ACT (Enhanced) practice questions
216 free questions with answers and explanations.
- 1.A scientist develops a computational model to simulate the spread of a new viral infection in a population. The model incorporates parameters such as transmission rate, recovery rate, and population density. To assess the model's ability to predict future outbreaks, the scientist applies it to historical data from a similar past epidemic and compares the model's output to the actual observed spread. What is the scientist primarily doing in this scenario?Science
- 2.A novelist describes a character's room in meticulous detail: 'The walls were adorned with yellowing maps of forgotten lands, their edges curled and brittle. A tall, narrow bookshelf groaned under the weight of ancient tomes, many with pages dog-eared and spines cracked. On the desk, a single flickering candle illuminated a half-finished letter, its ink faded, next to a tarnished brass compass pointing resolutely north.' What mood does this setting primarily evoke?Reading
- 3.A student is revising an argumentative essay and wants to introduce evidence from a source to support a claim. They have written the following sentence: "The recent economic downturn has disproportionately affected low-income families; therefore, governmental intervention is crucial." The student wants to add a statistic from a report that states, "Unemployment rates for households earning below the median income increased by 15% in the last quarter." Where should this statistic be most effectively integrated to strengthen the argument?English
- 4.A student is writing an argumentative essay and wants to introduce a counterargument before refuting it. They have written the following sentences: 'Many believe that social media platforms are primarily detrimental to mental health. This perspective overlooks the significant benefits of online communities and support networks.' Which transitional phrase best connects these two sentences to effectively introduce and then counter the initial point?English
- 5.A research team is studying the migratory patterns of a bird species. They tag 100 birds with GPS trackers and release them. Over the next year, they collect data on the birds' locations. They notice that 80% of the tagged birds follow a similar route, while 20% deviate significantly. Based on this observation, the team proposes a model that suggests a primary migratory route influenced by prevailing winds, but also acknowledges individual variations. What is a key strength of this model?Science
- 6.A pharmaceutical company is testing a new drug designed to lower blood pressure. They conduct a clinical trial with 200 participants, randomly divided into two groups. Group A receives the new drug, and Group B receives a placebo. Neither the participants nor the administering staff know who is receiving the drug or the placebo. After 8 weeks, the average blood pressure reduction in Group A is 15 mmHg, while in Group B it is 3 mmHg. What is the most significant advantage of using a 'double-blind' protocol in this experiment?Science
- 7.A biologist is studying the effect of a new pesticide on a specific insect population. They set up three experimental plots: Plot A receives the full dose of the pesticide, Plot B receives a half dose, and Plot C receives no pesticide. All other environmental conditions (temperature, humidity, light) are kept identical across the plots. After one month, the insect population density in each plot is measured. What is the role of Plot C in this experiment?Science
- 8.A student is designing an experiment to investigate how the concentration of a salt solution affects the boiling point of water. They plan to prepare solutions with 0%, 5%, 10%, and 15% salt by mass. To ensure the reliability of their results, what is the most appropriate action the student should take?Science
- 9.A student is writing an informative paragraph about the history of the internet. They have written the following sentence: "The internet, which was originally developed by the U.S. military, has since become a global communication network." The student wants to combine this information with another sentence: "It allows billions of users worldwide to share information and connect." Which of the following combines these sentences most effectively and grammatically?English
- 10.In a philosophical essay, the author introduces a complex ethical dilemma, then presents two opposing viewpoints with equal rigor, exploring the strengths and weaknesses of each without explicitly favoring one. The essay concludes by suggesting that the reader must weigh the evidence and make their own informed decision. What is the author's primary rhetorical strategy in this essay?Reading
- 11.Read the following excerpt from a science textbook: "Photosynthesis, the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll, is fundamental to most life on Earth. It converts light energy into chemical energy, which is then stored in organic compounds like glucose. This complex biochemical pathway involves two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). During the light-dependent reactions, water is split, releasing oxygen, and energy-carrying molecules (ATP and NADPH) are produced. These molecules then power the light-independent reactions, where carbon dioxide is fixed into sugars." Which of the following best describes the primary function of chlorophyll in photosynthesis?Reading
