All practice questions

To ensure proper grammatical structure and tense consistency throughout the passage, which verb forms of 'perform' and 'deviate' should be used to fill in the blanks?

Astronomers debate the origin of High-Velocity Clouds (HVCs)—large clouds of gas moving through the Milky Way’s halo.

Viewpoint 1
HVCs are part of a 'galactic fountain.' Supernova explosions in the galactic disk heat gas and eject it upward into the halo. As this gas cools, it condenses and falls back toward the disk. Because this gas originates from the disk, it must have a high abundance of heavy elements (high metallicity) and contain dust particles typical of the disk.

Viewpoint 2
HVCs are primordial intergalactic gas clouds being accreted (pulled in) by the Milky Way's gravity. This gas is falling into the galaxy for the first time. Therefore, it should have an extremely low abundance of heavy elements (low metallicity) and contain virtually no dust, reflecting the composition of undeveloped space.

Match each hypothetical observation of a High-Velocity Cloud (HVC) to the viewpoint it supports or aligns with.

Because a volcanic eruption was eminent, scientists closely monitored the seismic activity and urged local authorities to prepare evacuation routes.

Which choice is the correct word to use in the underlined portion of the sentence?

Passage

Below a depth of about 150 meters, the Black Sea contains virtually no oxygen, which prevents the survival of wood-boring organisms that normally consume sunken vessels. Consequently, hulls, masts, and even delicate ropes remain intact after centuries underwater.

Which choice provides the most logical transition from the preceding sentence to the sentence that follows while maintaining correct sentence structure?

Read the passage below. To ensure the sentence is grammatically correct and avoids misplaced or dangling modifiers, which of the following phrases should be used to fill in the blank?

Choices:
- 'the researchers discovered a cluster of glowing mycelium'
- 'a cluster of glowing mycelium was discovered by the researchers'
- 'the researchers, who was searching for new species, discovered a cluster of glowing mycelium'
- 'which allowed the researchers to discover a cluster of glowing mycelium'

While cataloging the fragments of the newly unearthed clay tablets, the ancient script was finally deciphered by the linguist using a comparative database. This breakthrough shed light on the economic transactions of the early Bronze Age. Consequently, historians have had to revise their theories regarding regional trade networks.

Which of the following options, if substituted for the underlined portion of the passage, produces a sentence that is grammatically correct and logically coherent?

The following sentence contains an underlined word.

After hours of debate, the city counsel voted to approve the new environmental regulations for the construction of the downtown park.

Which choice is the correct word to use in the underlined portion of the sentence?

To monitor the structural integrity of the bridge, the engineers measured the vibrations of the steel cables. The newly installed sensors detected the frequency shifts more precise than the older analog devices did, providing the team with highly accurate data.

Which choice best replaces the underlined portion to ensure correct grammatical usage?

Read the sentence below. Which form of the verb in parentheses correctly completes the sentence to maintain proper subject-verb agreement?

### Hypotheses on the Origin of Life

#### Model 1 (RNA World Hypothesis)
The RNA World hypothesis proposes that self-replicating ribonucleic acid (RNA) molecules were the precursors to modern life. In this model, RNA served both as the genetic material (storing information) and as a catalyst for chemical reactions (similar to modern protein enzymes called ribozymes). Over time, DNA took over the role of genetic storage due to its greater chemical stability, and proteins became the primary catalysts because of their greater chemical versatility. RNA-based systems evolved in prebiotic aqueous environments rich in nucleotides, requiring external energy sources such as ultraviolet (UV) radiation from the Sun to drive the synthesis of nucleotides and other organic compounds.

#### Model 2 (Iron-Sulfur World Hypothesis)
The Iron-Sulfur World hypothesis proposes that life originated near deep-sea hydrothermal vents. According to this metabolism-first model, the earliest life-like systems were mineral-based metabolic networks that did not rely on self-replicating genetic polymers initially. Instead, geochemical energy—specifically, the temperature and chemical gradients of hot, mineral-rich hydrothermal fluids containing hydrogen sulfide ($H_2S$) and dissolved iron—drove the synthesis of organic molecules. Iron-sulfur minerals catalyzed the reduction of carbon dioxide ($CO_2$) into organic molecules through a primitive, non-enzymatic cycle. Genetic systems like RNA and DNA evolved later as late additions to stabilize these existing metabolic pathways.

Based on the models described, match each prebiotic feature or energy source on the left with the correct model classification on the right.

For centuries, cartographers faced the daunting task of mapping uncharted territories using only basic tools like astrolabes and compasses. They spent months at sea, documented coastline features with painstaking precision, and would gather stories from local merchants to fill in geographic gaps. Despite these limitations, their maps remained remarkably accurate for the era.

