All practice questions

Read the sentence below. To maintain a consistent grammatical construction and avoid an incorrect shift in verb tense, which form of the verb 'freeze' should be written in the blank?

The passage below describes subterranean fungal networks in forests. Read the passage and identify the correct present-tense forms of the verbs 'to be' (for the first blank) and 'to depend' (for the second blank) that maintain proper subject-verb agreement. What are the correct verb forms to fill in the blanks?

The young eagle spread it's wings and soared high above the canyon walls.

Which choice is the correct spelling for the underlined word in the context of this sentence?

### Models of the Moon's Origin

The origin of Earth’s Moon remains a fundamental question in planetary science. Scientists have proposed several models to explain the Moon's physical and chemical properties, including its low density, small iron core, and identical oxygen isotope ratios compared to Earth.

*Model 1 (Fission Model)*
This model proposes that the Moon was once part of the Earth but was spun off from a rapidly rotating, molten proto-Earth early in its history. Centrifugal forces caused material from Earth's outer mantle to separate and form the Moon. Because the Moon formed from Earth’s mantle, it would naturally have a low density and low iron content, explaining the similarity in oxygen isotope ratios. However, this model predicts that the Earth-Moon system would possess much more angular momentum than is currently observed.

*Model 2 (Capture Model)*
This model proposes that the Moon formed independently in another region of the solar nebula and was later gravitationally captured during a close flyby of Earth. While this model easily explains why the Moon has a different internal composition and a smaller relative core size than Earth, it requires an extremely unlikely orbital trajectory and a dissipative mechanism (such as atmospheric drag or tidal forces) to slow the Moon down enough to enter a stable orbit rather than escaping. It also fails to explain why Earth and Moon rocks share identical isotopic signatures.

*Model 3 (Giant Impact Model)*
This model proposes that a Mars-sized protoplanet collided with the young Earth. The high-energy collision vaporized the impactor and part of Earth's mantle, ejecting a disk of superheated debris into orbit. This debris eventually accreted to form the Moon. Because the debris consisted primarily of silicate mantles rather than metallic cores, the resulting Moon was iron-poor. The intense mixing during the collision explains the identical oxygen isotope ratios, and the collision dynamics account for the current angular momentum of the system.

Based on the descriptions provided, match each model of the Moon's origin with the characteristic or constraint that uniquely applies to it.

After descending thousands of feet into the ocean's abyssal zone, the scientists' remote camera captured a previously unknown species of bioluminescent jellyfish.

Which of the following choices, if substituted for the underlined portion, makes the sentence grammatically correct?

Carefully scraping away layers of yellowed varnish, the vibrant original colors of the portrait were revealed by the art conservator. The painting, which had been hidden for over a century, once again looked as the artist intended. Visitors to the museum can now appreciate its true beauty.

Which of the following choices best replaces the underlined portion of the sentence to ensure that the sentence is grammatically correct and logically structured?

Read the following passage and answer the question that follows.

In the late nineteenth century, botanist Elizabeth Gertrude Britton and her husband Nathaniel Lord Britton worked tirelessly to establish the New York Botanical Garden. Elizabeth wrote hundreds of articles on mosses while Nathaniel organized the institutional funding, which ensured that <u>it</u> would become a premier research facility.

Which choice is the best replacement for the underlined word to ensure that the sentence is clear and grammatically correct?

### Heating the Solar Corona

The Sun’s outer atmosphere, the corona, has a temperature of over $1 \times 10^6\text{ K}$, which is far hotter than the Sun's surface (the photosphere) at approximately $5,800\text{ K}$. Scientists have proposed two hypotheses to explain how energy is transported from the surface to heat the corona.

Hypothesis 1
Energy is transported by Alfvén waves (oscillating magnetic waves) that originate at the photosphere. These waves travel along magnetic field lines up into the corona, where they dissipate their energy as heat into the surrounding plasma.

Hypothesis 2
Energy is transported by nanoflares (small-scale magnetic reconnection events). As magnetic field lines in the corona twist and cross due to surface motions, they suddenly snap and realign. This process releases stored magnetic energy in rapid, localized bursts that heat the corona.

New Evidence
Researchers measure the wave energy of Alfvén waves at different heights above the solar surface and find that these waves lose nearly all of their energy in the chromosphere (the layer between the photosphere and the corona), long before reaching the corona.

Which of the following statements best describes how this new evidence affects the two hypotheses?

During the final phase of testing, the engineering team monitored the prototype's performance in a soundproof chamber. Although the new engine was expected to run loudly, it actually operated much more quieter than its predecessor. This noise reduction was attributed to the newly designed exhaust valves.

Which choice best corrects the underlined portion of the sentence?

During the excavation of the ancient Roman villa, the archaeologists uncovered a cache of beautifully preserved glass vessels. Because the glass had become extremely brittle over the centuries, the researchers had to handle each piece with extreme care. They worked at their exceptionally slow pace, carefully documenting the coordinates of each find before lifting it from the soil.

Which of the following choices best replaces the underlined portion to ensure the sentence is grammatically correct?

In 1967, astrophysicist Jocelyn Bell Burnell noticed a series of anomalies in the data from a newly constructed radio telescope. While analyzing the chart recorder prints, she observed a tiny, repeating signal that pulsed with remarkable regularity. Although some of her colleagues initially dismissed the pulses as man-made interference, Bell Burnell remained convinced of their extraterrestrial origin. Her persistent investigation eventually leads to the discovery of pulsars, rapidly rotating neutron stars that emit beams of electromagnetic radiation. Today, astronomers use these celestial objects as precise cosmic clocks to study gravitational waves.