- 12.A historical text describes the rise of ancient Rome: "Rome's strategic location on the Tiber River, offering both fertile land and access to trade routes, provided the initial impetus for its growth. This geographical advantage, coupled with a robust military structure and adaptable political institutions, allowed the nascent Republic to consolidate power across the Italian peninsula and eventually dominate the Mediterranean world." The text primarily uses which organizational pattern to explain Rome's ascendancy?Reading
- 13.An environmental report concludes with a section titled 'The Imperative for Sustainable Practices.' This section outlines the long-term consequences of current resource depletion and pollution, then details various strategies for conservation, renewable energy adoption, and waste reduction. What is the primary purpose of this concluding section?Reading
- 14.A student is reviewing a peer's argumentative essay and notices a sentence that contains a dangling modifier. The sentence reads: "Walking through the park, the colorful leaves crunched underfoot." Which revision correctly fixes the dangling modifier?English
- 15.A literary critic is reviewing a novel that features a protagonist who constantly questions societal norms, challenges authority, and often finds himself in conflict with established institutions. The critic notes that this character's actions, while sometimes leading to personal hardship, consistently drive the plot forward and force other characters to re-evaluate their own beliefs. Which literary archetype does this protagonist most closely embody?Reading
- 16.A student is writing an argumentative essay and wants to ensure that their claims are supported by credible evidence. They have found a statistic from a government website and are considering including a personal anecdote from a friend. Which of the following best describes the appropriate use of these two types of evidence in an academic essay?English
- 17.A biologist is studying the growth rate of a specific bacterial strain under varying nutrient concentrations. They conduct experiments at 0.1%, 0.5%, 1.0%, and 2.0% nutrient concentrations, measuring bacterial population density after 24 hours. The initial population density was 10^3 cells/mL for all experiments. The results are: 0.1% -> 1.5 x 10^4 cells/mL; 0.5% -> 8.0 x 10^4 cells/mL; 1.0% -> 1.2 x 10^5 cells/mL; 2.0% -> 1.3 x 10^5 cells/mL. Based on these results, which inference can be made about the bacterial growth?Science
- 18.A student is writing an essay and wants to smoothly transition between two paragraphs. The first paragraph discusses the challenges of space exploration, and the second paragraph will discuss technological advancements that are overcoming these challenges. Which of the following transition words or phrases would be most effective at the beginning of the second paragraph?English
- 19.A student measures the time it takes for a ball to roll down ramps of varying angles. They record the following times (in seconds) for ramp angles of 10°, 20°, 30°, and 40°: 3.5, 2.8, 2.2, 1.7. What is the most appropriate conclusion regarding the relationship between ramp angle and rolling time?Science
- 20.A scientific report discusses the impact of climate change on ocean ecosystems: "Rising sea temperatures are leading to coral bleaching events of unprecedented scale and frequency. This phenomenon, where corals expel symbiotic algae, not only threatens the biodiversity of coral reefs but also impacts the livelihoods of coastal communities reliant on these ecosystems for fishing and tourism. The long-term implications include significant reductions in marine species and increased coastal vulnerability to storms." The phrase "unprecedented scale and frequency" primarily serves to:Reading
- 21.A student is revising their essay and wants to ensure consistent verb tense. They have written the following paragraph: 'Sarah walked into the room. She sees her friend sitting by the window. They began to chat excitedly.' Which of the following revisions corrects the verb tense inconsistency?English
- 22.A research assistant is analyzing data from an experiment on bacterial growth under varying pH levels. They have collected the following average colony counts after 24 hours: - pH 6.0: 120 colonies - pH 6.5: 180 colonies - pH 7.0: 250 colonies - pH 7.5: 230 colonies - pH 8.0: 160 colonies Based on these results, what is the most reasonable inference about the optimal pH for this bacterial strain's growth?Science
- 23.A student is writing an essay about the history of jazz music and wants to ensure their sentences are varied and engaging. They have just written a sentence detailing the origins of ragtime. Which of the following sentence structures would best introduce the subsequent evolution into swing music, creating a smooth and compelling transition?English
- 24.A student is investigating the effect of different types of soil on the growth of bean plants. They prepare three pots: Pot A with sandy soil, Pot B with clay soil, and Pot C with loam soil. All pots receive the same amount of water, sunlight, and seeds from the same batch. After three weeks, they measure the height of the plants. To improve the reliability of their results, what is the most important modification the student should make to their experimental design?Science
- 25.A historian is analyzing two primary sources about the American Civil War. Source A is a letter written by a Union soldier to his family, describing camp life and battles. Source B is an official dispatch from a Confederate general detailing troop movements and strategic objectives. Which of the following statements most accurately compares the likely perspective and focus of these two sources?Reading
