ACT Science 2 — Questions and Answers
Question 1: On an ACT Science data representation passage, a graph shows reaction rate increasing then leveling off as temperature rises. What does the leveling-off most likely indicate?
- The enzyme or catalyst has denatured or reached saturation (Correct answer)
- Temperature stopped increasing
- The reaction reversed direction
- Measurement error occurred
Correct answer: The enzyme or catalyst has denatured or reached saturation
A plateau in rate despite rising temperature usually signals denaturation or saturation of the catalyst.
Question 2: Two scientists disagree about whether a planet's water came from comets or volcanic outgassing. This passage type on the ACT is called:
- Conflicting Viewpoints (Correct answer)
- Data Representation
- Research Summaries
- Experimental Design
Correct answer: Conflicting Viewpoints
Passages presenting opposing hypotheses are Conflicting Viewpoints passages.
Question 3: A table lists density values for four liquids. Which liquid will float on top if poured into one container?
- The one with the lowest density (Correct answer)
- The one with the highest density
- The one with the most volume
- The one tested last
Correct answer: The one with the lowest density
Less dense liquids float above denser ones.
Question 4: In a Research Summaries passage, Experiment 2 differs from Experiment 1 only by adding a control group with no treatment. The purpose of this control is to:
- Provide a baseline for comparison (Correct answer)
- Increase the treatment dose
- Speed up the reaction
- Reduce the sample size
Correct answer: Provide a baseline for comparison
A control group establishes a baseline against which treated groups are compared.
Question 5: A line graph shows two variables that rise together in a straight diagonal line. This relationship is best described as:
- Directly proportional (Correct answer)
- Inversely proportional
- Exponential
- No correlation
Correct answer: Directly proportional
A straight upward line through the origin indicates direct proportionality.
Question 6: An experiment measures plant growth at pH 4, 6, 7, and 9, with tallest growth at pH 7. What is the independent variable?
- pH of the solution (Correct answer)
- Plant height
- Amount of sunlight
- Number of leaves
Correct answer: pH of the solution
The independent variable is what the experimenter deliberately changes—here, pH.
Question 7: A passage states a result occurred 'at standard temperature and pressure (STP).' STP is most useful in ACT Science questions because it:
- Sets a fixed reference condition for comparing gas measurements (Correct answer)
- Guarantees a chemical reaction occurs
- Eliminates the need for a control group
- Doubles the reaction rate
Correct answer: Sets a fixed reference condition for comparing gas measurements
STP provides a standardized reference so gas data can be fairly compared.
ACT Science 2
On an ACT Science data representation passage, a graph shows reaction rate increasing then leveling off as temperature rises.
What does the leveling-off most likely indicate?