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
The area with no bacterial growth is likely due to the presence of the garlic extract, which has antimicrobial properties that inhibit or kill the bacteria.
Step 2
Explain which agar plate, shown in Figure 10, has the paper disc containing the 100 mg/cm² garlic extract.
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Agar plate C has the paper disc containing the 100 mg/cm² garlic extract because it shows the largest clear zone with no bacterial growth, indicating a stronger antibacterial effect compared to the lower concentrations.
Step 3
Give one way the student could improve their results.
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The student could use a control by including an agar plate without any garlic extract to compare the antibacterial effect.
Step 4
Calculate the area with no bacterial growth for agar plate B.
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Answer
The area of a circle is calculated using the formula:
A=extπr2
Substituting the values, we have:
A=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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The spreader is heated to sterilize it and kill any bacteria or microorganisms that may be present on the surface.
Step 6
Give two other ways of working safely with microorganisms.
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Disinfect the work surface or area to prevent contamination.
Work close to a Bunsen burner flame to create an updraft that helps to minimize the risk of airborne contamination.