- 26.A student is writing an argumentative essay and wants to introduce a counterargument before refuting it. They have written the following sentence: 'Some critics argue that renewable energy sources are unreliable. However, this perspective overlooks recent advancements in battery storage technology.' Which of the following transitional phrases, if replacing 'However,' would best emphasize the direct contradiction of the counterargument?English
- 27.A student investigates the effect of temperature on the rate of enzyme activity. They set up three identical experiments, each containing the same enzyme and substrate concentration. Experiment 1 is conducted at 20°C, Experiment 2 at 37°C, and Experiment 3 at 50°C. The amount of product formed is measured after 10 minutes in each experiment. Which of the following is the independent variable in this investigation?Science
- 28.A student is drafting an essay and wants to ensure that all verbs agree with their subjects. They have written the following sentence: The team of researchers, along with its lead scientist, *is/are* presenting their findings at the conference next month. Which verb form correctly completes the sentence?English
- 29.A travel blog post describes a remote mountain village: "Nestled deep within the mist-shrouded peaks, the village of Eldoria seemed untouched by time. Ancient stone cottages clung precariously to the mountainside, their slate roofs glistening with perpetual damp. A faint, earthy scent of woodsmoke and damp moss hung in the air, while the distant murmur of a hidden waterfall provided the village's only soundtrack. Life here moved at a glacial pace, dictated by the rhythm of the seasons and the whisper of the wind." The author's description of Eldoria primarily functions to establish:Reading
- 30.A student is investigating the relationship between the mass of a pendulum bob and its period (time for one complete swing). They conduct an experiment using three different masses (10g, 20g, 30g) while keeping the length of the pendulum string and the release angle constant. For each mass, they measure the time for 20 oscillations and then calculate the average period. Which of the following is a potential source of experimental error that could affect the accuracy of the results?Science
- 31.A student is drafting an email to their professor to request an extension on a research paper. They want to maintain a formal and respectful tone. Which of the following opening sentences is most appropriate?English
- 32.A philosopher writes: 'The concept of free will, often championed as the cornerstone of human dignity, is in fact an elaborate illusion. Every choice we make, every thought we entertain, is merely the inevitable outcome of prior physical causes and genetic predispositions, operating within a deterministic universe. To believe otherwise is to ignore the fundamental laws of nature.' Which of the following statements would most directly strengthen the philosopher's argument?Reading
- 33.A student is writing a narrative essay and wants to create a vivid and immersive setting. They are describing a dense forest at dusk. Which of the following sentences most effectively uses sensory details to achieve this effect? Which sentence best uses sensory details?English
- 34.A chemist is performing a titration to determine the concentration of an unknown acid. They record the initial volume of the titrant (0.50 mL), the final volume of the titrant (23.75 mL), and the concentration of the titrant (0.100 M). If the chemist calculates the volume of titrant used as 23.25 mL, but the actual volume delivered by the burette was 23.35 mL due to a slight parallax error during reading, how would this error affect the calculated concentration of the unknown acid?Science
- 35.A historical text describes the Roman Empire's expansion, detailing its military campaigns, political strategies for conquered territories, and the assimilation of diverse cultures into Roman society. The text then transitions to discussing the eventual decline, citing economic instability, internal strife, and external invasions. What is the primary organizational pattern used in this passage?Reading
- 36.A geophysicist is studying seismic wave data to understand Earth's interior structure. They observe that P-waves (primary waves) can travel through both solids and liquids, but their speed changes significantly at certain depths. S-waves (secondary waves), however, are observed to travel only through solids and are completely absent in the outer core. What can be inferred about the state of matter of Earth's outer core based on this seismic data?Science
- 37.A student is writing an essay about the impact of technology on communication. They want to introduce a paragraph discussing the benefits of instant messaging. Which of the following transitional phrases would best introduce this topic?English
- 38.A group of students is designing an experiment to investigate how the concentration of a sugar solution affects the rate of fermentation by yeast. They plan to prepare four different sugar solutions (5%, 10%, 15%, and 20% sugar by mass). For each solution, they will add a fixed amount of yeast and incubate the mixtures at a constant temperature. They decide to measure the volume of carbon dioxide gas produced over 30 minutes as an indicator of the fermentation rate. Which of the following would be the most effective way to ensure the reliability of their results?Science
