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1.1 Cell structure

1.1 Cell structure

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Question 44
47%

A student investigated the effectiveness of three different antibiotics (X, Y, and Z) against a specific bacterium grown on an agar plate.

The student measured the diameter of the circular zone of inhibition (the clear area where no bacteria grew) around each antibiotic paper disc:

  • Antibiotic X: 18 mm18\text{ mm}18 mm
  • Antibiotic Y: 30 mm30\text{ mm}30 mm
  • Antibiotic Z: 12 mm12\text{ mm}12 mm
a.

Describe one aseptic technique the student should have used to prevent contamination of the agar plate when preparing this experiment.

[1]
b.

Which antibiotic is the most effective? Give a reason for your answer.

[2]
c.

Calculate the area of the zone of inhibition for antibiotic Y. Use π=3.14\pi = 3.14π=3.14. Give your answer to 1 decimal place and include the unit in your final answer.

[3]
d.

Suggest one way the student could improve the reliability of this investigation.

[1]
Markscheme

1.1 Cell structure Questions

  1. GCSE
  2. /Biology
  3. /1.1 Cell structure

163 exam-style questions on AQA GCSE Biology 1.1 Cell structure, covering 1.1.1 Eukaryotes and prokaryotes, 1.1.2 Animal and plant cells, 1.1.3 Cell specialisation, 1.1.4 Cell differentiation, 1.1.5 Microscopy, and 1.1.6 Culturing microorganisms. Each one has a worked solution and a mark scheme showing where the marks go.

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