Unit Checkpoint
Unit Overview
This checkpoint tests your mastery of all ACT Science Reasoning skills covered in this unit. Before proceeding, make sure you have completed all previous lessons:
- Lesson 1 - Data Representation: Reading and interpreting scientific data displays
- Lesson 2 - Research Summaries: Understanding experimental procedures and conclusions
- Lesson 3 - Investigation Lab: Experimental design and variable identification
- Lesson 4 - Data and Graphs: Advanced graph interpretation and analysis
- Lesson 5 - CER Writing: Claim-Evidence-Reasoning framework
ACT Science Section Format
The ACT Science section includes:
- 40 questions in 35 minutes
- 6-7 passages with data, experiments, or conflicting viewpoints
- Average of about 5-7 questions per passage
- Time target: approximately 5 minutes per passage
Key Skills for Success
- Quick and accurate data reading from graphs, tables, and figures
- Understanding experimental design and variable relationships
- Evaluating conclusions based on evidence
- Identifying trends, patterns, and relationships
- Comparing and contrasting different experiments or viewpoints
Passage-Based Practice
Read the following passage and answer the questions that follow.
Passage: Enzyme Activity Study
Scientists investigated how temperature affects the activity of amylase, an enzyme that breaks down starch. They measured enzyme activity by recording the time required to completely digest a standard amount of starch at different temperatures.
Experiment 1: Amylase was tested at temperatures from 10C to 70C. Results are shown in Table 1.
| Temperature (C) | Time to Digest Starch (seconds) | Relative Activity |
|---|---|---|
| 10 | 180 | 22% |
| 20 | 90 | 44% |
| 30 | 55 | 73% |
| 37 | 40 | 100% |
| 50 | 65 | 62% |
| 60 | 150 | 27% |
| 70 | No digestion | 0% |
Experiment 2: Researchers tested whether the loss of activity at high temperatures was reversible. Amylase samples were heated to 50C, 60C, or 70C for 10 minutes, then cooled to 37C and tested.
| Pre-heating Temperature | Activity After Cooling to 37C |
|---|---|
| 50C | 95% |
| 60C | 45% |
| 70C | 5% |
Practice Questions
1. Based on Table 1, at what temperature does amylase show maximum activity?
A. 10C B. 30C C. 37C D. 50C
2. According to the data, which statement best describes the relationship between temperature and digestion time between 10C and 37C?
A. As temperature increases, digestion time increases
B. As temperature increases, digestion time decreases
C. Temperature has no effect on digestion time
D. Digestion time is constant regardless of temperature
3. What is the independent variable in Experiment 1?
A. Time to digest starch
B. Amount of starch
C. Temperature
D. Relative activity
4. Based on Experiment 2, heating amylase to which temperature causes the most permanent damage?
A. 37C B. 50C C. 60C D. 70C
5. A student claims that "enzyme activity always increases with temperature." Does the data support this claim?
A. Yes, activity increased at every temperature tested
B. No, activity peaked at 37C and decreased at higher temperatures
C. Yes, the fastest digestion time occurred at the highest temperature
D. No, activity was highest at the lowest temperature
6. What is the purpose of Experiment 2?
A. To find the optimal temperature for enzyme activity
B. To determine if high-temperature damage is reversible
C. To measure how quickly enzymes digest starch
D. To compare different enzymes
7. If the experiment were repeated at 45C, the digestion time would most likely be:
A. Less than 40 seconds
B. Between 40 and 55 seconds
C. Between 55 and 65 seconds
D. Greater than 90 seconds
8. Based on both experiments, at 70C the enzyme most likely:
A. Works faster than at any other temperature
B. Is temporarily slowed but recovers fully when cooled
C. Is permanently denatured and loses its function
D. Converts to a different type of enzyme
9. Which control variable should the researchers keep constant across all trials?
A. Temperature
B. Amount of starch
C. Time to digest
D. Relative activity
10. Using the CER framework, write a paragraph explaining why 37C is likely the optimal temperature for human amylase. Include a claim, specific evidence from the data, and reasoning that connects to biology.
11. A researcher proposes testing amylase activity at 80C and 90C. Based on the data trends, predict the results and explain your reasoning.
12. If a student wanted to improve Experiment 1, which modification would increase reliability?
A. Test only one temperature
B. Use a different enzyme
C. Perform multiple trials at each temperature
D. Decrease the amount of starch used
Answer Key
Check your answers below.
Question 1
C. 37C - This shows 100% relative activity and the fastest digestion time (40 seconds).
Question 2
B. As temperature increases, digestion time decreases - Time dropped from 180s at 10C to 40s at 37C.
Question 3
C. Temperature - This is what the researchers deliberately changed to observe its effect.
Question 4
D. 70C - Only 5% activity recovered after cooling, indicating severe permanent damage.
Question 5
B. No, activity peaked at 37C and decreased at higher temperatures - The claim overclaims; activity clearly declined after 37C.
Question 6
B. To determine if high-temperature damage is reversible - The experiment tested recovery after heating.
Question 7
B. Between 40 and 55 seconds - 45C falls between 37C (40s) and 50C (65s); interpolation suggests a value in between, closer to 40s.
Question 8
C. Is permanently denatured and loses its function - Zero activity at 70C plus only 5% recovery indicates permanent structural damage.
Question 9
B. Amount of starch - The starch amount must be constant to fairly compare digestion times across temperatures.
Question 10
Sample CER Response: Claim: 37C is the optimal temperature for human amylase because it matches human body temperature. Evidence: At 37C, amylase showed 100% relative activity and the fastest digestion time of 40 seconds. Reasoning: Enzymes have evolved to function best at the temperature of their environment. Human body temperature is approximately 37C, so human amylase has adapted to work most efficiently at this temperature. The enzyme's active site has the optimal shape at this temperature to bind with starch molecules.
Question 11
At 80C and 90C, the enzyme would likely show zero activity, similar to 70C. The trend shows activity declining sharply above 50C and reaching zero at 70C. Higher temperatures would cause even more severe protein denaturation, and based on Experiment 2, the damage would be essentially irreversible.
Question 12
C. Perform multiple trials at each temperature - Replication increases reliability by reducing the impact of random error.
Next Steps
- Review any questions you missed and identify which skill needs more practice
- Return to specific lessons if you need to strengthen particular skills
- Practice with full-length ACT Science sections to build speed and stamina
- Congratulations on completing the ACT Science Reasoning unit!