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Figure 10 shows part of a method used to produce a bacterial culture on a Petri dish - Edexcel - GCSE Biology - Question 10 - 2022 - Paper 1
Question 10
Figure 10 shows part of a method used to produce a bacterial culture on a Petri dish. Step 1. Sterilise Petri dish and agar before use. Step 2. Pass inoculating loo... show full transcript
Worked Solution & Example Answer:Figure 10 shows part of a method used to produce a bacterial culture on a Petri dish - Edexcel - GCSE Biology - Question 10 - 2022 - Paper 1
Step 1
State why step 1 and step 2 are necessary.
Answer
Step 1 is necessary to sterilise the Petri dish and agar to eliminate any potential contaminants that could affect the results of the bacterial culture. This helps ensure that only the intended bacteria grow in the culture, preventing misleading conclusions.
Step 2 is essential because passing the inoculating loop through a flame sterilises it by killing any microbes that might be present. This step further prevents contamination of the bacterial sample and the culture, allowing for a pure growth of the desired bacteria.
Step 2
Give one reason why step 3 is included.
Answer
Step 3, allowing the inoculating loop to cool, is included to prevent the heat from the loop from killing the bacteria when collecting the sample. If the loop is too hot, it could destroy the bacterial sample, compromising the integrity of the culture.