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6 (a) Lactase is an enzyme that breaks down lactose into glucose and galactose - Edexcel - GCSE Biology - Question 6 - 2019 - Paper 1
Question 6
6 (a) Lactase is an enzyme that breaks down lactose into glucose and galactose. A student made some alginate beads containing lactase. The student added 10 beads to... show full transcript
Worked Solution & Example Answer:6 (a) Lactase is an enzyme that breaks down lactose into glucose and galactose - Edexcel - GCSE Biology - Question 6 - 2019 - Paper 1
Step 1
What is the rate of reaction for 25 beads?
Answer
To calculate the rate of reaction for 25 beads, we use the formula:
ext{Rate} = rac{ ext{Change in product}}{ ext{Time taken}}
From the results, the time taken to produce glucose with 25 beads is 120 seconds. Thus, the rate of reaction can be understood as:
- For 25 beads, if we assume the total glucose produced is the same for all tests, then:
- Let's say the total glucose produced is X.
Using the time taken:
ext{Rate} = rac{X}{120 ext{s}}
Since we need a unit of s⁻¹, we convert:
rac{X}{120} = 0.008 ext{s}^{-1} \text{ (considering X for differential units)}.
Thus, the correct answer is A 0.008 s⁻¹.
Step 2
Explain the conclusion that can be made from these results.
Answer
The results show that as the number of beads containing lactase increases, the time taken to produce glucose decreases. This indicates that the rate of reaction is positively correlated with the concentration of the enzyme (in beads). More enzymatic beads lead to more active sites available for the substrate (lactose), allowing for a faster breakdown into glucose and galactose. It suggests that increasing the enzyme quantity enhances the reaction rate until substrate limitation, suggesting optimal enzyme activity.
Step 3
Explain why the same volume of lactose solution was used for each test.
Answer
Using the same volume of lactose solution in each test ensures consistency and fairness in the experiment. This control allows for a valid comparison of the rate of reaction across different trials with varying numbers of alginate beads. Variations in substrate volume could introduce additional variables affecting the rate of glucose production, making it difficult to determine the specific impact of the enzyme concentration (beads).
Step 4
Devise a method to find the optimum temperature for the enzyme lactase.
Answer
To determine the optimum temperature for lactase, follow these steps:
- Prepare a series of test tubes with equal amounts of lactose solution and equal numbers of alginate beads containing lactase.
- Place each test tube in a water bath set to different temperatures, such as 0°C, 20°C, 30°C, 37°C (body temperature), 50°C, and 60°C.
- Allow the test tubes to equilibrate for 5-10 minutes to stabilize the temperature.
- Start a timer and measure the time taken to produce a specific amount of glucose (for instance, use colorimetric methods to quantify glucose production).
- Record the time taken for each temperature and calculate the reaction rate.
- Plot a graph of reaction rate against temperature. The peak of the graph will indicate the optimum temperature for lactase activity.