GCSE Edexcel Biology Combined Science Enzymes: A student mixed 10 cm³ of starch

Question

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 and for glucose every 30 seconds.

Figure 5 shows the results.

Figure 5

time in seconds | starch detected | glucose detected
0                | Yes              | No
30               | Yes              | No
60               | Yes              | No
90               | Yes              | No
120              | No               | Yes
150              | No               | Yes
180              | No               | Yes

(i) Give one reason for the result at 150 seconds.

(ii) Another student repeated the investigation with the same volumes of solutions and at the same temperature of 25°C. Give two other variables that would need to be controlled in the investigation.

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 Combined Science - Question 4 - 2020 - Paper 1

Worked Solution & Example Answer: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 Combined Science - Question 4 - 2020 - Paper 1

Give one reason for the result at 150 seconds.

Give two other variables that would need to be controlled in the investigation.

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