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5.3 Immune system and medicines

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Question 25
H

Two antibiotic discs each have a radius of 3 mm. Their circular clear zones, including the discs, have radii of 5 mm and 7 mm.

What is the ratio of the smaller clear agar area to the larger clear agar area, excluding both discs?

Use A=πr2A=\pi r^2A=πr2.

[1]
A

5:75:75:7

B

2:52:52:5

C

25:4925:4925:49

D

1:21:21:2

Markscheme

5.3 Immune system and medicines Questions

  1. GCSE
  2. /Biology
  3. /5.3 Immune system and medicines

45 exam-style questions on Edexcel GCSE Biology 5.3 Immune system and medicines, covering 5.3.1 The specific immune system, 5.3.2 Response to immunisation, 5.3.3 Advantages and disadvantages of immunisation, 5.3.4 Antibiotics and bacterial infections, 5.3.5 Aseptic techniques in culturing, 5.3.6 Cross-sectional areas of cultures, 5.3.7 Stages of developing new medicines, and 5.3.8 Production of monoclonal antibodies. Each one has a worked solution and a mark scheme showing where the marks go.

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