Effects of Calcium Chloride Concentration on Chlamydomonas Reinhardtii Algae Growth

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Results

Figure 1: [pic 1]

Manipulation of calcium chloride in the tap media for the control group, experimental group two, and experimental group three, showed little advantage in increasing the calcium chloride concentration from two grams to four grams per two hundred milliliters. Control group, experimental group two, and experimental group three, showed a significant increase in growth between day one and day ten. However, experimental group one, with a decreased concentration of calcium chloride of one gram per two hundred milliliters, showed stunted growth compared with the other groups as shown in figure 1.

Discussion

The hypothesis stated, Chlamydomonas reinhardtii growth is related to calcium chloride concentration. The prediction that C. reinhardtii’s growth will increase with the addition of calcium chloride relative to the control group was incorrect. Experimental group one, with half the concentration of calcium chloride as the control group, showed noticeably stunted growth. While experimental groups two and three, with increased concentrations of calcium chloride, showed similar growth rate slightly below the control group’s growth rate. A study was conducted about calcium's role in C. reinhardtii mating reactions and it was found that with enlarged cAMP levels there was an increase in calcium two plus in the mating medium (“The Role of Calcium…”, 1993). In this experiment, algae growth rate peaked with the control group, which consisted of two grams of calcium chloride per two hundred milliliters of solution. We concluded that C. reinhardtii needs a baseline of about two grams of calcium per two hundred milliliters of solution to grow effectively.

Our results could have been caused by errors made during the experiment. Some errors that may have influenced the results of the experiment are the amount of constant light, the cleanliness of the cuvettes, and the calibration of spectrometer. An error with the amount of light could have been caused by the flasks being tightly packed with the rest of the class’s experimental flasks, which may have casted shadows. If shadows were casted, experimental data could have been altered. To try and prevent this there was a rotation of the flasks, deployed Monday through Friday, to help prevent unequal light exposure. But the flasks that were rotated Friday, were not rotated again until Monday. This may have caused an error in our data. Another possible error would be that some or all of the cuvettes were not properly cleaned. Also if any of the cuvettes used had smudges or other debris on the outside, it would have caused unreliable readings. The calibration of the spectrometer was also very important in accurate readings of our algae. If the spectrometer was not calibrated correctly before each reading, errors would have occurred in our data.

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