Explain amylase digestion of starch
Use the Core product description of simple reducing sugars.
Section B7.4 · Chemical digestion
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Recall large and small nutrient molecules, cell membranes and enzyme specificity.
- Use the stated diagram keys and evidence; models are not to scale.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which substrate does amylase act on here?
What you will learn
- Use the Core product description of simple reducing sugars.
- Interpret product tests using the initial state and controls.
Match enzyme and substrate
Amylase catalyses breakdown of starch to simple reducing sugars. Starch is the substrate; amylase is the catalyst, not the sugar product. The Core statement does not require the learner to name every intermediate sugar.
Enzyme specificity matters: an amylase result for starch is not evidence that it also digests protein or fat. Use the right enzyme-substrate pair rather than treating all digestive enzymes as interchangeable.
Use controlled product evidence
A suitable teacher-supervised test can compare starch loss and appearance of reducing sugars with matched starting solutions and controls. A positive product test must be compared with any reducing sugar already present initially.
The Extended sequence names maltose and maltase later. Do not use the inaccurate shortcut that amylase alone performs both named stages from starch through maltose to glucose.
Sources for this lesson
Pause and explain
Which Core product description fits amylase action?
Worked example
A controlled starch-amylase mixture loses detected starch and develops reducing sugars absent initially. Interpret the evidence.
Show the worked solution
- Use both starting and final tests.
- Name amylase and starch.
- Infer formation of simpler reducing sugars.
Answer The controlled evidence supports amylase digestion of starch to simple reducing sugars.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Complete: amylase breaks ___ into ___.
Give me a hint
Name substrate and Core products.
Compare my reasoning
- Starch.
- Simple reducing sugars.
Starch into simple reducing sugars.
Look for these in your work
- Correct pair.
- Enzyme distinct from product.
A starch solution already tests positive for reducing sugars before amylase. Why is a positive final test alone weak evidence of new digestion?
Give me a hint
The product indicator was present initially.
Compare my reasoning
- Initial sugars may explain final positivity.
- Compare changes and matched controls.
The final positive result may reflect starting sugars; changes and controls are needed.
Look for these in your work
- Initial-state issue.
- Appropriate comparison.
A student adds amylase to protein and interprets no digestion as proof that all enzymes fail. Correct the reasoning.
Give me a hint
Specificity limits the test.
Compare my reasoning
- Amylase has the wrong substrate.
- Use the relevant protease comparison.
The result does not test all enzymes; amylase is specific to the starch pathway here.
Look for these in your work
- Specificity.
- No universal failure conclusion.
Common mistakes
- Amylase is not its own product.
- Initial sugar must be checked before inferring new production.
What can you explain now?
Which Core product description fits amylase action?
Compare with the explanation
Simple reducing sugars.
Use the required Core wording.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Write the correct Core enzyme-substrate-product relationship.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.