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.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The area with no bacterial growth suggests that the garlic extract has antibiotic properties which effectively killed the bacteria in that region.
Step 2
Explain which agar plate, shown in Figure 10, has the paper disc containing the 100 mg/cm² garlic extract.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Agar plate C is the one with the paper disc containing the 100 mg/cm² garlic extract, as it shows the largest clear zone with no microbial growth, indicating the highest antibacterial activity.
Step 3
Give one way the student could improve their results.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
One way the student could improve their results is by ensuring that the agar plates are incubated at the same temperature during the experiment.
Step 4
Calculate the area with no bacterial growth for agar plate B.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To find the area, we use the formula for the area of a circle:
ext{Area} = rac{22}{7} r^2
Substituting the radius (r = 5 mm):
ext{Area} = rac{22}{7} imes (5^2) = rac{22}{7} imes 25 = 78.5 ext{ mm}^2
Step 5
State the reason for heating the spreader in the flame of a Bunsen burner before use.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The spreader is heated to sterilise it, which helps to eliminate any bacteria or microorganisms present on the spreader.
Step 6
Give two other ways of working safely with microorganisms.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Disinfect the work surface before starting the experiment.
Use protective gloves or a face mask when handling microorganisms.
