Wednesday, October 5, 2011

Bacteria Lab- Part 2

Students found that EVERY location they tested had bacteria present!  Also, after quantifying bacterial growth we had very convincing evidence that the bacteria sampled grew much faster at 37C, (the same temperature as the human body), than at 4C (an average refrigerator temperature).   We used clear grids placed over the petri plates, and counted how many squares had bacterial growth present in them. Students calculated the average percent of squares with bacterial growth from the two temperature treatments, and made a bar graph to visualize their data.  We then discussed how to interpret our results.  Do bacteria always grow faster at warmer temperatures?  Is there an upper temperature limit where bacteria can survive?  Based off of our results, can we conclude bacteria are absolutely everywhere?  Or is it safer to conclude that bacteria are likely to be found in most places around our school?  We also took some video from class this week, so hopefully we can share that soon!

You might wonder how this is at all relevant to my turtle research. Abiotic conditions (such as temperature, moisture, etc) are important for all organisms.  One major concern with turtles is that climate change will influence population growth by altering the population sex ratio, because the gender of developing turtle eggs is determined by the temperature.  To this end, population growth of both turtles and bacteria may be directly influenced by temperature, although our ability to see this effect in turtles takes much longer. 

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