Enzyme Temperature Investigation

Overview

This practical develops students’ understanding of how cell structures and biochemical processes support life. In groups, students investigate how temperature affects catalase activity using potato tissue and hydrogen peroxide, then use repeated measurements to identify patterns, anomalies, denaturation and optimum conditions.

Learning intentions

Students will:

• explain how enzyme activity changes as temperature changes
• plan and conduct a controlled investigation with repeated trials
• identify independent, dependent and controlled variables
• process results and relate evidence to enzyme shape, denaturation and optimum conditions
• communicate a scientific conclusion supported by data

Success criteria

• I can state the variables in the investigation and explain how controls improve validity.
• I can collect repeated measurements safely and record units consistently.
• I can identify an anomalous result and justify whether it should be investigated or excluded.
• I can use evidence to explain the effect of temperature on enzyme activity, including denaturation.

Curriculum links

• Students explain how cell structures enable biological processes needed for life, including biochemical processes.
• Students explain how cells, tissues and systems contribute to complex multicellular organisms, including the role of specialised cell processes.
• Students identify the components of living things and their functions, including enzymes as biological components that support life processes.

Lesson structure (60 minutes)

1. 0–5 min · Hook and retrieval. Teacher displays a reaction comparison and asks, “Why might the same enzyme work quickly in one condition but slowly in another?” using the hook and retrieval slides. Students answer individually, then recall the meaning of enzyme, active site, substrate and denaturation.

2. 5–13 min · Investigation briefing. Teacher uses the investigation overview slides to model the reaction between catalase in potato and hydrogen peroxide, define temperature as the independent variable and foam height after a fixed time as the dependent variable, and explain that foam is an indirect measure of oxygen production. Students annotate the enzyme investigation worksheet with the research question, prediction, variables and controls. Establish temperature conditions such as ice bath, room temperature, 30°C, 40°C, 50°C and 60°C, adjusting to available equipment.

3. 13–20 min · Safety and method check. Teacher demonstrates the method and checks understanding: use goggles, tie back hair, avoid skin and eye contact with hydrogen peroxide, use tongs for warm equipment, and report spills immediately. Students form seven groups of five, assign roles, and use the worksheet to sequence the procedure and predict possible sources of error. Each group prepares potato pieces of similar size, labelled test tubes, a thermometer or temperature probe, hydrogen peroxide and a water bath or ice bath.

4. 20–40 min · Controlled practical investigation. Teacher circulates, checks temperatures and reinforces one-variable-at-a-time testing; use the relevant instructions and timing prompts in the practical procedure slides. Students equilibrate potato and hydrogen peroxide to the selected temperature, combine equal volumes, measure foam height after the same reaction time, and repeat each condition at least three times where equipment allows. Students record all raw data, including unexpected results, rather than deleting data during collection.

5. 40–50 min · Processing and analysis. Teacher pauses groups to compare data quality and displays the data analysis and anomaly slides. Students calculate a mean for each temperature, plot temperature against mean foam height, circle or annotate anomalous results, and discuss whether the anomaly may result from measurement error, unequal potato pieces, temperature drift, mixing differences or genuine biological variation. Students identify the likely optimum temperature from their group data.

6. 50–57 min · Evidence-based explanation. Teacher leads a whole-class discussion connecting the graph to enzyme-substrate interactions: increasing temperature initially increases particle movement and successful collisions; above the optimum, bonds maintaining enzyme shape can be disrupted, changing the active site and reducing activity. Students complete the worksheet conclusion using the structure “The data show… This is because… The evidence is…”, and compare results with another group.

7. 57–60 min · Exit assessment. Teacher displays the final prompt in the plenary slides and collects the completed response. Students answer: “A group records very low activity at 60°C. Explain why this may occur and name one improvement that would increase confidence in the conclusion.”

Resources

• Slide deck: hook, retrieval, investigation briefing, safety, practical procedure, data analysis, anomaly discussion and plenary
• Worksheet: investigation question, variables, risk check, method, raw results table, mean calculations, graph and conclusion prompts
• Potato cylinders or similarly sized potato pieces
• Dilute hydrogen peroxide solution and labelled test tubes
• Test-tube racks, measuring cylinders or syringes, thermometers and stopwatches
• Ice bath and water baths or beakers at several controlled temperatures
• Goggles, gloves if required, tongs, paper towel and spill-response materials
• Electronic balance or ruler for standardising potato pieces, if available

Assessment

• Check students’ variable identification, predictions and safety decisions before they begin.
• During the practical, assess whether groups maintain controlled volumes, temperatures, reaction times and potato size, and whether they complete appropriate repeats.
• Use the graph, anomaly justification and exit response to assess understanding of data reliability, optimum conditions and denaturation.

Differentiation

• Provide a partially completed method, a variables word bank and sentence starters such as “The independent variable is…” and “Activity decreases above… because…”.
• Allocate practical roles—equipment manager, temperature monitor, timer, recorder and safety checker—to support participation in groups of five.
• Provide pre-labelled equipment, visual procedure steps and a digital or printed graph template for students requiring executive-function or fine-motor support.
• Extend capable students by asking them to compare group means, calculate a range or percentage change, evaluate whether foam height is a valid measure of enzyme activity, and propose a follow-up investigation using pH or substrate concentration.
• Support EAL/D learners with diagrams, explicit modelling of “optimum”, “anomalous” and “denaturation”, and structured partner talk before written explanations.