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Kristin Fracchia

ACT Science Practice

ACT Science tests are a little like olives; either you love them or you hate them. Yes, skeptical readers, there are some students out there who love the ACT Science test. The nice thing, though, is that no matter where you fall on this love/hate spectrum, you absolutely can learn to at least like the ACT Science test a little more; you just have to get used to it. And this only comes with practice. Specifically, practicing with ACT questions because the ACT Science test is unlike anything you’ve ever seen.

So before we get to the practice questions, here are some of the top strategies that will help you get more cozy with the ACT Science test and be fully prepared for it.

ACT Science Practice Tips


Take Practice ACT Science Tests

The ACT Science test is unique. Unlike the English or Math sections, you can’t do effective preparation for it simply by studying, say, grammar rules or geometry formulas. Heck, you can’t even really prepare for it by studying science. This sounds rather ironic, but it is true. The ACT Science test is far more a test of scientific reasoning and data analysis than a test of science content. So the most effective preparation for the ACT is to do lots of ACT Science questions. We have passages for you to practice with on Magoosh. You can also find five full-length tests in The Real ACT Prep Guide and official practice passages and a full-length test for free on the ACT Student website.

Take Timed Practice Tests

Once you develop a familiarity with the ACT Science test, it is crucial that you practice doing tests under timed conditions. There are generally 6 passages on the Science test and a 35-minute time limit, meaning you have a little less than 6 minutes per passage. Some passages will take you more or less time than others, but time yourself to see if you are able to work at this approximate pace. If you are not, don’t get discouraged; this may just mean you need to focus on doing only 5 of the passages, or even 4, to get your best score. But it’s really important that you figure this out in practice and not on the real thing.

Read Scientific Writing

The more you read about science, the more comfortable you will be with the lingo, terminology, and strange units on the ACT Science test. The Public Library of Science has some good free sources for you to read, but be forewarned that these articles are written for scientists and are more complex than what you will see on the ACT. Therefore, I only recommend this for students who are VERY serious about their science score. If you aren’t ready to get that intense about your ACT Science study, you can devote a little more attention to your school’s science textbooks and lab experiments. Focus particularly on understanding the hypothesis, the control, the variables, and the results of the experiments you encounter.

Review Fundamental Scientific Concepts

Every ACT Science test will have a few questions that require you to bring in outside science knowledge. There won’t be many of these, and any outside knowledge required will be on a pretty basic level. The ACT doesn’t provide a list of what could be tested, but we’ve taken our best guess at what is fair game: study this list of concepts, and you should be in pretty good shape for whatever the ACT throws at you!

You can also check out our free ACT Flashcard App, which contains definitions and examples for all the terms we suggest you know for the ACT Science test.


Ready to try authentic ACT Science passages? Take a stab at the sample passages and questions below.

ACT Science Practice Passages and Questions

Let’s start with a basic ACT Research Summaries passage and easy questions (by ACT Science standards, anyway).

ACT Science Practice: Easy

Two scientists are conducting experiments using a spectrum machine.  The spectrum machine measures the transmittance and absorbance of solutions at various wavelengths of light.

Experiment 1

The scientists insert a curvet into the sample holder and set the dial for 0% transmittance.  They then place solutions of increasing chlorophyll concentration into the spectrum machine and record the transmittance at 4 wavelengths according to the information in Figure 1.


Experiment 2

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The scientists take a prepared solution of chlorophyll and are trying to determine the correct chlorophyll concentration.  According to Beer’s Law, the absorbance (A) of a substance equals the wavelength of the light (b) times the molar absorbance of the material (a) times the concentration (C).  (A=abC)  At a wavelength of 450 nm, a=0.2.

The scientists test three samples of the prepared solution and their results are summarized in Figure 2.


Experiment 3
The scientists are examining 0.2 M solution of red food dye to determine its absorbance. They insert a blank into the spectrum machine, set it to 0 transmittance and then run the sample at three wavelengths.  The results are shown in Figure 3.


ACT Science Practice: Easy Questions

1. If the samples in Activity 3 were run at a wavelength of 400 nm, the transmittance would most likely be closest to:

(A) 70%

(B) 60%

(C) 45%

(D) 30%
2. Which of the following describes the relationship between the wavelength and the transmittance?

(A) As wavelength increases, transmittance increases.
(B) As wavelength increases, transmittance decreases.
(C) As wavelength increases, transmittance stays constant.
(D) There is no relationship between wavelength and transmittance.

ACT Science Practice: Easy Answers and Explanations

1. When observing Figure 3, it can be noted that at 350 nm, the transmittance is 65% and at 450 nm it is 55%. Since 400 nm is halfway between 350 and 450, it is reasonable to assume that the transmittance will be halfway between 65% and 55%. The correct answer is (B).

2. An “indirect” correlation occurs when an increase in one variable decreases the value of another. As the wavelength increases in Figure 3 from 350 nm to 459 nm to 650 nm, the transmittance decreases from 65 to 55 to 35. This suggests a consistent indirect relationship. So the answer is (B).

ACT Science Passage: Medium

This one is a bit harder and is an authentic ACT Science passage from Magoosh ACT. If you want the extra challenge of a little time pressure, we suggest a 3-minute limit to answer the questions, including any reading time.

Malaria is an infectious disease that kills more than 600,000 people every year. Several species of the genus Plasmodium cause malaria, with two of the most common being Plasmodium falciparum and Plasmodium vivax. Though both species cause a very similar illness, P. falciparum malaria is more likely to result in fatalities than P. vivax malaria, while P. vivax malaria is more likely to recur — to return after a period of time during which the patient has been healthy with no parasites present in the blood.

