheric Stress)
Volcanism occurs along pre-existing fractures in the plate. The fractures open due to tectonic stress changes at plate boundaries. Volcanic activity can occur simultaneously along a fracture zone, and the age of volcanic centers is determined by when stress reactivation occurred, resulting in clustered or non-linear ages along the chain.
Researchers measured the age and distance from Hawaii of four seamounts in the chain, shown in the table below:
| Seamount | Distance from Hawaii (km) | Measured Age (million years) |
|---|---|---|
| Seamount W | 500 | 5.2 |
| Seamount X | 1,000 | 9.8 |
| Seamount Y | 1,500 | 15.1 |
| Seamount Z | 2,000 | 19.9 |
Which hypothesis is supported by this data, and why?
The chef spent hours preparing the signature soup, he added a secret blend of herbs right before serving.
Which choice is the best version of the underlined portion?
The passage below contains two blanks. Fill in each blank with the correct phrase from the choices provided to ensure the passage is grammatically correct and free of misplaced or dangling modifiers.
For blank 1, choose and type exactly one of the following:
* the city council renovated the historic theater
* the historic theater was renovated by the city council
For blank 2, choose and type exactly one of the following:
* which was designed in the 1920s and now shines brightly over the plaza
* which now shines brightly over the plaza designed in the 1920s
Fill in the blanks below
A scientist records the daily growth of a plant in millimeters over 5 days in the table below:
| Day | Growth (mm) |
|---|---|
| Monday | 6 |
| Tuesday | 12 |
| Wednesday | 4 |
| Thursday | 11 |
| Friday | 7 |
What is the median daily growth, in millimeters, of the plant over these 5 days?
In 1964, the research submersible *Alvin* was commissioned, allowing scientists to explore the deep ocean floor. Previously before this time, marine biologists relied on indirect measurements; they had no way to observe the abyss directly.
Which of the following is the best version of the underlined portion of the sentence?
An online streaming service charges a flat monthly subscription fee of plus for each premium movie rented. The total monthly cost, in dollars, for a user who rents premium movies is represented by the expression . What is the total monthly cost, in dollars, for a user who rents premium movies?
Every autumn, millions of monarch butterflies embark on a perilous journey from North America to the forests of central Mexico. This annual migration occurs on a yearly basis, it is essential for their survival during the cold winter months.
Which of the following alternatives to the underlined portion is the most appropriate?
Read the passage below. To ensure that the introductory phrase logically modifies the subject of the sentence, which researcher's name should be placed in the blank?
Fill in the blanks below
An online bookstore sells paperback novels for dollars each. The total cost, in dollars, to purchase novels and have them shipped to a customer's home is given by the expression . What is the total cost, in dollars, to purchase novels and have them shipped?
A technology company has three departments: Sales, Marketing, and Engineering. The table below shows the number of employees in the Sales and Marketing departments, along with the mean annual salary for each of the three departments.
| Department | Number of Employees | Mean Annual Salary |
|---|---|---|
| Sales | ||
| Marketing | ||
| Engineering |
If the mean annual salary of all employees across all three departments is , what is the total number of employees in the company?
The following passage is adapted from an essay on early twentieth-century particle physics and atmospheric radiation research.
In the late nineteenth century, physicists observed that electroscopes—instruments designed to detect electrical charge—ineplicably leaked charge over time, even when meticulously insulated. Early hypotheses attributed this spontaneous ionization of air inside the electroscopes primarily to trace amounts of radioactive elements present in the Earth’s crust. If terrestrial rocks were the sole source of this penetrating radiation, ionization rates ought to decrease exponentially with increasing altitude as distance from the ground expanded.
To test this assumption, German physicist Theodor Wulf constructed an enhanced, highly sensitive double-vane electrometer encased in a sealed zinc vessel. In 1910, Wulf carried his instrument to the top of the Eiffel Tower, approximately 300 meters above Paris, expecting to measure a dramatic reduction in radiation intensity compared to ground level. However, his measurements revealed that radiation levels at the summit dropped to roughly half of their ground values—a far slower decline than the theoretical model predicted for purely terrestrial origins. Despite Wulf’s rigorous calibration, many contemporaries dismissed his findings as an anomaly caused by residual radioactive contamination embedded within the tower's iron lattice or ambient atmospheric dust.
Seeking definitive empirical clarity, Austrian physicist Victor Hess designed a series of ten daring high-altitude free-balloon ascents between 1911 and 1912. Hess modified Wulf’s sealed electrometer design, equipping his balloon gondola with multiple thick-walled brass electroscopes capable of withstanding extreme variations in ambient atmospheric pressure and temperature. Furthermore, Hess employed two distinct types of instruments simultaneously: one with thin walls to record total ionization and another with heavy temperature-compensated walls to filter out soft, low-energy background radiation. During his famous seventh flight on August 7, 1912, Hess aboard the balloon *Böhmen* reached an unprecedented altitude of 5,350 meters without supplemental oxygen.
