ACT Practice Test: Science Questions
Directions: This section contains several passages. After each passage, answer the questions that follow. Each question has four answer choices (A, B, C, D). Choose the best answer based on the information provided in the passage, graphs, or tables. You may refer back to the passage as needed.
Passage I: Temperature and Enzyme Activity (Data Representation)
A biology class studied how temperature affects enzyme activity. The rate of reaction was measured at different temperatures.
| Temperature (°C) | Reaction Rate (units/min) |
|---|---|
| 10 | 12 |
| 20 | 25 |
| 30 | 40 |
| 40 | 55 |
| 50 | 48 |
| 60 | 20 |
Questions 1–7
1. At which temperature is the reaction rate highest?
A. 10°C
B. 30°C
C. 40°C
D. 60°C
2. Between which temperatures does the enzyme activity begin to decline?
A. 10–20°C
B. 20–30°C
C. 40–50°C
D. 50–60°C
3. What is the general relationship between temperature and reaction rate from 10°C to 40°C?
A. Decreasing
B. Constant
C. Increasing
D. Random
4. What is the reaction rate difference between 30°C and 50°C?
A. 8
B. 10
C. 12
D. 15
5. At 60°C, the enzyme is most likely:
A. Highly active
B. Denatured
C. Unchanged
D. Replicated
6. Which temperature shows a rate closest to half of the maximum rate?
A. 20°C
B. 30°C
C. 50°C
D. 60°C
7. What conclusion is best supported?
A. Enzyme activity increases indefinitely
B. Enzymes stop working at all temperatures
C. Enzyme activity increases then decreases after an optimum temperature
D. Temperature has no effect on enzymes
Passage II: Plant Growth Experiment (Research Summary)
Two groups of plants were grown under different light conditions.
- Group A: Natural sunlight
- Group B: Artificial LED light
After 14 days, average heights were recorded.
- Group A: 18 cm
- Group B: 15 cm
Questions 8–14
8. What was the independent variable?
A. Plant height
B. Light type
C. Time
D. Temperature
9. What was the dependent variable?
A. Light type
B. Plant height
C. Soil type
D. Water amount
10. Which group grew taller?
A. Group A
B. Group B
C. Both equal
D. Neither
11. The purpose of this experiment is to study:
A. Photosynthesis rate differences
B. Effect of light on plant growth
C. Soil nutrient levels
D. Water absorption
12. If Group B grew 20 cm instead, what would this suggest?
A. LED light is better for growth
B. Sunlight is harmful
C. Light has no effect
D. Plants stop growing under sunlight
13. What is a controlled variable likely kept constant?
A. Light type
B. Plant species
C. Plant height
D. Growth rate
14. What conclusion is best supported?
A. Artificial light always stops growth
B. Natural sunlight supports slightly better growth in this case
C. Plants do not need light
D. LED light kills plants
Passage III: Motion of a Car (Graph Interpretation)
A car’s speed was recorded over time:
- 0 sec → 0 m/s
- 2 sec → 4 m/s
- 4 sec → 8 m/s
- 6 sec → 8 m/s
- 8 sec → 6 m/s
Questions 15–21
15. When is acceleration highest?
A. 0–2 sec
B. 2–4 sec
C. 4–6 sec
D. 6–8 sec
16. At what time does the car maintain constant speed?
A. 0–2 sec
B. 2–4 sec
C. 4–6 sec
D. 6–8 sec
17. What is the maximum speed?
A. 4 m/s
B. 6 m/s
C. 8 m/s
D. 10 m/s
18. The car begins to slow down at:
A. 2 sec
B. 4 sec
C. 6 sec
D. 8 sec
19. What is the change in speed from 4 sec to 8 sec?
A. 0
B. 2
C. 4
D. 8
20. What type of motion occurs from 4–6 sec?
A. Acceleration
B. Constant velocity
C. Deceleration
D. Rest
21. Overall, the motion shows:
A. Only acceleration
B. Acceleration then constant then deceleration
C. Constant motion only
D. Random motion
Passage IV: Chemical Reaction Rates (Research Summary)
A chemist tested how concentration affects reaction time.
| Concentration (M) | Time (sec) |
|---|---|
| 0.1 | 50 |
| 0.2 | 30 |
| 0.3 | 20 |
| 0.4 | 15 |
Questions 22–27
22. As concentration increases, reaction time:
A. Increases
B. Decreases
C. Stays same
D. Random
23. Fastest reaction occurs at:
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
24. Which is true?
A. Higher concentration slows reaction
B. Lower concentration speeds reaction
C. Higher concentration speeds reaction
D. Concentration has no effect
25. Difference in time between 0.1 M and 0.4 M is:
A. 25 sec
B. 30 sec
C. 35 sec
D. 40 sec
26. Reaction rate is highest when time is:
A. Highest
B. Lowest
C. Average
D. Zero
27. What is best conclusion?
A. Concentration increases reaction speed
B. Concentration decreases reaction speed
C. No relationship exists
D. Time is unrelated to reaction rate
Passage V: Earth Science – Rock Layers
A geologist studied rock layers:
- Layer A (top): Sandstone
- Layer B: Limestone
- Layer C: Shale
- Layer D (bottom): Igneous rock
Questions 28–33
28. Which layer is oldest?
A. A
B. B
C. C
D. D
29. Which layer is youngest?
A. A
B. B
C. C
D. D
30. Principle used here is:
A. Gravity
B. Superposition
C. Diffusion
D. Photosynthesis
31. Fossils are most likely found in:
A. Igneous rock
B. Shale
C. Lava
D. Mantle
32. Limestone is between:
A. A and C
B. B and D
C. C and D
D. A and B
33. If a fossil is found in Layer C, it is:
A. Younger than A
B. Older than D
C. Older than B
D. All of the above
Passage VI: Conflicting Viewpoints (Energy Sources)
Scientist 1: Solar energy is best because it is renewable and clean.
Scientist 2: Wind energy is better because it produces electricity more consistently in some regions.
Scientist 3: Fossil fuels are still necessary due to reliability and infrastructure.
34. Scientist 1 supports:
A. Fossil fuels
B. Wind energy
C. Solar energy
D. Nuclear waste
35. Main disagreement is about:
A. Water cycles
B. Best energy source
C. Weather patterns
D. Animal behavior
36. Scientist 2 believes wind energy is better because:
A. It is cheaper
B. It is more consistent in some areas
C. It is older
D. It is radioactive
37. Scientist 3 emphasizes:
A. Renewable energy only
B. Fossil fuels reliability
C. Solar panels only
D. Wind turbines only
38. All scientists agree that energy is:
A. Unnecessary
B. Important for society
C. Harmful always
D. Invisible
39. Which is renewable?
A. Coal
B. Oil
C. Wind
D. Gasoline
40. Best summary:
A. Only fossil fuels should be used
B. Only renewable energy is valid
C. Multiple energy sources have advantages and limitations
D. Energy choice does not matter