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4.1 Evolution and natural selection

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Question 9
F

A scientist spread one species of bacteria evenly over the surface of a nutrient agar plate. She placed a paper disc soaked in an antibiotic in the centre of the plate.

She incubated the plate for two days.

The Figure shows the plate after two days.

Figure

image

a.

Explain why there is a clear zone around the paper disc.

[2]
b.

Two colonies of bacteria, labelled X, grew inside the clear zone. Explain why.

[2]
c.

The scientist took bacteria from one colony X and spread them on a new agar plate. She placed a paper disc soaked in the same antibiotic in the centre of this plate. Predict what the new plate would look like after two days. Explain your answer.

[2]
Markscheme

4.1 Evolution and natural selection Questions

  1. GCSE
  2. /Biology
  3. /4.1 Evolution and natural selection

44 exam-style questions on Edexcel GCSE Biology 4.1 Evolution and natural selection, covering 4.1.1 Work of Darwin and Wallace and 4.1.2 Resistant organisms and evolution. Each one has a worked solution and a mark scheme showing where the marks go.

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