second experiment

Overview of Cellular Respiration in Yeast

  • Cellular respiration is the process through which yeast convert sugar into energy in the form of ATP.

  • The byproducts of this process are carbon dioxide (CO2) and water (H2O).

Measuring Cellular Respiration

  • Carbon dioxide produced during fermentation can be measured as an indicator of respiration activity.

  • In this experiment, the number of CO2 bubbles produced will be counted as a measure of the rate of respiration.

  • Key steps include:

    • Mixing sugar with yeast to initiate the reaction.

    • Observing and measuring the CO2 bubbles formed over time.

Experimental Setup

  • Measuring CO2 Production:

    • Two test tubes will be prepared to compare the rate of reactions based on bubble formation.

    • Use a ruler to measure the length of the CO2 bubbles produced.

    • Mark the starting fluid level in the test tube with a marker for reference.

  • Inoculating with Yeast and Sugar:

    • Add a double dropper full of yeast to each test tube containing sugar.

    • Different temperatures will be tested: 0°C (ice bath), 21°C (room temperature), and 37°C (body temperature).

Temperature Considerations

  • Zero Degrees Celsius:

    • Yeast will be inactive, likely resulting in fewer CO2 bubbles.

  • Twenty-One Degrees Celsius:

    • Yeast is expected to be moderately active; bubbling should occur at a moderate rate.

  • Thirty-Seven Degrees Celsius:

    • Optimal temperature for yeast; enhanced activity leading to the greatest production of CO2 bubbles expected.

Experimental Procedure

  • Step-by-Step Instructions:

    1. Prepare three test tubes, one for each temperature, and ensure they are labeled.

    2. Mark the initial level of fluid in the test tubes with a marker.

    3. Create a vacuum by using a larger test tube to cover the yeast and sugar mixture, trapping any formed gas.

    4. Carefully turn the test tube to maintain the vacuum seal when observing bubbles forming.

    5. After the incubation period, measure the length of the CO2 bubbles produced for each test tube.

Clean-up and Final Steps

  • After the experiment, remove any markings on the test tubes with a special eraser to avoid leaving residue.

  • Ensure that all used materials are cleaned appropriately and disposed of safely.

  • The test tubes should be positioned to dry with their openings facing down to prevent any blockage.