Team+2

A Team 2: Sophia, Rebecca, Victoria, Brianna

Hi team! So since this is due Friday it would be ideal to split up the work and then pull it together on here tomorrow night. We can talk about splitting the work tomorrow in class so theres no confusion! :) from Becky!

I wasn't sure how we split this up or if you guys were posting in here for the lab so I just did a couple of things and will continue doing them.Edit,remove, fix everything because I wasn't sure on hypothesis.-Brianna

I'm not sure exactly what to do but I suppose I have to finish it -Sophia

Lab report is done! im printing it out just in case ~ Becky

**AP Biology Laboratory 12:** **Dissolved Oxygen and Aquatic Primary Productivity Lab** To measure dissolved oxygen in a water sample using the Winkler Method, measure primary productivity, and investigate some factors that can affect the primary productivity of a system. If the temperature of the sample is cooler, then the saturation percent will be higher. Refer to lab handout (reference; “Dissolved Oxygen and Aquatic Primary Productivity” lab, received from Mrs. McLoughlin, April 27, 2012). __Temperature and Dissolved Oxygen__ The titration readings for sodium thiosulfate for each sample were as follows: 10° Celsius was 1.06 mL, 20° Celsius was 0.84 mL, and 30° Celsius was 0.67 mL. These readings were then used to calculate the DO. Each 0.1 mL of sodium thiosulfate used in the titration equals 1 ppm DO, or 1 mg DO per L of water. The data collected is seen about in the graph labeled “Temperature and Dissolved Oxygen”. After the titration of sodium thiosulfate, the percent saturation was found by the use of Figure 1: Nomograph of Oxygen Saturation (the graph is interpreted by the use of a ruler matching up the water temperature as found by the thermometer and the oxygen (mg per liter) as found by the titration (DO). The saturation in turn was then the amount that the ruler passed through). The results showed that the saturation of 25° Celsius was that highest at 98%. The 10° Celsius sample was second with 95%, and 30° Celsius was third with 90%. There may be errors in this lab due to human error in titration accuracy and because the temperatures were not kept constant during the length of the experiment. Since the amount of dissolved oxygen was highest at 20° Celsius, the results do not support the hypothesis. Even though the data is inconclusive, it does indicate that temperature has an effect on the saturation of dissolved oxygen.
 * Activity A: //The Effect of Temperature on Dissolved Oxygen//**
 * Purpose****:**
 * Hypothesis:**
 * Materials:**
 * 3 BOD bottles
 * Maganous sulfate
 * Starch indicator
 * Sulfamic acid and measuring spoon
 * Alkaline potassium iodide azide
 * Sodium thiosulfate
 * 2 titration syringes
 * 2 20-mL sampling vials
 * Waterproof marker
 * Thermometer
 * 60-mL syringe with tubing attached
 * Methods/ Procedure:**
 * D****ata and Observations:**
 * Temperature................ (Degrees Celsius) || GroupDO................. || Group%Saturation.......... ||
 * 10 || 10.6 || 95% ||
 * 25 || 8.4 || 98% ||
 * 30 || 6.7 || 90% ||
 * Analysis: **
 * Conclusion: **

To measure dissolved oxygen in a water sample using the Winkler Method, Measure primary productivity, and investigate some factors that can affect the primary productivity of a system. If gases dissolve to a greater extend in liquids at cooler temperatures, then there will be a greater amount of dissolved oxygen in the bottles that have light blocking screens. Refer to lab handout (reference; “Dissolved Oxygen and Aquatic Primary Productivity” lab, received from Mrs. McLoughlin, April 27, 2012). __Group Productivity Data__ There are high levels of dissolved oxygen in the samples which were exposed to large amounts of light. However after 3 screens the amount of dissolved oxygen drops to zero. This makes it so the data shows no conclusive pattern or rate of decline. This could be due to several factors including human error, proximity of the lamp to the different samples, or also if the lamp affected the temperature of the samples. The protists could have been undergoing respiration and producing oxygen when exposed to large amounts of light, but stopped producing oxygen because of the requirement of light for respiration. Since the algae stopped producing oxygen in increased darkness, it can be concluded that there is less oxygen in samples with less light. However the rate cannot be concluded due to inconclusive results.
 * Activity B: //The Effect of Light Intensity on Oxygen Production by Chlorella//**
 * Purpose:**
 * Hypothesis:**
 * Materials:**
 * 7 BOD bottles
 * Chlorella culture
 * Manganous sulfate
 * Starch indicator
 * Sulfamic acid
 * Alkaline potassium iodide azide
 * Sodium thiosulfate
 * Titration syringe
 * Sampling vials
 * 17 fiberglass screens
 * Aluminum foil
 * Measuring spoon
 * Methods/ Procedure: **
 * Data and Observations:**
 * Bottle.......... || DO............. || NetProductivity.......... || GrossProductivity....... ||
 * Baseline || 9.9 || - || - ||
 * Dark || 1 || - || - ||
 * Light (0) || 13 || 3.1 || 12 ||
 * 1 Screen || 15.1 || 5.2 || 14.1 ||
 * 3 Screens || 0 || -9.9 || -1 ||
 * 5 Screens || 0 || -9.9 || -1 ||
 * 8 Screens || 0 || -9.9 || -1 ||
 * Analysis:**
 * Conclusion:**