- 39.A historian is analyzing a historical document from the 18th century. The document is a personal letter written by a merchant to his family, detailing his business ventures and daily life. The historian notes that the merchant frequently uses phrases like 'by God's grace,' 'divine providence,' and 'if the Lord wills it' when discussing his plans and successes. What can the historian most reasonably infer about the merchant's worldview based on these linguistic choices?Reading
- 40.A student is investigating the effect of different pH levels on the growth of a specific type of mold. They prepare five petri dishes, each containing the same amount of nutrient agar. Dish 1 has a pH of 4, Dish 2 a pH of 5, Dish 3 a pH of 6, Dish 4 a pH of 7, and Dish 5 a pH of 8. All dishes are inoculated with the same amount of mold spores and incubated at 25°C for 7 days. Which of the following would be the most appropriate dependent variable to measure in this experiment?Science
- 41.A scientist develops a computational model to simulate the spread of a new viral infection in a population. The model incorporates factors such as transmission rate, recovery rate, and population density. After running the simulation, the model predicts a peak in infections occurring 30 days after the initial outbreak, followed by a gradual decline. Which of the following would be the most effective way to validate this model?Science
- 42.A student is writing an argumentative essay and wants to introduce a counterargument that acknowledges an opposing viewpoint before refuting it. They have written the following sentence: "Some critics argue that renewable energy sources are unreliable; however, recent technological advancements have largely mitigated these concerns." Which of the following transitional words or phrases could best replace "however" to more strongly emphasize the shift from acknowledging the counterargument to presenting the rebuttal?English
- 43.A critic reviews a film, stating: 'The director's relentless pursuit of visual grandeur, while undeniably breathtaking, ultimately overshadows any meaningful character development. We are left with stunning panoramas and intricate set pieces, but characters whose struggles feel hollow and unearned. It's a feast for the eyes, a famine for the soul.' Which of the following best summarizes the critic's overall assessment of the film?Reading
- 44.A research team is investigating the genetic diversity of a population of endangered butterflies. They decide to collect butterflies from a single large, easily accessible meadow, assuming it represents the entire population. However, the endangered species is known to inhabit several geographically distinct areas with varying vegetation types. What type of methodological flaw is most likely to affect their results?Science
- 45.A literary critic writes: 'The author's prose, while undeniably elegant and meticulously crafted, often sacrifices narrative momentum for lengthy philosophical digressions, leaving the reader with a sense of intellectual satiety but narrative stagnation.' What is the critic's main assessment of the author's writing style?Reading
- 46.A researcher conducts an experiment to test the effectiveness of a new fertilizer on plant growth. They divide 60 identical plants into three groups: Group A (control, no fertilizer), Group B (low concentration fertilizer), and Group C (high concentration fertilizer). All other conditions (light, water, soil type) are kept constant. After four weeks, the average height of plants in each group is measured. Which of the following would constitute a valid control group for this experiment?Science
- 47.A seismologist is studying the internal structure of a newly discovered planet. They detect two types of seismic waves, P-waves and S-waves, traveling through the planet's interior. They observe that S-waves completely disappear at a certain depth, while P-waves continue to propagate but with a change in speed and direction. What is the most likely inference about the planet's interior at that specific depth?Science
- 48.A student is writing an informative essay about sustainable agriculture. They want to avoid making a logical fallacy in their argument. They have written the following statement: 'Since many successful farmers are now adopting organic practices, it is clear that organic farming is the superior method for all agricultural needs.' Which of the following logical fallacies does this statement most clearly demonstrate?English
- 49.A geophysicist is studying seismic wave data to understand Earth's interior structure. They detect two distinct types of waves: P-waves that travel through both solids and liquids, and S-waves that only travel through solids. By analyzing the arrival times and paths of these waves at different seismic stations, the geophysicist infers the presence of a liquid outer core and a solid inner core. This inference is primarily based on which characteristic of seismic waves?Science
- 50.A chemist performs an experiment to determine the concentration of an unknown acid. They titrate the acid with a known concentration of base, using an indicator to detect the equivalence point. They repeat the titration three times and obtain the following volumes of base required: 25.15 mL, 25.20 mL, and 25.18 mL. Which of the following best describes the precision of these measurements?Science