Name: __________________________________
Date: __________
Period: _________
Yeast in Action Lab
Unit 1: Cellular Organization, Biology
Background (from ​CK12.org​​):
Why do you need food? - ​The main reason you need to eat is to get energy.
Food is your body's only supply of energy. However, this energy must be
converted from the apple (or any other food you eat) into an energy source
that your body can use. The process of getting energy from your food is
called cellular respiration, and most of this process happens in the
mitochondria.
What is Cellular Respiration? - ​How does the food you eat provide energy?
When you need a quick boost of energy, you might reach for an apple or a
candy bar. But cells do not "eat" apples or candy bars; these foods need to be
broken down so that cells can use them. Through the process of cellular
respiration, the energy in food is changed into energy that can be used by the
body's cells. Initially, the sugars in the food you eat are digested into the
simple sugar glucose, a monosaccharide. Recall that glucose is the sugar produced by the plant during
photosynthesis. The glucose, or the polysaccharide made from many glucose molecules, such as starch, is then
passed to the organism that eats the plant. This organism could be you, or it could be the organism that you eat.
Either way, it is the glucose molecules that holds the energy.
ATP - S
​ pecifically, during cellular respiration, the energy
stored in glucose is transferred to ATP (Figure at right). ATP,
or adenosine triphosphate, is chemical energy the cell can
use. It is the molecule that provides energy for your cells to
perform work, such as moving your muscles as you walk
down the street. But cellular respiration is slightly more
complicated than just converting the energy from glucose
into ATP. Cellular respiration can be described as the reverse
or opposite of photosynthesis. During cellular respiration,
glucose, in the presence of oxygen, is converted into carbon
dioxide and water. Recall that carbon dioxide and water are
the starting products of photosynthesis. What are the products
of photosynthesis?
The process can be summarized as: ​glucose + oxygen → carbon dioxide + water​​. During this process, the
energy stored in glucose is transferred to ATP.
Energy is stored in the bonds between the phosphate groups (PO​4​-) of the ATP molecule. When ATP is broken
down into ADP (adenosine diphosphate) and inorganic phosphate, energy is released. When ADP and inorganic
phosphate are joined to form ATP, energy is stored. During cellular respiration, about 36 to 38 ATP molecules are
produced for every glucose molecule.
Cellular respiration involves many biochemical reactions. However, the overall process can be summed up in a
single chemical equation:
C​​6​H​
+ energy (stored in ATP)
​ ​12​O​
​ ​6​​ + 6O​​2​​ → 6CO​​2​​ + 6H​​2​O
​
Background Questions:
● What is the function of cellular respiration?
●
Do plant cells respire? If so, why?
●
What kinds of molecules are used for cellular respiration? Give specific examples.
●
What is ATP?
●
What is the use of ATP? Give three examples of how ATP is used in the cell.
●
How much usable energy is extracted from one glucose molecule?
Lab Introduction:
In this laboratory activity, you will be investigating the production of gas by yeast. As you may know, yeast are
unicellular fungi that are often used in the production of foods, such as bread and alcoholic beverages. Certain
strains of yeast can also cause skin infections in humans. We will conduct two experiments to determine how the
concentration of sugar in a solution and temperature affects the rate of cellular respiration in yeast.
Materials:
▪ Yeast suspension
▪ Sucrose solutions of various concentrations
▪ Graduated cylinders
▪ Electronic scale
▪ Timer
▪
▪
▪
▪
Safety goggles
Water at various temperatures
Test tubes
Ruler
Sugar Concentration Procedures & Data
Temperature Procedures & Data
Hypothesis
As the concentration of sugar ____________, then the
Hypothesis
As the temperature ____________, then the rate of
rate of cellular respiration will ____________,
cellular respiration will ____________,
because_____________________________________.
because_____________________________________.
Therefore, I will observe _______________________. Therefore, I will observe _______________________.
Experimental Design:
Experimental Design:
Independent Variable: _________________________
Independent Variable: _________________________
Dependent Variable:
Dependent Variable:
___________________________
___________________________
Controls (List three): __________________________
Controls (List three): __________________________
___________________________________________
___________________________________________
Procedure:
1. Label four test tubes 1-4.
2. Add 5 ml of yeast suspension to each tube.
3. Make sugar solutions:
▪ Do not add any sugar to Tube 1 (0% sugar).
▪ Add 0.25 g of sugar to Tube 2 (5% sugar).
▪ Add 0.5 g of sugar to Tube 3 (10% sugar).
▪ Add 1.0 g of sugar to Tube 4 (20% sugar).
4. Cover the tube with your thumb and mix each
solution until the yeast is dissolved.
5. When the sugar is dissolved, start timing the
reaction. Record the time in the data table below
in the “Time Start” column.
6. At 15 minutes, measure the amount of bubbles at
the top of the tube in centimeters and record it on
the data table below. Record the height of bubbles
in the data table below in the “Height of Gas
Bubble” column.
Procedure:
1. Label four test tubes 1-4.
2. Add 5 ml of yeast suspension to each tube.
3. Add 0.5 g of sugar to each tube (10% sugar).
4. Cover the tube with your thumb and mix each
solution until the yeast is dissolved.
5. When the sugar is dissolved, start timing the
reaction. Record the time in the data table below
in the “Time Start” column.
6. Immediately place each tube in the water bath for
the correct temperature.
▪ Tube 1: ice bath (0°C)
▪ Tube 2: room temperature (25°C)
▪ Tube 3: warm water (40°C)
▪ Tube 4: boiling water (100°C)
7. At 15 minutes, measure the amount of bubbles at
the top of the tube in centimeters and record it on
the data table below. Record the height of bubbles
in the data table below in the “Height of Gas
Bubble” column.
Individual Data Table:
Independent Variable:
Tube Number
Condition
Time Start
Final Height of
Gas Bubbles
1
2
3
4
Class Data Tables:
Sugar Concentration Class Data
Sugar
Conc. (%)
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 3
Group 4
Group 5
Group 6
Group7
Average
0
5
10
20
Temperature Class Data
Temp. (°C)
0
25
40
100
Group 1
Group 2
Group7
Average
Using a line graph, show the relationship between the ​concentration of sucrose​​ and the ​height of the bubbles.
Include a title on the x and y-axis. Include the proper units and make sure your table is neat and organized. Be
sure to include a ​title, legend, axis labels, ​and​ proper units.​​ [10]
Sugar Concentration
Temperature
Analysis Questions:
1. Was there any measurable gas being produced in tube 1? Why did this tube have to be included in the
investigation?
2. How did each variable affect the rate of respiration? Why?
Variable:
Variable:
Pattern:
Pattern:
Possible Explanation:
Possible Explanation:
3. Yeast is used in making breads and other baked goods that need to rise. Sugar is commonly added to dough
as food for yeast. What would happen if you mixed dough together for a loaf of bread but did not add any
sugar? Explain your answer.