Measure cellular respiration in living and dormant pea seeds at two different temperatures.

Authors Avatar

Joseph Kundukulam

10/14/03

Period: 2nd

Lab Five: Cell Respiration

Introduction:

        This experiment will measure cellular respiration in living and dormant pea seeds at two different temperatures. Cellular respiration is the release of energy by metabolic chemical oxidation. Respiration’s reactants are glucose and oxygen. The reaction’s products are water, carbon dioxide, and 686 kilocalories of energy per glucose molecule. Respiration occurs less in seeds that are dormant. Such seeds are living but require negligible amounts of energy. In contrast, germinating seeds are active and require greater amounts of energy.

        The instrument used in this experiment for the calculation of oxygen consumption is the respirometer. A respirometer adheres to the basic concepts of the gas law. The main concept that is followed is that the volume of gas is directly proportional to the number of molecules of gas. Because carbon dioxide is removed by the potassium hydroxide, the change in volume of the gas is directly proportional to the amount of oxygen consumed by the peas. It is also important to remember that gases diffuse from regions of high concentration to areas of lower concentration. As carbon dioxide is converted into a solid, the net pressure of the gas and the volume decreases.

        Metabolic processes are important in the production of ATP. Metabolism regulates cellular activities. The pathways regulate the catabolic breakdown of glucose molecules. By harnessing the energy in the glucose molecule in small pieces, the cell conserves and prevents the loss of this energy. Each step in cellular respiration insures that the energy in the glucose bonds is conserved.

        The amount of cellular respiration reflects the amount of activity in the cell. In order to produce energy and continue living, cells perform cellular respiration. Thus, cells that perform cellular respiration more are also more active. There are three ways that the amount of cellular respiration can be measured: the consumption of oxygen, the production of carbon dioxide, and the release of energy.

Hypothesis:

        If a respirometer only contains germinating peas and is placed in a temperature of twenty five degrees Celsius, then this respirometer will show the highest amount of oxygen consumption.

Materials and Method:

        The materials used were dry (non-germinating) peas, germinating pea seeds, six respirometers, water, two water bins, graduated cylinder, cotton, and fifteen percent potassium hydroxide. First, a graduated cylinder was obtained and filled with fifty milliliters of water. Fifteen germinating peas were dropped in the cylinder. The displacement was recorded and the peas were left on a paper towel to dry. Second, fifteen dry pea seeds were added into the graduated cylinder. Glass beads were added until the displacement volume was the same as in Step 1. Third, glass beads were added into the graduated cylinder until the displacement volume was the same as in Step 1. The first three steps were repeated to prepare a second set of germinating peas, dry peas, and beads for use in respirometers four, five, and six, respectively. A piece of cotton soaked with KOH was placed in the bottom of each of the six respirometers and nonabsorbent cotton was placed on top of the soaked cotton. The first three respirometers were placed in a water bin at room temperature. The last three respirometers were placed in a water bin with water at ten degrees Celsius. After an equilibration of three minutes, the respirometers were immersed in the water baths. The position of water in the pipette was checked every five minutes for a period of twenty minutes.

Join now!

Variables:

The independent variables being tested are temperature and germinating versus dry pea seeds. The dependent variable is the amount of oxygen consumed. The control is the respirometer that contains only glass beads.


Data and Observations

Pea Volume: 55 mL

     Corrected Difference in the amount of Oxygen Consumed (mL)

Observations: It was noted that germinating peas showed the greatest change in water volume at twenty five degrees Celsius. At ten degrees Celsius, the change in water volume was less. In contrast, dry peas showed very little change at both temperatures.


This is a preview of the whole essay