Why should an inoculating tool be allowed to completely cool after heating before picking up bacteria?

• A. To prevent killing the bacteria with residual heat
• B. To avoid contaminating the tool with airborne microbes
• C. To ensure the tool does not melt during inoculation
• D. To increase the rate of bacterial growth on the medium

Answer: (A)

Verified step by step guidance

1. Understand the purpose of heating an inoculating tool: it is sterilized by passing it through a flame to kill any existing microbes.
2. Recognize that immediately after heating, the tool is extremely hot and can transfer this heat to the bacteria when picking them up.
3. Consider what happens if the tool is still hot when it touches the bacteria: the residual heat can kill or damage the bacteria, preventing successful transfer.
4. Realize that allowing the tool to cool ensures it is sterile but not hot enough to harm the bacteria, maintaining their viability for inoculation.
5. Conclude that the main reason for cooling the tool is to prevent killing the bacteria with residual heat, rather than concerns about contamination, melting, or growth rate.