if you give yeast sugar and warm water it will start reproducing. If you put higher voltage though it it will act as a semi-conductor. It is really awesome.

http://www.wprld-of-a-new.comuf.com

Ehm, cells and most organic molecules tend to have semi-conductive properties. As the link does not lead anywhere I am not sure where the awesomeness is...

I fail to visualize this.

 

A bucket of water, sugar and yeast. Two electrodes. High voltage?

 

Water actually conducts, so where is the semiconductor?

Usually only across small gaps. E.g. put a cell on top of an electrode, and then put another electrode on top of the cell. Measure current through the cell. The I/V curve is roughly that of a bad semiconductor. Or you could grow cells between electrodes. Depending on cell type it does not work for larger distances.