A comprehensive, block-period lesson bundle for 9th-grade biology covering enzyme structure and function. Includes guided notes, 4 collaborative data-analysis stations exploring factors affecting reaction rates, and a scaffolded Claim-Evidence-Reasoning (CER) activity with a quick exit ticket.
Liver cells contain high amounts of an enzyme called catalase, which protects cells by breaking down toxic cellular waste, hydrogen peroxide ($H_2O_2$), into harmless water and oxygen gas. In this experiment, the scientist keeps the amount of substrate ($H_2O_2$) completely unlimited and constant, but adds higher and higher concentrations of liver catalase to the reactions.
Reaction Rate vs Enzyme Concentration
0 (None) Medium High Reaction Rate 1% Conc. 2% Conc. 3% Conc. 4% Conc. Enzyme Concentration (Constant Excess Substrate)
Station 3 Group Prompts (Record answers on your Lab Sheet)
Analyze: Describe the overall trend shown in the graph. What is the mathematical relationship between enzyme concentration and reaction rate under these conditions?
Explain: Why does adding more enzyme continuously speed up the reaction rate in this specific experiment? (Hint: Read the X-axis label carefully!)
Predict: What would happen to the line on this graph if the substrate ($H_2O_2$) was NOT unlimited, but was a small, limited amount?
Enzyme Essentials: Active Learning Challenge Station Card 3 of 4
Lab Station 4
Busy Binding: Substrate Conc.
Factor D: Substrate Saturation
Scenario: Plant Cellulase
Plants are made of tough fiber called cellulose. Fungi release an enzyme called cellulase to digest this fiber. In an industry test, scientists kept a fixed, constant amount of cellulase enzymes inside four reaction chambers, but added increasingly higher amounts of substrate (cellulose) to each chamber to see how fast cellulose would break down.
Reaction Rate vs Substrate Concentration
0 (None) Medium High Reaction Rate 1g Substrate 2g Substrate 3g Substrate 4g Substrate Substrate Concentration (Constant Limited Enzymes) Saturation Point (Sites Full)
Station 4 Group Prompts (Record answers on your Lab Sheet)
Explain: Why does the reaction rate initially speed up from 0g to 2g of substrate?
Analyze: Why does the reaction rate flatten out (plateau) completely after 2g, remaining completely constant even when we add up to 4g of substrate?
Predict: What could scientists add to the reaction chamber at 4g of substrate to make the reaction rate increase again? Explain your reasoning!
Enzyme Essentials: Active Learning Challenge Station Card 4 of 4
Claim-Evidence-Reasoning
Real-World Scientific Explanation Practice
Name: ______________________
The Medical Mystery: Raising Stomach pH
A patient has been taking a strong anti-acid medication to treat acid reflux. While the medicine stopped the reflux, the patient is now experiencing severe stomach cramps, bloating, and constant digestive fatigue. Diagnostic testing reveals that the pH of the patient's stomach fluids has increased from pH 2 to pH 6.5.
Prompt: Write a Claim-Evidence-Reasoning response explaining how this change in stomach pH affects the patient's ability to digest proteins.
1. Claim (1-2 sentences)
Direct answer to the scientific prompt
2. Evidence (2-3 sentences)
Specific data & trends from Lab Station 2
3. Reasoning (3-4 sentences)
Biological explanation connecting Evidence to Claim (use "denature")
Enzyme Essentials: Active Learning Challenge Page 3 of 3
Enzyme Essentials Presentation Slide 5 of 8
The 4 Environmental Stations
Factors Affecting Enzymes
STATION 1
Temperature
Hot vs cold. What causes an enzyme's shape to completely unfold?
Amylase Data
STATION 2
pH Levels
Acids vs bases. How do stomach and digestive enzymes compare?
Pepsin vs Trypsin
STATION 3
Enzyme Conc.
Adding helpers with unlimited substrate supply. Does it speed up forever?
Liver Catalase
STATION 4
Substrate Conc.
Adding substrate to fixed enzymes. Why does the rate flatten out?
Plant Cellulase
Enzyme Essentials Presentation Slide 6 of 8
Writing Your CER: Stomach Mystery
Claim-Evidence-Reasoning
Claim
A direct statement that answers the question. Keep it clear, active, and concise (1-2 sentences).
Evidence
Your concrete data. Pull numbers, optimal peaks, or trends directly from Station 2 (pH curves) to support your claim.
Reasoning
Connect your evidence back to the claim. Use scientific concepts like "denaturing" and active site shapes to explain the "why".
THE SCENARIO
Patient pH rises from 2 to 6.5
The patient took strong acid reflux medicine, altering their stomach environment. Now, they are suffering from severe bloating and can't digest protein.
Write your CER on Page 3 of the packet!
Enzyme Essentials Presentation Slide 7 of 8
Closing & Exit Ticket
Wrapping Up
Great job today, Biologists!
Please wrap up your data tables and complete your Claim-Evidence-Reasoning response.
When finished with the CER, move back to your original seats to complete the independent Exit Ticket.
CHECKLIST FOR DISMISSAL
All 4 Stations filled out on Recorder
Stomach pH CER completely written
5-Min Exit Ticket completed & torn off
Enzyme Essentials Presentation Slide 8 of 8
Speaker
Enzyme Essentials Teacher Resource Page 1 of 2
Teacher Resource
Enzyme Essentials Keys
Handout Solutions & Grading Guidance
Block Period (90 Mins)
Guided Notes Keys
• Reactants/Products: Reactants & Products
• Energy: Activation Energy
• Speeds up / lowering: Speed up / Lowering
• Catalysts/Proteins: Proteins / Biological Catalysts
• Substrates: Reactants that enzymes bind to
• Active site: The pocket on enzyme
• Lock and Key: Perfectly specific model fit
• Step 1 Label: Substrate & Enzyme
• Step 2 Label: Enzyme-Substrate Complex
• Step 3 Label: Products Released
Exit Ticket Answers
Q1: Boiling thermal energy causes the protein folds of salivary amylase to break and unfold (denature), changing the active site's shape so it can no longer bind the lactose substrate.
Q2: Lowering activation energy (3rd choice) Q3: The shape of the active site (2nd choice)
Stomach pH CER Exemplar & Rubric
Standard Exemplar Response:
Claim: The increased stomach pH from 2 to 6.5 stops the digestion of proteins because the digestive enzyme pepsin becomes inactive and nonfunctional.
Evidence: According to the graph in Station 2, Pepsin works best in extremely acidic environments, showing high reaction rates peaking exactly at pH 2. When pH increases to pH 5 and above, pepsin's rate of reaction crashes to zero, leaving it completely nonfunctional.
Reasoning: Enzymes are folded proteins with a specific active site shape that matches their substrate. Pepsin's structure is optimized for acid. Raising the pH to 6.5 changes the hydrogen ion concentration, disrupting chemical bonds. This forces pepsin to unfold and lose its shape, a process called denaturing. Once denatured, the active site can no longer bind proteins, preventing digestion and leading to cramping.
