18 Questions
What happens to the rate of enzyme activity as temperature increases?
Increases
How does moving too far away from the optimum pH affect enzyme activity?
Causes denaturation
What is the typical optimum pH for most enzymes?
pH 7
How does low temperature affect enzyme function?
Slows down enzyme activity
What effect does a high or low pH have on the bonds in enzyme proteins?
Breaks bonds
What happens if an enzyme moves away from its optimum pH?
Denaturation of the enzyme
What best describes the role of an enzyme?
A catalyst that speeds up reactions in cells, without being used up in the process.
What is a common feature of all catalysts?
They are not changed by the reaction
Which of the following correctly represents the effect of temperature on enzyme activity?
The higher the temperature, the higher the enzyme activity until the enzyme denatures
At what pH level would an enzyme likely denature?
pH 11 (very basic)
What happens to enzyme activity when it is denatured?
It decreases significantly
Which statement accurately describes the optimal pH for enzyme activity?
Each enzyme has a unique optimal pH at which it works best
What is the purpose of adding iodine solution in the enzyme investigation with amylase?
To test the enzyme activity by observing a color change
Why is it important to use different pH values in the enzyme investigation?
To observe how pH affects enzyme efficiency
What does it mean if the iodine solution remains orange brown after a short period in the enzyme investigation?
The enzyme is working optimally
What happens to enzymes when they denature?
They lose their shape and activity
Why is it important to start a stopwatch while mixing amylase and starch in the enzyme investigation?
To track the digestion process over time
What is the significance of observing a blue-black color in the iodine solution during the enzyme investigation?
It means that starch has been completely digested
Study Notes
Effect of Temperature on Enzyme Activity
- Increasing the temperature from 0°C to the optimum increases enzyme activity, as more energy leads to faster molecular movement and more collisions with substrate molecules.
- Low temperatures do not denature enzymes, but make them work slower.
Effect of pH on Enzyme Activity
- The optimum pH for most enzymes is 7, but some enzymes have a lower optimum pH (e.g., pH 2 in the stomach) or higher optimum pH (e.g., pH 8 or 9 in the duodenum).
- If the pH is too high or too low, the bonds holding the amino acid chain together can be destroyed, changing the active site shape and reducing enzyme activity.
- Moving too far away from the optimum pH can cause enzyme denaturation and stop activity.
Enzyme Investigations
- Amylase is an enzyme that digests starch into maltose.
- Iodine solution is used to test for starch.
- Investigating the effect of temperature on amylase:
- Starch solution is heated to a set temperature.
- Iodine is added to wells of a spotting tile.
- Amylase is added to the starch solution and mixed well.
- The time taken for the reaction to be completed is recorded.
- The experiment is repeated at different temperatures.
- Investigating the effect of pH on amylase:
- Place single drops of iodine solution in rows on the tile.
- Use buffer solutions of different pH values.
- Add amylase and starch solution to the buffer solution.
- Use a pipette to place drops of the mixture on the iodine solution.
- Repeat the experiment at different pH values.
Exam Tips
- Describing and explaining experimental results for enzyme experiments is a common type of exam question.
- To score high, relate the results to changes in the active site of the enzyme when denatured or to the amount of kinetic energy the molecules have at low temperatures.
Learn about how temperature impacts the activity of enzymes and the rate of reactions. Find out why increasing temperature can lead to a faster rate of reaction and how low temperatures affect enzyme function.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
