You will be handling rotting materials and rubbing alcohol, so protect yourself by wearing gloves and goggles.
Understanding what protects you from disease is very important when considering preventative health strategies. One of the first lines of defense from infection is the skin. A pathogen is an agent that can cause disease, such as a bacteria, virus, or microorganism. If pathogens cannot get through the skin, they cannot cause disease in the underlying tissue.
In this activity, you will investigate the importance of the skin as a barrier against disease.
Question
How does skin act as a barrier to pathogens?
Materials and Equipment
4 re-sealable plastic bags
4 fresh apples
1 rotting apple
cotton swabs
felt marking pen
paper towels
toothpick
rubbing alcohol
Dry Lab
A "dry lab" activity includes collected data and/or a video solution for your convenience. You can simply watch the following video and use the provided data, or if you wish to perform this lab for yourself, follow the procedure steps 1 through 8 described in the video. The same steps are included in written form in the documents available for download on the bottom of this page.
Analyzing and Interpreting
A student performing the procedure steps 1 through 8 recorded the following observations and results. What do these results indicate about how the apples were treated and the importance of the skin as a barrier to pathogens? Explain your answers.
Days
Apple 1 (no contact with decay)
Apple 2 (contact with decay, unbroken skin)
Apple 3 (contact with decay, scratched, untreated)
Apple 4 (contact with decay, scratched, treated with alcohol)
1
No change
No change
Cut is dark
Cut is dark
2
No change
No change
Cut is dark
Cut is dark
3
No change
No change
Cut is darker, looks softer and yellow around scratch
Cut is dark
4
No change
No change
Cut is darker, looks softer and yellow around scratch
Cut is dark
5
No change
No change
Cut is darker, looks softer and yellow around scratch
Cut is dark
6
No change
No change
Cut continues to get wider and softer looking, more yellowed
Cut is dark
7
No change
No change
Cut continues to get wider and softer looking, more yellowed
Cut is a bit darker and edges slightly softer
If apples show signs of decay in this experiment, what do you think is happening to the cells in the area of the decay?
Forming Conclusions
How important is the skin as a barrier to pathogens?
Do you think skin can stop all pathogens? Explain your answer.
Based on the results of this experiment, what prevention measures would you suggest for a school to have in place that would promote better health in instances where students may have accidentally cut themselves? Explain your answer.