Which of the following choices to the underlined portion is most grammatically correct and consistent with the rest of the passage?

A group of students conducted an experiment to study the relationship between the pressure and volume of a gas sample at a constant temperature. The gas was contained in a cylinder equipped with a movable piston. By adjusting the piston, the students varied the volume of the gas ($V$, in liters) and measured the resulting pressure ($P$, in atmospheres). The results are recorded in the table below.

If the students perform a fifth trial and adjust the piston to a volume of $4.0\text{ L}$, which of the following is the most likely pressure of the gas sample?

During the kitchen inspection, the health inspector reminded the restaurant manager and he that their sanitizing protocols must be updated immediately.

Which of the following options is the best replacement for the underlined portion of the sentence?

Complete the passage by entering the correct grammatical forms of the modifiers in parentheses (use 'beautiful' for the first blank and 'harsh' for the second blank).

Peat bogs play a critical role in regulating the Earth's climate by storing vast amounts of carbon; these damp, wet peatlands contain more carbon than all of the world's forests combined.

Which choice most effectively eliminates the redundancy in the underlined portion of the sentence?

While hiking through the dense canopy of the Ecuadorian rainforest, a rare orchid was discovered by the botanist that had never been documented before.

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

### Models of the Formation of Saturn's Rings

Saturn's prominent ring system consists primarily of water ice ($H_2O$) with trace amounts of rocky material and organic compounds. Geochemists and astrophysicists have proposed different models to explain the origin of these rings.

Model 1 (Tidal Disruption Model)
According to this model, about $100$ million years ago, a mid-sized, icy satellite (moon) with a rocky core migrated inward toward Saturn due to orbital resonances. As the satellite crossed Saturn's Roche limit (approximately $140,000\text{ km}$ from the center of Saturn), Saturn's gravitational tidal forces overcame the satellite's self-gravity. The outer icy mantle of the satellite was stripped away and spread into a disk, while the denser rocky core spiraled into Saturn. This model predicts that the rings are relatively young (less than $100$ million years old) and consist of highly pure ice because the rocky core was segregated and lost.

Model 2 (Collisional Shattering Model)
According to this model, Saturn's rings are ancient structures formed over $4$ billion years ago during the Late Heavy Bombardment. A population of large, organic-rich comets from the outer solar system was gravitationally pulled toward Saturn. Several of these comets collided at high velocities with pre-existing inner moons of Saturn. The energy of these impacts shattered both the comets and the moons, distributing the fragments into orbit. Because comets and ancient moons contain significant amounts of rocky silicates and complex organic compounds, the primordial ring material originally had a higher concentration of non-ice components, which have since been slowly eroded by micrometeorite bombardment.

Based on the models presented, match each physical description or formation scenario of Saturn's rings to the correct model or models.

To ensure that the introductory phrase modifies the correct subject, which of the two phrases—'the conservation team' or 'the Renaissance fresco'—should be placed in the blank to complete the sentence?

### The Formation of the Asteroid Belt

The asteroid belt, located between Mars and Jupiter, contains millions of rocky and metallic bodies. However, its total mass is only about $0.05\%$ of Earth's mass. Astronomers have proposed competing models to explain the origin and low mass of the asteroid belt.

#### Model 1 (The Grand Tack Model)
Model 1 proposes that the asteroid belt region initially contained a high density of planetesimals, totaling several Earth masses. Shortly after its formation, Jupiter migrated inward from its birth orbit toward the Sun, reaching a distance of $1.5\text{ AU}$ (near Mars's current orbit). As Jupiter migrated, its strong gravitational influence scattered approximately $99.9\%$ of the planetesimals out of the region. Jupiter then migrated back outward to its current orbit. The remaining $0.1\%$ of the original planetesimals, along with some outer solar system material swept up during Jupiter's return, formed the current asteroid belt.

#### Model 2 (The Low-Mass Disk Model)
Model 2 proposes that the region of the asteroid belt was initially almost empty, containing very little mass due to a physical gap in the early protoplanetary dust disk. As the terrestrial planets (such as Earth and Mars) and the giant planets (such as Jupiter and Saturn) grew, their gravitational interactions scattered nearby leftover planetesimals. Some planetesimals from the inner solar system (silicate-rich) and others from the outer solar system (carbon-rich) were thrown into the gap. These scattered bodies became gravitationally trapped in stable orbits, creating the modern asteroid belt. In Model 2, the giant planets did not undergo large-scale orbital migrations through the inner solar system.

According to the models, which of the following statements describes an assumption about the initial mass of the asteroid belt region that is made by Model 1 but NOT by Model 2?

The following sentence contains two blanks where a pair of frequently confused words—'precede' and 'proceed'—should be placed. Which word choices correctly complete the blanks in the sentence based on their context?