All practice questions

### The Red Color of Jupiter's Great Red Spot

The Great Red Spot (GRS) is a massive storm in Jupiter's atmosphere. While the storm itself has persisted for centuries, the exact chemical processes responsible for its distinct reddish color remain a topic of debate. Two scientists propose different hypotheses.

Scientist 1
The GRS's red color is produced in the upper atmosphere through the photolysis of ammonium hydrosulfide ($NH_4SH$) gas by solar ultraviolet (UV) radiation. $NH_4SH$ is carried upward from lower cloud decks by convection. When exposed to solar UV light at the top of the GRS, $NH_4SH$ decomposes into ammonium polysulfides and sulfur allotropes (such as $S_8$). These sulfur-based compounds highly absorb ultraviolet and blue light while reflecting red light, giving the cloud tops their red appearance. This reaction occurs exclusively in the uppermost atmospheric layers where UV light is strong enough to break chemical bonds.

Scientist 2
The red color is generated by the radiolysis of phosphine ($PH_3$) and ammonia ($NH_3$) gases, driven by high-energy cosmic rays and magnetospheric electrons. Because these charged particles possess high energy, they penetrate deep into the middle and lower layers of the GRS clouds, initiating chemical reactions that UV light cannot. The radiolysis of $PH_3$ and $NH_3$ produces red phosphorus polymers ($P_4$). Strong upward convective currents within the GRS then transport these red polymers to the visible cloud tops.

According to the passage, which of the following statements best describes the core hypothesis of Scientist 2 regarding the chemical origin of the Great Red Spot's red color?

Read the passage below. Fill in the blank with the correct form of the verb in parentheses to maintain a consistent grammatical construction and avoid an inappropriate shift in verb tense.

The sentence below contains a blank. Which form of the verb 'to reveal' correctly completes the sentence while maintaining proper subject-verb agreement in the present tense? Write the correct verb form in the blank.

The city council voted to censor the representative for her ethical violations, drawing attention to the strict standards expected of public officials.

Which of the following is the correct choice for the underlined portion of the sentence?

A portion of the passage below is underlined.

In 1903, during a frosty streetcar ride in New York City, Mary Anderson observed the driver repeatedly opening the front window to clear away falling sleet. Inspired by this struggle, she designed a hand-operated wooden blade that could sweep moisture from the glass, [which was a task that was performed by a driver from inside the vehicle].

Which choice best eliminates wordiness while maintaining grammatical correctness?

A group of students conducted a series of trials to study the interference patterns of light using a double-slit setup. They measured the fringe spacing, $w$ (the distance between adjacent bright bands on a screen). The relationship between the fringe spacing and the experimental parameters is given by:

where $\lambda$ is the wavelength of the light source, $L$ is the distance from the slits to the screen, and $d$ is the distance between the two slits.

Match each change in the experimental setup to its corresponding effect on the fringe spacing ($w$).

Located deep inside a sandstone mountain on a remote Arctic island, the Svalbard Global Seed Vault's primary mission is to preserve millions of crop samples. This facility serves as a global safety net against the loss of biodiversity during large-scale crises. By housing duplicates of seeds from around the world, scientists hope to safeguard the future of the global food supply.

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

### Models of the Origin of Eukaryotic Organelles

Eukaryotic cells are distinguished from prokaryotic cells by the presence of a membrane-bound nucleus and specialized organelles, such as mitochondria and chloroplasts. Scientists have proposed different models to explain the origin of these complex organelles.

Model 1 (Autogenous Model)
This model proposes that eukaryotic organelles evolved gradually through the invagination (folding inward) and subsequent specialization of the ancestral prokaryotic cell's own plasma membrane. According to this model, a portion of the outer membrane pinched off inside the cell to surround the genetic material, forming the nucleus and the endoplasmic reticulum. Over time, other invaginations of the cell membrane compartmentalized specific metabolic pathways, eventually evolving into mitochondria and chloroplasts. Thus, all internal membrane-bound structures share a common lineage and evolved within a single ancestral prokaryotic population without genetic contribution from external organisms.

Model 2 (Endosymbiotic Model)
This model proposes that key eukaryotic organelles arose when a large, anaerobic prokaryotic host cell engulfed smaller, free-living aerobic or photosynthetic prokaryotes. Instead of digesting the engulfed cells, the host cell entered a symbiotic relationship with them. Specifically, an engulfed aerobic bacterium (resembling modern alpha-proteobacteria) became the mitochondrion, providing the host with efficient ATP production. Later, an engulfed photosynthetic bacterium (resembling modern cyanobacteria) became the chloroplast. Consequently, mitochondria and chloroplasts evolved from distinct, independent evolutionary lineages separate from the host cell, explaining why they possess their own circular DNA, double membranes, and independent reproductive mechanisms.

