AP Biology Lab Reports

Cell Respiration Lab Report

Data and results:

Introduction:
Cellular Respiration is a series of biological processes in cells that converts energy from nutrients( uses oxygen and water) into adenosine triphosphate; also creates carbon dioxide as a waste product. The processes are Catabolic reactions. Cellular respiration is the key way that cells get energy to perform basic activities. Cellular Respiration is mainly seen as a exothermic redox reaction. The most commonly used nutrients are amino acids, sugars, and fatty acids. Cellular Respiration is a form of an aerobic reaction because it uses both oxygen and pyruvate. The four stages of cellular respiration are glycolysis, pyruvate oxidation, Krebs cycle, and then oxidative phosphorylation. Glycolysis takes place in the cytoplasm and takes glucose and converts it to two molecules of pyruvate and a three carbon organic molecule, in these reactions the ATP is made. Pyruvate oxidation takes place in the mitochondrial matrix this is when pyruvate molecules are bound to acetyl CoA to be converted into a two carbon molecule and carbon dioxide is released in this step. In the Krebs cycle there are eight steps that starts with the acetyl CoA reacting with oxaloacetate to form citrate ( https://www.britannica.com/science/ tricarboxylic-acid-cycle ) . The Krebs cycle produces ATP, NADH, and FADH. Finally in oxidative phosphorylation the NADH and FADH drop their electrons off at the electron transport chain, whereas the electrons move down energy is released and used to kick protons out of the matrix creating an imbalance. Then ATP synthase brings the protons back resulting in the formation of ATPs ( https://courses.lumenlearning.com/boundless-biology/chapter/oxidative -phosphorylation/ ). When the cell doesn't have oxygen available the cell instead goes through fermentation resulting in the temporary buildup of lactic acid in an organism's body.
    In the Cellular respiration lab two different temperature (24 and 10 degrees Celsius) water baths were set up with three respirometers in each. One respirometer in each bath had 25 germinating peas, one had 25 dry peas with some glass beads, and one had just glass beads. A drop of red food coloring was added to the tip of the respirometer to visualize the decrease volume of the gases resulting in the drop moving up the tube. The water moved the drop of food coloring up the tube because potassium hydroxide was added to solidify the carbon dioxide, and the peas were using the oxygen for cellular respiration, meaning there was less gas in the way. Two predictions were that if the peas are kept at 10 degrees Celsius then they will respire at a slower rate than the peas at room temperature, and if the peas are germinating then they will respire at a faster rate than dry peas and glass beads.

Materials and Methods: Refer to laboratory handouts

Conclusion:
         The experiments conducted to support the hypotheses were accurate. It was proven that if the peas are kept at 10 degrees Celsius then they will respire at a slower rate than the peas at room temperature because the oxygen consumption was .265 ml vs. .59 ml. The hypothesis that if the peas are germinating then they will respire at a faster rate than dry peas and glass beads because the germinating peas consumed (room Temp.) .59 ml while the dry peas consumed .18 ml, and the beads .11 ml. No experiments are ever perfect because there is always a little human error. Also, the  water baths may not have been exactly the right temperature, could have counted the wrong number of peas, and there could have been small leaks in the respirometers. The reading of the puppets could have been wrong and math calculations incorrect. To minimize errors and missteps more than one person could do each step so lab partners are double checking each other's work.