The two species of malaria parasites respond differently to antimalarial medications, but in many areas where malaria is common, testing to determine what type of malaria a patient has is not widely available. Therefore, malaria treatments are often tested against both species of the parasite, and first-line malaria treatments in these regions ideally should be effective against both parasites.

Experiment 1

For many years, public health professionals in Papua New Guinea have recommended a treatment regimen, Drug Combination A, as a first-line malaria treatment. Recently a new treatment regimen, Drug Combination B, has been proposed as a potential replacement for Combination A, and a study was conducted to compare their effectiveness.

Children entering a local health clinic with malaria symptoms were tested to determine which  Plasmodium species they carried and provided an initial treatment. The patients were then randomly assigned Drug Combination A or Drug Combination B, and their blood was tested periodically for the presence of parasites.

Figure 1 shows the results of these treatments.

Figure 1

Figure 1

Figure 1 adapted from Laman M, Moore BR, Benjamin JM, Yadi G, Bona C, et al. “Artemisinin-Naphthoquine versus Artemether-Lumefantrine for Uncomplicated Malaria in Papua New Guinean Children: An Open-Label Randomized Trial,” PLoS Med 11:12 (2014).

Experiment 2

On rare occasions, patients have severe allergic reactions to a compound that is found in both Drug Combination A and Drug Combination B.  In these cases, a second-line treatment must be used. A second study was conducted to determine which of several drug combinations would be the best second-line drug to recommend for use in Papua New Guinea. Table 1 shows the treatment response to the second-line drug combinations.

Table 1

Table 1

ACT Science Practice: Medium

1. According to Figure 1, the percentage of P. falciparum patients with parasites remaining in their blood on Day 14 was approximately:

    1. 1% for patients treated with Drug Combination A, 12% for patients treated with Drug Combination B.
    2. 12% for patients treated with Drug Combination A, 1% for patients treated with Drug Combination B.
    3. 7% for patients treated with Drug Combination A, 14% for patients treated with Drug Combination B.
    4. 0% for both drug combinations.

2. Recurrences of P. vivax malaria are known to be caused by hypnozoites, a form of the malaria parasite that can go dormant in the patient’s liver for up to two weeks, that remain alive following the initial treatment. Based on the data in Figure 1, which of the following conclusions is most likely to be true?

    1. Drug Combination A eliminates hypnozoites in all patients, but Drug Combination B eliminates hypnozoites only in some patients.
    2. Drug Combination B eliminates all hypnozoites, but Drug Combination A eliminates hypnozoites only in some patients.
    3. Drug Combination B eliminates all hypnozoites in all patients, but Drug Combination A does not eliminate any hypnozoites.
    4. Neither treatment kills hypnozoites.

3. Suppose a patient is brought to the clinic with a life-threatening case of P. falciparum malaria. As the patient’s condition is deteriorating quickly, it is essential that they be given the treatment that eliminates parasites from their blood within 7 days. Based on the data from Experiments 1 and 2, which treatment should they be given?

    1. Drug Combination A
    2. Drug Combination D
    3. Drug Combination E
    4. Drug Combination B


ACT Science Practice: Medium Answers and Explanations

Ready to check your answers? Here we go.

Whether you got all of the questions right (congrats!), or you missed one (or a few), be sure to read the following explanations.

ACT Study Tip: Even if you get the right answer on practice problems, check the explanation to make sure that your logic holds. Sometimes we get the right answer by accident … but don’t expect to get this lucky on test day! Make sure that you know why you get answers right and wrong.

1. a – 1% for patients treated with Drug Combination A, 12% for patients treated with Drug Combination B.

To find this answer, look at Figure 1 and make sure you are looking at the P. falciparum graph. We want to know the percentage of patients with parasites in their blood on Day 14, so we need to find Day 14 on the horizontal axis and check the vertical axis value (the percentage of patients with parasites) of each line at Day 14. For Drug Combination A (the solid line) the line is at 1% and for Drug Combination B (the dotted line) it is at 12%, so our answer is (A).

2. bDrug Combination B eliminates all hypnozoites, while Drug Combination A eliminates hypnozoites only in some patients.

In Experiment 1, all P. vivax patients on Drug Combination B were successfully treated and remained free of parasites through the end of the study, but some patients who were treated with Drug Combination A experienced a recurrence, as we can tell from the data for Days 28 and 42 of the study. If recurrences are caused by surviving hypnozoites, this means that Drug Combination A leaves behind living hypnozoites in some patients. Our answer is (B).

3. c – Drug Combination E

This question requires us to compare data between the two different experiments and two different figures. We need to examine the percentage of patients that remained infected with P. falciparum parasites on Day 7 for each of the four different drug combinations listed in the answer choices. On Day 7, approximately 12% of the patients treated with Drug Combination A remained infected and 30% of patients treated with Drug Combination B remained infected. The chart in Experiment 2 tells us how many patients were free of parasites, not infected, so be careful to note this difference. 51% of P. falciparum patients treated with Drug Combination D were free of parasites, but 100% of P. falciparum patients treated with Drug Combination E were free of parasites, making (C) our answer.

How did you do? Even if you felt challenged by these questions, it’s important to become familiar with the types of problems that you will be asked in the ACT Science section. Using good strategies and completing more ACT science practice questions will help you become more comfortable with the section and more likely to work your way to a good ACT score!


About Kristin Fracchia

Dr. Kristin Fracchia makes sure Magoosh's sites are full of awesome, free resources that can be found by students prepping for standardized tests. With a PhD from UC Irvine and degrees in Education and English, she’s been working in education since 2004 and has helped students prepare for standardized tests, as well as college and graduate school admissions, since 2007. She enjoys the agony and bliss of trail running, backpacking, hot yoga, and esoteric knowledge.

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