Exploring Yeast Activity
Safety Rules Reminders:
1. Glassware is being utilized today, gently place test tubes and beakers against lab tables.
2. If glassware is chipped or broken, notify teacher immediately.
3. Hot plates will be used, to prevent injury, do not touch top of hot plate with bare hand. Use caution when removing beaker or test tubes from hot plate.
Materials: [per one group]
3 stirrers ¼ teaspoon 250 ml beaker
test tube rack stopwatch 400 ml beaker
3 test tubes pipette
tape hot plate
sharpie marker
Procedure:
1. Place a piece of tape around top of test tube. Using a marker, write the name of the substance to be tested on the tape. Every group will have test tube containing water and at least two other substances.
Record substance tested in the substances tested section of the lab report.
2. Use a pipette to measure 7 ml of water and add it to the test tube
labeled water. Return test tube to test tube rack.
3. Use a pipette located at each station to measure 7 ml of the substance you are testing, and add each to the appropriate labeled test tube. Return test tubes to test tube rack.
4. Add ¼ teaspoon of yeast into each of the test tubes containing substances to be tested. Using a different stirrer for each substance, gently mix each solution for one minute. Use the stopwatch to be accurate with your time.
5. Place all test tubes in a beaker of warm water located on hot plate. Start stop watch, allow test tube to remain in warm water for 12 minutes.
6. Remove test tube from water. Measure the height of foam produced.
[Measure from top of solution to top of foam column]. Record measurement [in millimeters] in data table. Place test tube in test tube rack.
7. Drain all mixtures in sink. Clean all stirrers return to empty test tube. Clean test tubes using a test tube brush located at the sink. Place test tubes upside down in empty beaker.