Diastase is an enzyme that breaks down starch into maltose. A sample of starch is treated with boiled diastase and left for 15 minutes. Samples of the mixture are then tested with iodine solution and with Benedict's solution. What is the correct result?

Biology

IGCSE&ALevel

CAIE

Exam No：9700_s25_qp_14 Year：2025 Question No：8

Answer:

Knowledge points:

2.1.1 describe and carry out the Benedict’s test for reducing sugars, the iodine test for starch, the emulsion test for lipids and the biuret test for proteins

2.1.2 describe and carry out a semi-quantitative Benedict’s test on a reducing sugar solution by standardising the test and using the results (time to first colour change or comparison to colour standards) to estimate the concentration

2.1.3 describe and carry out a test to identify the presence of non-reducing sugars, using acid hydrolysis and Benedict’s solution

3.1.1 state that enzymes are globular proteins that catalyse reactions inside cells (intracellular enzymes) or are secreted to catalyse reactions outside cells (extracellular enzymes)

3.1.2 explain the mode of action of enzymes in terms of an active site, enzyme–substrate complex, lowering of activation energy and enzyme specificity, including the lock-and-key hypothesis and the induced-fit hypothesis

3.1.3 investigate the progress of enzyme-catalysed reactions by measuring rates of formation of products using catalase and rates of disappearance of substrate using amylase

3.1.4 outline the use of a colorimeter for measuring the progress of enzyme-catalysed reactions that involve colour changes

Diastase is an enzyme that breaks down starch into maltose. A sample of starch is treated with boiled diastase and left for 15 minutes. Samples of the mixture are then tested with iodine solution and with Benedict's solution. What is the correct result?

Answer:

Knowledge points:

Solution:

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