Factors That Limit Yeast Growth Did you know that yeast is a living thing? It feeds, reproduces, and even excretes waste.

Factors that LIMIT Yeast Growth →Yeast lives in a moist sugar-rich environment. →In order to grow, it requires food in the form of a sugar.

The Control Experiment What are the ideal conditions that yeast can grow in? Where could we find this information?

Conduct the control experiment Materials: Yeast….how much? water…..how much? what temperature? sugar….how much? beaker timer thermometer data recording sheets

Factors that LIMIT Yeast Growth Limiting factors are things that prevent a population from growing any larger.  What are the limiting factors for yeast? Can it grow in any conditions? YOUR JOB: Design an experiment to answer your own question about the growth of yeast.

Question? Think carefully about what you want to find out in your experiment Write a Question you would like answered about factors that affect the growth of yeast. What do you want to know about yeast growth and limiting factors?

What is a Hypothesis? A guess? No.  A hypothesis is sometimes described as an educated guess.  That's not the same thing as a guess and not really a good description of a hypothesis either.  Let's try working through an example.

If you put an ice cube on a plate and place it on the table, what will happen? Most people would agree with the hypothesis that: An ice cube will melt in less than 30 minutes.

You could sit and watch the ice cube melt and think you've proved a hypothesis. 

But you will have missed some important steps. For a good science experiment you need to do quite a bit of research before any experimenting.  Start by finding some information about how and why water melts.  You could read a book, do a bit of Google searching, or even ask an expert. 

Now, using all your research, try to restate that hypothesis.   For our example, you could learn about how temperature and air pressure can change the state of water.  Don't forget that elevation above sea level changes air pressure too. Now, using all your research, try to restate that hypothesis. An ice cube will melt in less than 30 minutes in a room at sea level with a temperature of 20C.

Hypothesis Write a hypothesis based on your question. Your hypothesis should be a cause and effect statement that you can test. It should be a sentence in the form…. “If I change________then_______because…” Explain your reasoning why you think this result will occur.

Materials Make a point-form list of all the materials you will need to complete your experiment. Be sure to include exact sizes and quantities.

Procedure Your procedure should be a detailed and numbered step-by-step list of instructions for conducting your experiment. Make sure to include amounts, measures, and temperatures needed to accurately complete the experiment.

Data and Observations The growth and yeast should be recorded in a table every minute for a 20 minute interval (as done by your teacher in the control). Your final results for all tests must be represented in a graph format.

Analysis & Conclusion Answer the Analysis questions on pg. 21 in your text. Use the guide, “Writing Conclusions for Science Experiments” (handed out in class) to complete your conclusion write-up Be sure to hand in the self-assessment rubric for this experiment.

Wordpress.com 1. Create a new page called: YEAST LAB 2. Add the YEAST LAB to your science page in the form of a drop down menu 3. You will be adding titles to your YEAST LAB page and sharing your results using the Scientific Investigation Steps.

Wordpress Continued Ex. On your YEAST LAB blog page you would write: 1. PROBLEM/QUESTION Place your answer underneath 2. HYPOTHESIS State your hypothesis here Etc. until you have shared your conclusion