Hess’s meticulous data recorded a subtle initial drop in ionization up to an altitude of approximately 1,000 meters. Beyond this threshold, however, ionization rates reversed course, rising steadily. By the time *Böhmen* attained 5,350 meters, the measured radiation rate was nearly four times greater than that observed at sea level. To rule out the Sun as the primary source of this high-energy radiation, Hess performed an ascent during the near-total solar eclipse of April 17, 1912. Because the radiation intensity remained unchanged while the moon obscured the solar disk, Hess concluded that the Sun itself could not be the main generator of these rays. Instead, he asserted that a tremendously penetrating radiation must be entering the Earth's atmosphere from deep outer space—a phenomenon later named 'cosmic rays' by Robert Millikan.
Based on the passage, determine whether the following statement is True or False:
During his 1912 balloon flights, Victor Hess used identical thin-walled electroscopes in order to measure total atmospheric radiation levels without filtering low-energy background noise.
The following passage is adapted from an essay on early twentieth-century particle physics and atmospheric science:
In the early years of the twentieth century, physicists were puzzled by the spontaneous discharge of electroscopes, sensitive instruments used to detect electrical charge. Most scientists hypothesized that this background ionization of the atmosphere was caused entirely by natural gamma radiation emitted from radioactive minerals in the Earth's crust. Under this terrestrial model, atmospheric ionization was expected to diminish rapidly with increasing distance from the ground.
To test this assumption, Austrian physicist Victor Francis Hess conducted a series of ten daring balloon ascents between 1911 and 1912. On his final and most decisive flight, on August 7, 1912, Hess boarded a hydrogen-filled balloon named *Böhmen*, accompanied by two navigators. Carrying three specially reinforced, temperature-compensated Wulf electroscopes—two designed to measure total radiation and one unsealed to measure atmospheric pressure—Hess ascended to an altitude of 5,350 meters above the Bohemian landscape.
Hess recorded meticulous observations at regular altitude increments throughout the six-hour voyage. Below 1,000 meters, his electroscopes indeed indicated a slight drop in ionization rates compared to ground level, consistent with the terrestrial radiation model. However, as the balloon rose past 1,800 meters, the ionization level unexpectedly began to climb. By the time Hess reached 5,350 meters, the measured ionization rate was more than double the rate recorded at sea level.
Crucially, Hess had timed the flight to coincide with a partial solar eclipse. Because the solar disk was largely covered during the ascent, Hess was able to rule out the Sun as the primary immediate source of the radiation. Based on these observations, Hess concluded that a highly penetrating radiation must be entering the Earth's atmosphere from outer space—a discovery of extra-terrestrial radiation later termed "cosmic rays" by Robert Millikan, for which Hess was awarded the Nobel Prize in Physics in 1936.
Based on the passage, evaluate whether the following statement is True or False:
During his August 7, 1912 flight aboard the balloon *Böhmen*, Victor Hess observed that atmospheric ionization rates decreased continuously as altitude increased up to his peak height of 5,350 meters.
A coastal lighthouse beacon rotates through a central angle of , sweeping across a circular sector of sea with a radius of . What is the total perimeter, in nautical miles, of the region swept by the beacon?
Passage A
During the late nineteenth century, oceanography relied almost exclusively on mechanical wire sounding to estimate ocean depths. Pioneer expeditions, most notably that of the HMS Challenger (1872–1876), lowered weighted hemp lines and later steel piano wire to measure discrete points along transatlantic traverses. Scientists recorded depths by measuring the length of wire unspooled before bottom impact was detected. Because sounding a single point required stopping the vessel for hours and unspooling thousands of meters of line, data points were separated by dozens or even hundreds of nautical miles.
Interpolating between these sparse data points naturally smoothed out topographical variations. Oceanographers concluded that the seabed consisted primarily of featureless abyssal plains—immense, sediment-covered basins devoid of significant relief. Prominent geological features were assumed to be isolated volcanic islands rising sharply from flat sea floors rather than continuous mountain chains. While wire sounding successfully disproved the long-held myth that the deep ocean was bottomless, its methodological sampling limitations unwittingly fostered a conceptual paradigm of marine topography as fundamentally quiescent and flat.
Passage B
The introduction of acoustic echo sounding in the 1920s transformed marine geophysics by substituting mechanical lines with sound waves. By emitting ultrasonic pulses and recording the precise travel time required for the sound waves to bounce off the seafloor and return to the surface, echo sounders enabled moving vessels to collect continuous profiles of oceanic depth.
When the German Research Vessel Meteor surveyed the South Atlantic between 1925 and 1927, acoustic profiles revealed a startlingly dynamic underwater landscape. Rather than a flat, featureless abyssal plain, the bathymetric data demonstrated that the ocean floor was bisected by an enormous, rugged underwater ridge system. Continuous acoustic data captured steep slopes, sharp peaks, and deep axial rift valleys that had escaped detection during sparse wire-sounding surveys. The data synthesized by Meteor researchers demonstrated that oceanic bathymetry was structurally complex and geologically active.
Subsequent synthesis of cross-passage evidence shows how technological shifts alter scientific models. Where mechanical sounding provided static, localized data points that led researchers to infer vast topographic uniformity, continuous acoustic sounding supplied dense spatial data revealing extensive tectonic structures. Echo sounding did not merely refine previous measurements; it overturned the foundational assumption of abyssal flatness, establishing that ocean basins contain active geological features comparable in scale to continental mountain ranges.
Based on both passages, how does the evidence gathered by acoustic echo sounding (Passage B) most directly challenge the main conclusions drawn from wire sounding data (Passage A)?