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2.2 Animal tissues, organs and organ systems

2.2 Animal tissues, organs and organ systems

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Question 25

Amylase is an enzyme that digests starch in the human body.

a.

Amylase is a biological polymer. Name the monomer (smaller molecule) that forms this polymer.

[1]
b.

Name two organs in the human digestive system that produce amylase.

[2]
c.

Explain how amylase breaks down starch. Answer in terms of the 'lock and key theory'.

[3]
d.

A student investigated the effect of pH on the activity of amylase.

The student used the following method:

  1. Measure 4 cm34\text{ cm}^34 cm3 of starch solution, 1 cm31\text{ cm}^31 cm3 of buffer solution (to maintain pH), and 0.5 cm30.5\text{ cm}^30.5 cm3 of iodine solution into a test tube. The solution turns blue-black.
  2. Place this test tube and a separate tube containing 2 cm32\text{ cm}^32 cm3 of amylase solution into a water bath at 40∘C40^\circ\text{C}40∘C for 6 minutes.
  3. Add the amylase solution to the starch mixture, stir, and start a stopwatch.
  4. Record the time taken for the blue-black colour to disappear.
  5. Repeat the experiment using buffer solutions of different pH values.

Why did the student leave the tubes in the water bath for 6 minutes before mixing them?

[1]
e.

Name two control variables the student kept constant in this investigation.

[2]
f.

Explain why the blue-black colour disappears when amylase breaks down the starch.

[2]
Markscheme

2.2 Animal tissues, organs and organ systems Questions

  1. GCSE
  2. /Biology
  3. /2.2 Animal tissues, organs and organ systems

44 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.

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