Which choice, if any, is the most appropriate replacement for the underlined word?

Fill in the blanks in the sentence below with the correct words from the frequently confused pair 'accept' and 'except'.

Based on the context of the passage about Virginia Woolf's novel, what are the correct forms of the verbs 'compose' and 'unfold' that should fill in the blanks to maintain grammatical consistency and appropriate verb tense?

Passage

Early sound recordings from the late nineteenth century were captured on fragile wax cylinders, which degrade rapidly when exposed to heat and humidity. Consequently, researchers at the Library of Congress have developed non-contact optical scanning technology to digitize these delicate artifacts. This method uses light to read the physical grooves without touching the wax, preserving the audio before the cylinders deteriorate completely.

Question
Which of the following options best maintains the logical flow and correct punctuation of the passage?

To investigate the factors affecting the rate of transpiration in plants, students set up two distinct experiments using identical bean plants.

In Experiment 1, three plants were placed in separate chambers with varying levels of relative humidity ($30\%$, $50\%$, and $70\%$) at a constant temperature of $22^\circ\text{C}$ and a constant light intensity of $800\text{ lux}$. The mass of water lost by each plant was measured after 6 hours.

In Experiment 2, three plants were placed in separate chambers at varying temperatures ($18^\circ\text{C}$, $24^\circ\text{C}$, and $30^\circ\text{C}$) at a constant relative humidity of $50\%$ and a constant light intensity of $800\text{ lux}$. The mass of water lost by each plant was measured after 6 hours.

Determine whether the following statement is true or false:

The relative humidity of the environment in Experiment 2 was held constant at a value that was also tested as an experimental condition in Experiment 1.

How should the following segments be ordered to construct a clear, grammatically correct sentence that avoids misplaced modifiers?

Although electric eels are famous for their ability to generate strong electrical discharges, they use these pulses primarily for navigation. In the murky waters of the Amazon Basin, an eel emits weak electrical signals to scan its surroundings. After these signals bounced off nearby objects, the eel's specialized receptors detect the returning current to map the environment.

Which choice most effectively maintains a consistent grammatical construction and tense throughout the sentence?

### Models of the Cryogenian Glaciations

During the Cryogenian period (approximately 720 to 635 million years ago), Earth experienced widespread, severe glaciations. Geologists have proposed two models to explain the extent of the ice coverage.

Model 1 (Hard Snowball Earth)
This model asserts that glaciers reached the equator, and the entire surface of Earth's oceans was completely frozen over with ice sheets up to 1 kilometer thick. This global ice cover decoupled the oceans from the atmosphere, halting the hydrological cycle (evaporation and precipitation) and severely restricting photosynthesis due to the lack of sunlight penetrating the thick ice. According to Model 1, the glaciation ended only when carbon dioxide ($CO_2$) released by volcanic outgassing accumulated in the atmosphere to extremely high levels (approximately 350 times modern levels), creating a massive greenhouse effect that rapidly melted the ice.

Model 2 (Slushball Earth)
This model asserts that while glaciers were widespread at high and middle latitudes, Earth was not completely frozen. A band of open water, or extremely thin sea ice, persisted around the equator. As a result, the hydrological cycle continued to function, albeit at a reduced rate. Marine photosynthetic microorganisms survived in these open equatorial waters. According to Model 2, the accumulation of $CO_2$ from volcanic outgassing was also responsible for ending the glaciation, but the required concentration of $CO_2$ to initiate melting was significantly lower because the albedo (reflectivity) of open water is much lower than that of solid ice.

Based on the passage, Model 1 and Model 2 agree on which of the following aspects of the Cryogenian glaciations?

The following passage contains a blank. Which form of the verb 'document' should fill the blank to maintain a consistent grammatical construction and avoid an inappropriate shift in verb tense?

### Heat Sources of Enceladus' Ocean

Enceladus, a small icy moon of Saturn, possesses a global subsurface liquid water ocean beneath its icy crust. Scientists debate the primary mechanism responsible for generating the heat necessary to maintain this liquid ocean.

Hypothesis 1
The ocean is kept warm primarily by *tidal dissipation*. As Enceladus orbits Saturn, gravitational forces from Saturn and neighboring moons continuously flex Enceladus’s porous, rocky core. This flexing creates frictional heating in the rock, which directly warms the water circulating through the core. This mechanism is highly dynamic, concentrating heat generation in active zones and producing localized hydrothermal temperatures exceeding $100^\circ\text{C}$.

Hypothesis 2
The ocean is kept warm primarily by *radiogenic heating*. The rocky core of Enceladus contains unstable radioactive isotopes, such as potassium-40 ($^{40}\text{K}$) and uranium-235 ($^{235}\text{U}$). The decay of these isotopes releases a steady flow of thermal energy. Because the isotopes are uniformly distributed throughout the core, this decay produces a gentle, uniform warmth, with maximum core temperatures reaching no higher than $30^\circ\text{C}$.

New Evidence
Astronomers analyzing data from a space probe detect nanometer-sized silica ($\text{SiO}_2$) particles in the plumes of vapor erupting from Enceladus’s southern polar crust. Laboratory experiments show that these specific nanometer-sized silica particles can only form when mineral-rich water is heated to temperatures above $90^\circ\text{C}$ and subsequently mixed with cold water.

Based on this information, how does the detection of the nanometer-sized silica particles in Enceladus's plumes affect the two hypotheses?