Yeast Lab

Learning Targets

Students will construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
Students will develop a model to describe how food is rearranged through chemical reactions forming new molecules that support growth and/or release energy as this matter moves through an organism.

Success Criteria

I have compared the processes of Photosynthesis and Cellular Respiration.
I have made a prediction about the outcome of the lab based on evidence from past reasoning and observation.
I have developed a model of how photosynthesis and cellular respiration cycle matter through organisms.

Background

Photosynthesis is the process by which plants and other things make food. It is a chemical process that uses sunlight to turn carbon dioxide into sugars that the cell can use as energy. As well as plants, many kinds of algae, protists and bacteria use it to get food. Photosynthesis is very important for all life on Earth. Most plants either directly or indirectly depend on it.

Cellular respiration is the process of breaking sugar into a form that the cell can use as energy. This happens in all forms of life. Cellular respiration takes in food and uses it to create ATP (Adenosine Tri-Phosphate) a chemical which the cell uses for energy. Usually, this process uses oxygen, and is called aerobic respiration. It has four stages known as glycolysis, Link reaction, the Krebs cycle, and the electron transport chain. This produces ATP which supplies the energy that cells need to do work.

Yeast is a living fungus. We can find yeast in all things bread. Yeast is used to make bread rise but only if the right ingredients are introduced.

Driving Question

Team Talk - agree/disagree

Does Fungi Photosynthesize or does it go through Cellular Respiration to obtain energy?
What is your evidence?

Lab Time!

Materials

3 test tubes and test tube holder
3 balloons
3 grams yeast
1 gram sugar
1 gram salt
30 ml warm water
scale
containers for measuring

Procedure:

Label test tubes with G- for sugar, S – for salt, T- for tap water
Put 1 gram of yeast in each test tube
Pour 10 ml of warm water into each test tube
swirl each vial for 1 minute
Measure 1 gram of sugar and 1 gram of salt
Prepare 3 balloons by pushing all air out of each and checking for holes
At the same time place sugar in “G” test tube and salt in “S” test tube (nothing except water in T test tube
Place balloons over tops of test tubes
Swirl test tubes Gently
Set test tubes in holder
Start Timer
With your team, answer the Pre-Observation Questions below.
Make observations at 5 minute intervals
- draw diagrams, take measurements, etc
After 45 minutes, make Post-Observations and clean up all materials

Pre-observation

What results do you expect for each vial? Explain your reasoning.
How will you know if yeast (fungi) undergoes photosynthesis or cellular respiration?
Why do we have a vial with just water and yeast in it?

Post-observation

Which solution's balloon was the most filled? Why?
Which solution's balloon didn’t fill? Why?
Formulate a conclusion. Was Cellular respiration occurring or Photosynthesis?
How are fungi cells similar to Plant Cells?
How are fungi cell different from Plant Cells?

MS-LS1-7. Develop a model to describe how food is rearranged through chemical reactions forming new molecules that support growth and/or release energy as this matter moves through an organism

From Molecules to Organisms