Yeast Fermentation
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Overview/Introduction: Yeast is fungi that produce carbon dioxide when sugar is available. This chemical reaction can be used to introduce metabolism, chemical balancing, and limiting resources. This activity is adapted from Biology Today. It is modified to include discrete steps of the learning cycle, cooperative learning strategies, and introduce students to computer-linked probes. Purpose or Objective: Students will measure the temperature change involved in the production of carbon dioxide by yeast. Students will indentify products and reactants in a chemical and balance the equation. Time Required: Three 50 minute class periods Materials, Tools, and Resources Needed: PC with a free 9 pin serial port Science workshop 500 interface Temperature sensor Yeast solution Sugar solution Flask apparatus (see diagram) Lime water Tubing Teacher Preparation:
Teacher should prepare a solution of yeast the night before the activity. Teacher should be familiar with the learning cycle and inquiry-based instruction. Prerequisite Student Knowledge: This activity is designed for high school students struggling with science.Therefore,the prior knowledge is limited to the ability to cooperate in a group. The level of subject content can be quickly elevated after the students are engaged in the activity. Procedure: Activation: Students are asked if they've heard about the shark bites off the coasts of Florida. Does a shark normally east human flesh? What types of foods do you eat? Does your body make your own food or do you have to eat? In other words, could you not eat and survive? In this exercise we are going to learn what happens when a different type of organisms eats? Specifically we are going to study yeast? Take a few minutes and record what you know about yeast. What does yeast eat? What type of organism is yeast? Why we use yeast to study foods? Note: Answers to these questions develop the baseline used to measure the student's progress throughout this activity. Tangent questions (if students are not familiar with yeast): What does yeast look like? Procedure:
Actualization: Students will manipulate their data through Data Studio. A graph is generated during the activity. This graph can be exported as a bmp file and inserted as a graphic file in MS-Word. The data can be exported as a text file or copied to an Excel Spreadsheet. MS Word will be used to complete the lab write up. An alternative is for students to complete a Power Point presentation which contains all of the elements of a good lab write-up. Prepare a graph of the temperatures observed over the last two days. Analysis questions: What does the curve of the graph represent? What would happen if you changed the amount of yeast or the amount of sucrose? What is the chemical reaction taking place in the bottle? How does yeast release energy from sucrose? How would you design and experiment to demonstrate that fermentation is really taking place? Vocabulary to be introduced: Metabolism, Sucrose, Lime water, Fermentation Application: What types fo foods do human eat? What is in this food? Design and experiment that determines the amount of energy available in a snicker bar, peanut butter, potato, egg and any other foods that are interest to you. Review this with your teacher and then do the experiment. Be prepared to share your results with your classmates. Student Handouts/ Record Sheets: A story about Yeast- This is a reading exercise to expose students to more information about Yeast. DataStudio introduction - a mini-howto guide The yeast-sugar apparatus setup-a diagram of the setup Analysis Questions
Student Discussion Questions: How much sugar is left after two day? How do you measure this amount?
Assessment: Students are evaluated formatively as the teacher is monitoring the groups. The rubric below is helpful as a summative assessment. A sumative written exam may be used after more students have accomplished more activities on metabolism. The groups decision on designing the tests of food consumed by humans will help the teacher determine if growth has occured beyond the baseline.
Rubric:
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Grade: 10,11 Subject: ICS-2 California Content Standards Addressed: Chemical Bonds: Biological, chemical, and physical properties of matter result from the ability of atoms to form bonds from electrostactic forces between electrons and protons and between atoms and molecules. Conservation of Matter and Stoicchiometry: The conservation of atoms in chemical reactions leads to the principle of conservation of matter and the ability to calculate the mass of products and reactants. Investigation and Experimentation: Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content int he other four strands, students should develop their own questions and perfom investigations. Students will: a. Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data analyze relationships, and display data.
National Education Technology Standards for Students Addressed:
Students use technolgy to locate, evaluate, and collect information from a variety of sources. Students use technology tools to process data and report results.
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