Weekly Report: Water-baths and Peas

During the week of Jan. 26 – Jan 30, we had the opportunity to complete our next lab, with seeds of mung, barley, and of course, the historic pea; our training ground. We were charged with designing an experiment that would discover the rate of respiration of the germinating seeds, with glass marbles as the control. Changing either temperature, pressure, or volume, we could calculate the rate of change, and in AP Biology, it is well known that an unchanging dependent variable is as common as Mr. Kite giving us pathogenic E.coli to do a lab on, i.e, not common at all.

The original experiment involved peas placed in 4 different vials; in order to act as control, glass beads were used. This experiment measured the effect of temperature on the rate of respiration. We used two water baths, one at room temperature and another at 10 C. 25 germinating peas were put in one vial, and to match, the same volume of non germinating peas and glass marbles were put in another vial; this was repeated for the other bucket too. Respirometers, which measure respiration stopped off each vial, then each was partially submerged in the water. We discovered that temperature did have a significant effect on respiration rate, and next, we were charged to design our own experiment. My partner and I decided to change the peas to barley and maintain temperature as our independent variable. One thing I noticed about using barley was that it tends to be longer than peas, and based on some of the literature I have read, there may be a correlation between seed size and germination, but that’s another question for another day. I also discovered the scientific use of petroleum jelly to safeguard the stopping reputation of respirometers, and though our hands were forcibly moisturized, the experiment ran smoothly. The barley proved the relationship between temperature and respiration, with slightly higher results than the peas.

Application has been on our lists this year as the crucial component of everything we do. In the case of my experiment, I recognized the ramifications of cellular respiration on the crops that we consume, especially grain, which is a type of grass. It is a fruitless endeavor to regulate Mother Nature, but proper planting practices based on biological principles can mean the difference between the bread basket of the United States, and the barren wasteland of the same.


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