Yeast Lab Interview This begins the second of three days of lab investigation.
Yeast Populations Student Materials Yeast is a single-cell fungus that produces carbon dioxide as a byproduct of cellular respiration. The release of carbon dioxide causes bread dough to rise. Because the yeasts are small and reproduce rapidly, yeast organisms are useful for studying various factors such as food availability, temperature change and a shift in pH that may influence the rate at which a population grows.
These cells produce carbon dioxide gas as a waste product and the amount of carbon dioxide produced directly relates to the number of living yeast organisms.
Your Task You and your lab partner will grow yeast in a molasses solution food for the yeast and investigate how one factor influences the change in yeast population growth as measured by the amount of carbon dioxide produced. In your words, state the problem you are going to investigate.
Include a clear identification of the independent and dependent variables that will be studied. Design an experiment to solve the problem. Your experimental design should match the statement of the problem and should be clearly described so that someone else could easily replicate your experiment.
Include a control if appropriate and state which variables need to be held constant. General Procedure for growing yeast populations: Place your palm over the end of the small test tube and invert it five times. Quickly invert the tubes so the mouth of the large tube is up.
Place in the test tube rack. Subtract the initial gas bubble size from the total bubble size. Remember you will need this data to calculate the total volume of carbon dioxide each day over five days.
Review your design with your teacher before you begin your experiment. While conducting your experiment, take notes and organize your data into tables. Students must wear approved safety goggles and follow all safety instructions.
When you have finished, your teacher will give you instructions for cleanup procedures, including proper disposal of all materials. Communicating Your Findings Working on your own, summarize your investigation in a laboratory report that includes the following: A statement of the problem you investigated.LESSON 2: Population Explosion (Yeast Lab) (Day #2 of 3) LESSON 3: Population Explosion (Yeast Lab) (Day #3 of 3) LESSON 4: Population Dynamics (Day #1 of 3).
Each student turned in a lab write-up in traditional form (introduction, methods, results, and discussion and conclusion).
Specific components were included in the report. Lab 9. Population Growth: What Factors Limit the Size of a Population population dynamics.
investigate how different factors in Setting up a population of yeast: 1. Use a graduated pipette to transfer 1 ml of the yeast from the class culture to a standard test tube. This lesson is the second of two that explore cellular respiration and population growth in yeasts.
In the first lesson, students set up a simple way to indirectly observe and quantify the amount of respiration occurring in yeast-molasses cultures.
Yeast Population Dynamics. At the conclusion of the experiment you should allow about 30 minutes for the students to write about their results or you may prefer to have the students complete the lab report for homework. A yeast suspension needs to be prepared one hour before the lab.
(1 gram of yeast per ml of water). Objectives. 1. To set up a student designed experiment on the factors affecting population dynamics in a species of flour beetles, Tribolium confusum. 2. To learn how to use the computer program Excel for graph construction and the computer program JMP for statistical tests.