The diagram shows colonies of bacteria growing on two agar plates. Bacterium A Diameter = 6 cm Bacterium B Diameter = 2 cm What is the ratio of the area covered by bacterium A compared to the area covered by bacterium B? (The area of a circle = πr²) A 1:3 B 1:9 C 3:1 D 9:1 Your answer

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The diagram shows colonies of bacteria growing on two agar plates - OCR Gateway - GCSE Biology - Question 6 - 2021 - Paper 1

Question 6

The diagram shows colonies of bacteria growing on two agar plates. Bacterium A Diameter = 6 cm Bacterium B Diameter = 2 cm What is the ratio of the area covered... show full transcript

Worked Solution & Example Answer:The diagram shows colonies of bacteria growing on two agar plates - OCR Gateway - GCSE Biology - Question 6 - 2021 - Paper 1

Step 1

Calculate the area of Bacterium A

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Answer

The radius of Bacterium A is half of its diameter:

$r_A = \frac{6}{2} = 3 \text{ cm}$

The area covered by Bacterium A is given by the formula:

$A_A = \pi r_A^2 = \pi (3)^2 = 9\pi \text{ cm}^2$

Step 2

Calculate the area of Bacterium B

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Answer

The radius of Bacterium B is half of its diameter:

$r_B = \frac{2}{2} = 1 \text{ cm}$

The area covered by Bacterium B is:

$A_B = \pi r_B^2 = \pi (1)^2 = \pi \text{ cm}^2$

Step 3

Determine the ratio of areas

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Answer

The ratio of the areas covered by Bacterium A to Bacterium B is:

$\text{Ratio} = \frac{A_A}{A_B} = \frac{9\pi}{\pi} = 9:1$

Thus, the answer is D 9:1.

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The diagram shows colonies of bacteria growing on two agar plates - OCR Gateway - GCSE Biology - Question 6 - 2021 - Paper 1

Worked Solution & Example Answer:The diagram shows colonies of bacteria growing on two agar plates - OCR Gateway - GCSE Biology - Question 6 - 2021 - Paper 1

Calculate the area of Bacterium A

Calculate the area of Bacterium B

Determine the ratio of areas

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