All practice questions

Read the passage below about cognitive neuroscience. Fill in the blank with the correct present-tense form of the verb 'suggest' that agrees with the subject of the sentence.

In 1964, radio astronomers Arno Penzias and Robert Wilson detected a persistent background hiss in their Holmdel horn antenna. They meticulously cleaned the equipment and even removed nesting pigeons, nevertheless, the noise remained.

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

In the sentence below, a portion of the text is underlined.

Though initially dismissed as mere decorative patterns by early explorers, Yuri Knorozov eventually deciphered the Mayan glyphs in the mid-twentieth century.

Which of the following choices represents the most effective and grammatically correct version of the underlined portion?

Archaeologists studying the ancient Andean temple complex at Chavín de Huántar have discovered that its subterranean galleries function as acoustic resonators. Because the stone conduits project and amplify the sound of shell trumpets. The design of the labyrinth suggests that the builders intended to disorient and awe initiates during ceremonies.

Which of the following options best corrects the underlined portion to make the sentence grammatically correct?

The Aztecs developed a unique agricultural method known as chinampas to sustain their growing population in the Valley of Mexico. These raised gardens were constructed by layering mud, lake sediment, and decaying vegetation within shallow lake beds. Willow trees were planted along the borders of these rectangular plots, their roots anchored the soil and prevented erosion.

Which choice best corrects the underlined portion of the passage?

The sentence below describes the primary responsibilities of a marine biologist on a research vessel. Complete the sentence by writing the correct form of the verb 'record' in the blank to maintain parallel structure.

Although marine biologists have long studied the complex vocalizations of humpback whales, their understanding of the social structure of these pods is still in its infancy. Because these animals often travel thousands of miles through open ocean, which makes long-term observation incredibly difficult.

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

During a laboratory study on cellular respiration, a researcher measures the oxygen consumption rate of a single isolated mitochondrion. The mitochondrion consumes $3.5 \times 10^{-15}\text{ moles}$ of oxygen gas ($\text{O}_2$) per second. To compare this with macro-scale metabolic rates, the researcher needs to express this value in picomoles ($\text{pmol}$) per hour. Which of the following is closest to the oxygen consumption rate of the mitochondrion in $\text{pmol/hour}$?

The architectural firm's proposal for the new community center focused on maximizing natural light, minimizing environmental impact, and to integrate local materials into the design.

Which choice best maintains parallel structure in the sentence?

The Faint Young Sun Paradox

Standard astrophysical models indicate that during the Archean eon ($3.8$ to $2.5$ billion years ago), the Sun's energy output was only about $70\%$ to $75\%$ of its current value. Under these conditions, Earth's surface temperature should have been well below freezing, yet geological evidence confirms the continuous presence of liquid water oceans. Two models attempt to explain this paradox.

*Model 1*
Early Earth's atmosphere contained significantly higher concentrations of greenhouse gases, primarily carbon dioxide ($CO_2$) and methane ($CH_4$), than it does today. Active volcanism continuously released large quantities of $CO_2$ into the atmosphere. Additionally, because continental landmasses were small, the rate of silicate weathering (a chemical process that removes atmospheric $CO_2$ and stores it in crustal rocks) was extremely low. The abundance of these gases trapped outgoing infrared radiation, maintaining surface temperatures above freezing.

*Model 2*
The primary driver of early Earth's warmth was a lower planetary albedo (reflectivity), which allowed the Earth to absorb a larger fraction of the Sun's incoming radiation. During the Archean eon, continental landmasses occupied less than $5\%$ of Earth's surface, leaving the planet dominated by dark oceans that absorbed solar energy. Furthermore, the absence of land plants and certain marine organisms meant there were fewer biogenic aerosols to act as cloud condensation nuclei. This resulted in fewer, thinner clouds, allowing more solar radiation to reach and warm the surface.

Based on Model 2, which of the following statements best describes the hypothesis explaining how early Earth maintained liquid water?

When the curation team placed the antique vase next to the marble bust, [it] immediately drew the attention of the museum visitors. Its intricate gold engravings glinted under the gallery lights. Many guests stopped to admire the craftsmanship.

Which choice best clarifies the reference of the underlined pronoun?

A student measured the speed of sound in a chamber filled with pure carbon dioxide ($CO_2$) gas at various temperatures. The measured speed of sound, in meters per second ($\text{m/s}$), at each temperature, in degrees Celsius ($^\circ\text{C}$), is shown in the table below:

Assuming the speed of sound continues to change at a constant rate with respect to temperature, what is the predicted speed of sound in $CO_2$ gas, in meters per second ($\text{m/s}$), at a temperature of $100^\circ\text{C}$?

An investigation is designed to examine the reaction rate between magnesium ($\\text{Mg}$) and hydrochloric acid ($\\text{HCl}$). In the baseline trial, a single $2.0\\text{ g}$ solid strip of $\\text{Mg}$ is placed into $100\\text{ mL}$ of $1.0\\text{ M}$ $\\text{HCl}$ solution at 22^\\circ\\text{C}, and the volume of hydrogen gas ($\\text{H}_2$) released is recorded over $5\\text{ minutes}$.

To isolate the effect of reactant surface area on the reaction rate, a second trial must be designed. Which of the following experimental setups would allow for a valid comparison to the baseline trial?

