Week 5 — Reading an Enzyme Experiment: The Catalase Lab Report — Traditional alternative (no AI)

Instructors: publish this instead of the adaptive version if you prefer, and unpublish or delete the adaptive one.

Assignment 5 of the term — read an enzyme experiment from its numbers to its conclusion and explain it to someone new to biology.

This week you learned that a cell captures and transfers energy and never makes it, and that the enzymes running its chemistry speed up toward an optimum and stop when heat destroys their shape. In this assignment you work four short problems on one small enzyme experiment, interpret each one, and explain the result to someone who has never studied biology. This week's lecture tutorial, quiz, discussion, and Biology Lab & Inquiry practise the same ideas from other angles.

The task

Pieces of potato were held at four temperatures, dropped into hydrogen peroxide, and the foam height was measured after 60 seconds. Catalase in the potato splits hydrogen peroxide into water and oxygen, and the oxygen makes the foam. The catalase and temperature example is an illustrative dataset constructed for this course (not real data). Three trials were run at each temperature:

• cold, about 5 °C: 1, 2, and 3 cm;
• room, about 22 °C: 4, 5, and 6 cm;
• body, about 37 °C: 9, 10, and 11 cm;
• boiled, about 100 °C and cooled before testing: 0, 0, and 0 cm.

The averages are 2 cm cold, 5 cm room, 10 cm body, and 0 cm boiled.

Work these four problems, showing your arithmetic:

1. Add the three body-temperature trials from the catalase and temperature example (9, 10, and 11 cm of foam). What is the total, in centimeters?
2. The three cold trials total 6 cm of foam. Divide by the number of trials (3). What is the cold average, in centimeters?
3. The body-temperature average is 10 cm and the cold average is 2 cm. How many times the cold foam is the body-temperature foam?
4. The largest body-temperature trial made 11 cm of foam and the smallest made 9 cm. What is the range of the body-temperature trials, in centimeters?

Beside each answer, add one brief interpretation:

• Problem 1: name the independent variable and the dependent variable, and explain why the experiment runs three trials per condition instead of one.
• Problem 2: explain why the cold sample was slowed rather than denatured, and predict what would happen to its foam if the cold potato were warmed back up.
• Problem 3: explain which temperature sits nearest the enzyme's optimum and why the boiled average of 0 cm shows that hotter is not always faster, and name one controlled variable the design must hold steady.
• Problem 4: compare the spread of the trials with the climb of the averages from 2 to 10 cm, then write a one-sentence conclusion that uses "supports" or "fails to support" rather than "proves," and name one result that would have counted against the hypothesis.

Explain it to a non-expert

Your younger cousin watches the boiled potato sit in the peroxide without a single bubble and asks, "Did the boiling kill the fizz, or did it get too cold afterward?" Write a 3–5 sentence message that explains what the test changed and what it measured, reports the result in everyday words, and names one limit, including that these numbers are illustrative and that one small test can support a claim but never prove it. Explain any technical term in everyday words. More than one good answer is possible.

For a different, ungraded example, imagine a cyclist who tests whether a lighter wheel shortens a daily ride. Model answer: "I rode the same route on calm mornings, changing only the wheel, and timed each ride. The rides with the lighter wheel were a little quicker each time. Everything else about the ride stayed the same, so the wheel is the likely reason. I only tried it a handful of times, so the result supports the idea but does not prove it; a windy week might change things."

Use that pattern for the catalase experiment, with your own wording and evidence.

Show your arithmetic. A reader should be able to reproduce every number you report from the twelve foam heights without guessing which values or steps you used.

Deliverables

Submit a single lab report containing:

• the four answers, each with the arithmetic shown and the brief interpretation the task names for that problem;
• your message to your cousin, explaining what the test changed and measured, the result in everyday words, and one limit; and
• a one-line restatement of the twelve foam heights you used, so your results are reproducible.

Keep it to roughly one page. Clear and correct beats long.

Choose how you show it. Present your report as written text, or as a recorded audio or video explanation of about three minutes with a transcript, or as a labelled sketch of the four averages with a short note. Every form is graded by the same scoring criteria. Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text.

How you'll be graded

The full analytic rubric is attached to this assignment in Canvas.

Academic integrity and AI use

This version is designed to be completed without AI: do the computations, the interpretations, and the writing yourself, without a chatbot or other AI tool. You may use a calculator or a spreadsheet for the arithmetic. Submitting AI-generated work as your own, or copying another student's work, is an integrity violation under the course policy.

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