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Questions and Answers
What does a blue-black color change indicate when iodine is added to the solution?
What does a blue-black color change indicate when iodine is added to the solution?
The reaction time of the enzyme activity decreases as the temperature increases.
The reaction time of the enzyme activity decreases as the temperature increases.
True
What is the role of amylase in the investigation?
What is the role of amylase in the investigation?
To break down starch into simpler sugars.
The iodine solution is used to test for the presence of __________ in the reaction.
The iodine solution is used to test for the presence of __________ in the reaction.
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Match the following components of the experiment with their purposes:
Match the following components of the experiment with their purposes:
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What is the optimum pH for most enzymes?
What is the optimum pH for most enzymes?
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Enzymes produced in the stomach have an optimum pH of 9.
Enzymes produced in the stomach have an optimum pH of 9.
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What happens to an enzyme if the pH is moved too far from its optimum?
What happens to an enzyme if the pH is moved too far from its optimum?
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The optimum pH for enzymes produced in the duodenum is around _______.
The optimum pH for enzymes produced in the duodenum is around _______.
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Match the following enzymes to their corresponding optimum pH:
Match the following enzymes to their corresponding optimum pH:
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What are enzymes primarily classified as?
What are enzymes primarily classified as?
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Enzymes are permanently changed after they catalyze a chemical reaction.
Enzymes are permanently changed after they catalyze a chemical reaction.
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What is the function of enzymes in living organisms?
What is the function of enzymes in living organisms?
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Enzymes are biological catalysts made in __________.
Enzymes are biological catalysts made in __________.
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Match the following enzyme terms with their definitions:
Match the following enzyme terms with their definitions:
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Which of the following statements best describes enzyme specificity?
Which of the following statements best describes enzyme specificity?
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How long would it take to digest a meal without digestive enzymes?
How long would it take to digest a meal without digestive enzymes?
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The lock and key model illustrates how enzymes interact with their substrates.
The lock and key model illustrates how enzymes interact with their substrates.
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Which hypothesis explains the specificity of enzymes to their substrates?
Which hypothesis explains the specificity of enzymes to their substrates?
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Enzymes are consumed in the reaction and cannot catalyze further reactions.
Enzymes are consumed in the reaction and cannot catalyze further reactions.
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What forms when a substrate fits into the active site of an enzyme?
What forms when a substrate fits into the active site of an enzyme?
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The shape of an enzyme is important because it allows the formation of the _____ complex.
The shape of an enzyme is important because it allows the formation of the _____ complex.
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Match the following enzyme characteristics with their descriptions:
Match the following enzyme characteristics with their descriptions:
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What is the first step in enzyme action?
What is the first step in enzyme action?
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After products are formed, they fit perfectly back into the enzyme's active site.
After products are formed, they fit perfectly back into the enzyme's active site.
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What happens to an enzyme after it catalyzes a reaction?
What happens to an enzyme after it catalyzes a reaction?
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What is the optimum temperature for enzyme activity in the human body?
What is the optimum temperature for enzyme activity in the human body?
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Denaturation of enzymes is a reversible process.
Denaturation of enzymes is a reversible process.
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What happens to enzyme activity when the temperature is increased from 0⁰C to the optimum temperature?
What happens to enzyme activity when the temperature is increased from 0⁰C to the optimum temperature?
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Enzymes are ____, which have a specific shape critical for their function.
Enzymes are ____, which have a specific shape critical for their function.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What happens to an enzyme when it is heated beyond its optimum temperature?
What happens to an enzyme when it is heated beyond its optimum temperature?
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Low temperatures cause enzymes to become denatured.
Low temperatures cause enzymes to become denatured.
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What effect does increasing the temperature have on enzyme activity before reaching the optimum temperature?
What effect does increasing the temperature have on enzyme activity before reaching the optimum temperature?
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What indicates that starch has been digested in the experiment?
What indicates that starch has been digested in the experiment?
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The enzyme amylase works best in high pH environments.
The enzyme amylase works best in high pH environments.
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What role does the buffer solution play in the experiment?
What role does the buffer solution play in the experiment?
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The enzyme _________ is used in the experiment to digest starch.