During the construction of the Brooklyn Bridge, chief engineer Washington Roebling fell severely ill and was confined to his home. His wife, Emily Warren Roebling, stepped in to manage the daily operations, teaching herself civil engineering and materials science. She acted as a liaison, conveying detailed technical instructions between Washington and the assistant builders, which enabled [them] to complete the massive suspension bridge.

Which choice is the most effective replacement for the underlined portion to ensure pronoun clarity and precise reference?

In 2004, atmospheric methane ($CH_4$) was detected on Mars. Because methane is rapidly destroyed by solar ultraviolet radiation in the Martian atmosphere, its ongoing presence implies an active source. Two scientists discuss whether this methane has a biological or non-biological origin.

Scientist 1
The atmospheric methane on Mars is produced by subterranean methanogenic microbes. These microbes reside deep underground where liquid water is present and geothermal heat provides a stable environment. They metabolize carbon dioxide ($CO_2$) and hydrogen ($H_2$) to produce methane. The seasonal fluctuations in atmospheric methane levels observed by orbiters are due to changes in microbial metabolic activity; as subterranean temperatures rise during the Martian summer, the microbes become more active and produce more methane, which then diffuses to the surface.

Scientist 2
The atmospheric methane on Mars is abiotic, produced by serpentinization—a chemical reaction between water, dissolved carbon dioxide, and olivine-rich rocks in the Martian crust. This reaction occurs deep underground at high temperatures. The methane is stored in subsurface ice cages called clathrates. The seasonal fluctuations in atmospheric methane levels are not caused by changes in the rate of methane production, but rather by the seasonal melting of surface ice seals. During the Martian summer, increased solar radiation warms the surface, cracking the ice seals and allowing trapped methane to escape into the atmosphere.

Scientist 1 and Scientist 2 differ in their views regarding which of the following aspects of Martian methane?

Approximately 56 million years ago, Earth experienced a rapid global warming event known as the Paleocene-Eocene Thermal Maximum (PETM). Global temperatures rose by $5^\circ\text{C}$ to $8^\circ\text{C}$ in less than 20,000 years. Three scientists present hypotheses regarding the primary source of the greenhouse gases that drove this warming:

Scientist 1
The PETM was primarily caused by the destabilization of marine methane hydrates ($CH_4 \cdot 6H_2O$) on the seafloor. A slight initial warming of deep ocean waters, possibly triggered by changes in ocean circulation, caused these ice-like deposits to melt, releasing massive quantities of methane gas into the water column and atmosphere. Methane is a potent greenhouse gas that rapidly oxidizes to carbon dioxide ($CO_2$). The sudden release of $CH_4$ explains the dramatic, rapid decrease in the carbon-13 to carbon-12 isotope ratio ($^{13}\text{C}/^{12}\text{C}$) observed in the fossil record, as methane is highly enriched in $^{12}\text{C}$.

Scientist 2
The primary driver of the PETM was massive, long-term volcanic eruption associated with the opening of the North Atlantic Ocean (the North Atlantic Igneous Province). These eruptions released vast amounts of carbon dioxide ($CO_2$) and sulfur dioxide ($SO_2$) directly into the atmosphere over thousands of years. The volcanic $CO_2$ caused gradual ocean acidification and global warming. Methane hydrates were not released in significant volumes; the negative $^{13}\text{C}$ isotope excursion was instead caused by the combustion of organic-rich shales and coal beds heated by underground volcanic intrusions (magma), which also released carbon depleted in $^{13}\text{C}$.

Scientist 3
The trigger for the PETM was the impact of a carbon-rich comet. The heat from the impact vaporized the comet's organic matter, injecting a massive amount of $^{12}\text{C}$-rich carbon directly into the upper atmosphere. This impact also triggered widespread forest fires, adding more $CO_2$ to the atmosphere. The impact event explains the suddenness of the carbon isotope excursion and the presence of microtektites (silicate glass spherules formed by impact melting) found in sediment layers dating precisely to the start of the PETM. The ocean warming was a secondary effect of this atmospheric carbon loading, rather than ocean circulation changes.

Three scientists disagree on several aspects of the PETM. Match each scientific issue or concept on the left to the corresponding set of conflicting viewpoints held by Scientist 1, Scientist 2, and Scientist 3 on the right.

During her research in the greenhouse, the botanist compared the rare orchid to the common fern. She noted that [it] grew much faster under artificial blue light. Consequently, she decided to adjust the lighting conditions for the rest of the specimens.

Which choice most clearly and precisely identifies what grew much faster?

In 1915, chemist Alice Ball developed the first successful treatment for leprosy by isolating the active ingredients of chaulmoogra oil. Although her method became the standard of care for decades, but she did not receive immediate recognition for her breakthrough due to her untimely death and a colleague's attempt to claim the work.

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

During the dinner rush, the chef prepared the signature pasta dish more quicker than the sous chef.

Which choice best replaces the underlined phrase to ensure the sentence is grammatically correct?

While exploring the depths of the Mariana Trench, marine biologists discovered several new species of extremophiles. These organisms thrive near hydrothermal vents that spew superheated, mineral-rich water into the ocean. The high pressure and extreme heat would kill most terrestrial life, however, these bacteria have evolved specialized proteins that remain stable under pressure. Which of the following versions of the underlined portion is correct?