Name _____________________________
DIY Yeast Experiment
Period _____ Date ________ Seat _____
Bakers use single-celled fungi called yeast to make bread dough rise before baking it. When
yeast feed on the sugars in bread dough, they produce alcohol and carbon dioxide gas (CO2) as
waste products. The carbon dioxide released by yeast is what causes the bread dough to rise.
Some of the alcohol yeast produce will evaporate during baking.
There are many variables that can affect how fast yeast, when consuming sugar, produces
carbon dioxide and alcohol. You will plan a procedure to test one variable.
Write an experimental question to be answered with a controlled experiment. Be sure the
question includes both a manipulated variable and a responding variable.
Choose your manipulated variable and responding variable from this list.
Type of yeast
Type of light
Amount of water
Amount of sugar consumed
Mass of yeast
Mass of sugar
Amount of alcohol produced
Temperature
Amount of light
Amount of carbon dioxide (CO2) produced
Source of sugar (table sugar, honey, orange juice, corn starch, etc.)
Question #1
Identify the manipulated variable and responding variable you chose in the space below. Write
your experimental question, including both variables.
Manipulated/independent variable:
Responding/dependent variable:
1
Name _____________________________
DIY Yeast Experiment
Period _____ Date ________ Seat _____
Experimental question:
Plan a controlled experiment to answer your experimental question. You may use any
materials and equipment in your procedure. A list of materials you may find useful is provided
in the boxes below.
Beakers
Flasks
Rubber stoppers
Graduated cylinders
Glass tubing
Plastic tubing
Ring stand and clamp
Buckets
Pans
Thermometer
Hot plate
Lamp
Stirring rods
Measuring spoons or scoops
Electronic balance
Source of sugar (table sugar, honey, orange
juice, corn starch, etc.)
Ways of Measuring
Metric Ruler
Gas collection apparatus (to collect milliliters of gas
using water displacement)
CO2 sensor (measures the amount of CO2 in parts
per million or ppm)
Sugar sensor (measures the percent of sugar in
solution)
Alcohol sensor (measures percent alcohol)
Be sure your procedure includes:
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logical steps to do the experiment
two controlled (kept the same) variables
one manipulated (independent) variable
one responding (dependent) variable
how often measurements should be taken and recorded
2
Name _____________________________
DIY Yeast Experiment
Period _____ Date ________ Seat _____
You may use words and/or labeled diagrams in your answer.
There is additional space to write your procedure on page 4
3
Name _____________________________
DIY Yeast Experiment
Period _____ Date ________ Seat _____
Additional space to write your procedure
Describe a step in your yeast procedure that ensures the results of the experiment will be
reliable.
Describe a step in your yeast procedure that ensures the results of the experiment will be valid.
4