To design and perform an experiment that will show the difference between microbial growth after washing and not washing your hands.

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Investigating Biological Spread

Aim: To design and perform an experiment that will show the difference between microbial growth after washing and not washing your hands.

Materials:

  • 8 Sterile Agar plates                        
  • Standard soap
  • Sterile paper towel
  • A growth medium

Method: Eight agar plates filled with a sterile growth medium had lines drawn down the middle of the lid and a ‘W’ and a ‘U’ were drawn at the top, standing for washed and unwashed. Seven students were then asked to press three fingers into the ‘W’ side of an agar plate. The students then washed their hands thoroughly with standard soap and dried their hands with sterile paper towels. The unwashed ‘U’ side of the agar plates then also had three fingers pressed into it the same way as before. All seven agar plates and one agar plate that hadn’t been touched were left in an incubator for a week at 35°C. The results found were then researched using the Internet to find out what the different microbes were.

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Results: The experiment has shown that even washing your hands doesn’t kill all microbes as seen in all agar plates except number two. This means that the experiment wasn’t conclusive however it did provide some useful information. Most of the microbes that survived the hand washing were large colonies of fungi. The control used to stop pathogens and/or contamination had to be strict while conducting the experiment and these measures were that the lids were only taken off for the shortest possible amount of time and no one was to breath on the plates. The agar plate that wasn’t ...

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