Match each biological feature or claim on the left with the correct comparative description of how it is addressed by Model 1 and Model 2 on the right.

Many literary historians argue that the detailed records kept by the early Sumerian scribes were more comprehensive then other civilizations of the same era.

Which choice best completes the sentence by maintaining logical comparison and correct grammatical usage?

Ancient Roman concrete is renowned for its durability, allowing structures like the Pantheon to remain standing for nearly two thousand years. Unlike modern concrete, which begins to degrade within decades, the Roman mixture contains volcanic ash, this unique ingredient undergoes a chemical reaction with seawater that crystallizes and strengthens the material over time. Because of this self-healing process, the concrete actually grows stronger when exposed to the elements.

Which of the following choices represents the best revision of the underlined portion?

During the Paleocene-Eocene Thermal Maximum (PETM), global temperatures rose rapidly, and marine sediment records show a sharp decrease in the ratio of carbon-13 to carbon-12 (represented as $\delta^{13}\text{C}$, measured in parts per thousand, $‰$). Two scientists discuss the source of this carbon isotope excursion.

Scientist 1
The PETM warming was triggered by the sudden dissociation of marine methane hydrates (solid lattices of ice trapping methane gas) on the seafloor. Methane hydrates contain biogenic methane, which is highly depleted in $^{13}\text{C}$ (having a $\delta^{13}\text{C}$ value of approximately $-60\text{‰}$). Due to this extremely negative signature, releasing approximately $2{}000\text{ Gt}$ (gigatons) of carbon from hydrates is sufficient to cause the observed global decrease in marine $\delta^{13}\text{C}$.

Scientist 2
The carbon release was caused by volcanic intrusions (sills) from the North Atlantic Igneous Province heating organic-rich sedimentary basins. This heated organic matter released thermogenic methane and carbon dioxide gas. Thermogenic carbon is moderately depleted in $^{13}\text{C}$, with an average $\delta^{13}\text{C}$ value of approximately $-35\text{‰}$. To produce the observed global decrease in marine $\delta^{13}\text{C}$ using this less-depleted carbon source, a much larger release of carbon—approximately $4{}500\text{ Gt}$—was required.

Suppose a new geochemical reconstruction determines that the total mass of carbon released during the PETM was approximately $2{}100\text{ Gt}$. How does this finding align with the viewpoints of the two scientists?

The following sentences are from a paragraph about restoring historical sound recordings. Arrange the sentences in the most logical order to create a cohesive paragraph that begins with the most effective introduction and ends with the most effective conclusion.

After marinating in a mixture of soy sauce and ginger for several hours, the chef grilled the salmon fillet to perfection.

Which of the following versions of the underlined portion represents the most grammatically correct and logical sentence?

Having spent decades documenting the volatile fluctuations of geothermal geysers in Iceland, the volcanologist was completely inured from the sudden, deafening blasts that frequently startled tourists.

Which choice best replaces the underlined portion of the sentence?

In 1948, graduate student Bernard Silver overheard a supermarket executive asking a university dean to develop a system that could automatically capture product information at checkout. Silver mentioned this challenge to his friend Norman Joseph Woodland, who became obsessed with finding a solution. Woodland initially tried using ultraviolet ink, but the ink faded too quickly and was expensive. Indeed, he focused his efforts on creating a physical pattern of lines inspired by Morse code.

Which choice provides the most logical transition from the preceding sentence?

In 1903, Mary Anderson was granted a patent for her window-cleaning device. Initially, local streetcar companies rejected the invention, this innovative and novel design eventually became standard equipment on all motor vehicles.

Which choice most effectively and grammatically completes the sentence while eliminating redundancy?

The following sentence contains a modifier error in the underlined portion: 'By analyzing the chemical composition of the core sample, the age of the glacier was determined by the scientists.' To correct this error, what phrase should replace the underlined portion to ensure the sentence is grammatically correct?

Launched in 1977 to study the outer solar system, the Voyager 1 spacecraft provided humanity with its first close-up images of Jupiter and Saturn. As it traveled past these gas giants, the probe revealed active volcanoes on Jupiter's moon Io and complex structures within Saturn's rings. Decades later, Voyager 1 crossed the heliopause into interstellar space, where it [continues] to transmit valuable data back to Earth.

Which choice best maintains the established verb tense of the passage?

Iceland utilizes geothermal energy to heat its homes and generate electricity. Because this energy is harnessed directly from underground volcanic systems, it currently provides a reliable source of power at the present time to the majority of the country's residents.

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

While reviewing the final draft of the literary anthology, the head publisher suggested that the guest editor and me should coordinate they're efforts to meet the upcoming submission deadline.

Which of the following options represents the grammatically correct choice to replace the underlined portion of the sentence?