6 A student mixed 10 cm³ of starch solution with 5 cm³ of amylase solution and kept the tube in a water bath at 25 °C - Edexcel - GCSE Biology - Question 6 - 2020 - Paper 1
Question 6
6 A student mixed 10 cm³ of starch solution with 5 cm³ of amylase solution and kept the tube in a water bath at 25 °C.
The student tested the solution for starch a... show full transcript
Worked Solution & Example Answer:6 A student mixed 10 cm³ of starch solution with 5 cm³ of amylase solution and kept the tube in a water bath at 25 °C - Edexcel - GCSE Biology - Question 6 - 2020 - Paper 1
Step 1
Give one reason for the result at 150 seconds.
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Answer
At 150 seconds, starch is no longer detected because amylase has fully broken down the starch into glucose, indicating that the reaction has reached completion.
Step 2
Give two other variables that would need to be controlled in the investigation.
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Answer
The temperature of the solutions should be kept constant at 25 °C to ensure accurate results.
The concentration of the starch solution should remain the same throughout the experiment to maintain consistency.
Step 3
Give one reason why this tube was included in their investigations.
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Answer
This tube was included to serve as a control, demonstrating that any glucose detected is due to the action of amylase on starch, and to rule out the presence of glucose from other sources.
Step 4
Devise a method the students could use to confirm the optimum pH for amylase.
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Answer
The students could set up a series of test tubes containing starch solution and different buffer solutions ranging from pH 5 to pH 8. They would then add a fixed amount of amylase to each tube and incubate them at 25 °C. After a set time, they would test for glucose presence with iodine and record the pH level at which glucose is produced in the shortest time.
Step 5
Explain why amylase is not produced in the stomach.
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Answer
Amylase is not produced in the stomach because the acidic environment (low pH) denatures the enzyme, rendering it inactive. Additionally, amylase is primarily produced in the salivary glands and pancreas, not in the stomach.