The enzyme _________ is used in the experiment to digest starch.
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Match the following steps of the experiment with their purposes:
Match the following steps of the experiment with their purposes:
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Which of the following factors can affect enzyme activity?
Which of the following factors can affect enzyme activity?
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Enzymes function more effectively at lower temperatures.
Enzymes function more effectively at lower temperatures.
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How is the effectiveness of amylase at different pH levels measured?
How is the effectiveness of amylase at different pH levels measured?
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Study Notes
Enzymes
- Enzymes are biological catalysts
- Catalysts speed up the rate of a chemical reaction without being changed or used up in the reaction
- Enzymes are proteins
- Enzymes are essential for all living organisms as they maintain reaction speeds of all metabolic reactions (all the reactions that keep an organism alive) at a rate that can sustain life
- For example, without digestive enzymes, digesting a single meal would take around 2-3 weeks instead of around 4 hours.
Enzyme Action & Specificity
- Enzymes are specific to one particular substrate(s)
- The active site of the enzyme is complementary in shape to the substrate
- This is because the enzyme is a protein, and it has a specific 3-D shape
- This is known as the lock and key hypothesis
- When the substrate moves into the enzyme's active site they become known as the enzyme-substrate complex
- After the reaction occurs, the products leave the active site as they no longer fit
- The enzyme is unchanged and can catalyse further reactions
How Enzymes Work
- Enzymes and substrates randomly move about in the solution
- When an enzyme and substrate collide, and the substrate fits into the active site of the enzyme, an enzyme-substrate complex is formed
- A reaction occurs, and products form, which are released from the active site
- The enzyme is unchanged and ready to catalyse further reactions
Enzyme Investigations: Effect of Temperature on Amylase
- Starch solution is heated to a set temperature
- Iodine is added to wells on a spotting tile
- Amylase is added to the starch solution and mixed
- Every minute, droplets of the solution are added to a new well of iodine solution
- This is repeated until the iodine stops turning blue-black (meaning there's no more starch left/it has been completely broken down)
- The time taken for the reaction to complete is recorded
- The experiment is repeated at different temperatures
- The quicker the reaction is completed, the faster the enzyme is working
Enzyme Investigations: Effect of pH on Amylase
- Single drops of iodine solution are placed on a tile
- A test tube is labelled with the pH to be tested
- 2cm³ of amylase is placed in the test tube using a syringe
- 1cm³ of buffer solution is added to the test tube
- 2cm³ of starch solution is added to the mixture, and a stopwatch is started
- After 10 seconds a drop of the mixture is placed on the first drop of iodine. This should turn blue-black.
- This is repeated every 10 seconds until iodine solution remains orange-brown
- The experiment is repeated at different pH values
- The shorter the time taken for the iodine to remain orange-brown, the better the enzyme is working at that pH.
Enzymes & Temperature (Extended Tier Only)
- Enzymes are proteins with a specific shape held in place by bonds
- This specific shape is crucial for the active site to ensure the substrate fits
- Enzymes work fastest at their optimum temperature. For humans, this is 37°C
- Heating to temperatures beyond the optimum breaks the bonds holding the enzyme together, causing it to lose its shape—this is called denaturation
- Substrates cannot fit into denatured enzymes' distorted active sites because their shape is lost
- Denaturation is irreversible.
- Once denatured, enzymes cannot regain their proper shape or activity
Enzymes & pH (Extended Tier Only)
- Most enzymes have a pH optimum of 7
- Some have different optimum pHs due to their production environment (e.g., stomach enzymes have a lower pH optimum)
- If the pH is too high or too low, it can destroy bonds that hold the amino acid chain together, changing the shape of the active site
- This will cause the substrate to not fit into the active site, reducing enzyme activity
- Changing the pH too far from the optimum will cause denaturation of the enzyme.
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Description
Test your understanding of enzyme activity, their roles, and the effects of pH and temperature on their function. This quiz covers key concepts such as the function of amylase, the significance of iodine in experiments, and the optimum conditions for enzyme activity. Challenge yourself with matching components of enzyme reactions and understanding the broader implications of enzymes in biology.
