Decomposition experiment.

We have been studying decomposition.  It is a fairly easy concept to grasp but this experiment helped by given a visual of what really happens when something is decomposing.

Supplies:
~two banana slices
~two plastic baggies
~yeast

Procedure: 
~put just a little water on each banana
~sprinkle only one banana slice with yeast-just enough to cover the top-not an excessive amount
~place both bananas in the baggies-one banana for each baggie
~close it up and then observe over a week

What is the point of this?  To find out what effect the yeast would have on the banana slices.

First day:
Banana without yeast-the banana was a little darker, mainly in the area of the seeds.
Banana with yeast-the banana turned browner.

Third day:
Banana without yeast-the banana was browner.
Banana with yeast-the banana was softer and had an odor.

Fifth and final day: 
Banana without yeast-not much difference.
Banana with yeast-the banana was a soft, blob of brown stink!

banana with yeast-fifth day.

banana with no yeast-fifth day.

So what did we learn from this?  I learned never to use a fruit that I love in a science experiment.  But really, the banana with the yeast decomposed more rapidly than the banana without the yeast.  This rapid decomposition was caused by the fermentation of the yeast.  The yeast used the starch from the banana to reproduce itself which caused decomposition which changed the color and consistency of the banana.  And there you have it!