A student investigated the antibiotic properties of garlic - Edexcel - GCSE Biology - Question 5 - 2023 - Paper 1
Question 5
A student investigated the antibiotic properties of garlic.
Bacteria were spread on an agar plate.
A paper disc was soaked in garlic extract and placed on this agar ... show full transcript
Worked Solution & Example Answer:A student investigated the antibiotic properties of garlic - Edexcel - GCSE Biology - Question 5 - 2023 - Paper 1
Step 1
Suggest why there is an area with no bacterial growth.
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Answer
Bacteria are killed by the garlic extract.
Step 2
Explain which agar plate, shown in Figure 10, has the paper disc containing the 100 mg/cm³ garlic extract.
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Answer
Agar plate C has the 100 mg/cm³ concentration of garlic extract because it shows the largest area of no bacterial growth compared to plates A and B.
Step 3
Give one way the student could improve their results.
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Answer
One way the student could improve their results is to use a control.
Step 4
Calculate the area with no bacterial growth for agar plate B.
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Answer
The area can be calculated using the formula for the area of a circle:
ext{area} = rac{22}{7} imes r^2
Given that the radius (r) is 5 mm:
extarea=3.14imes(5extmm)2=3.14imes25=78.5extmm2
Step 5
State the reason for heating the spreader in the flame of a Bunsen burner before use.
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Answer
To sterilise it to kill bacteria and microorganisms.
Step 6
Give two other ways of working safely with microorganisms.
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