Question

Bio 101 Lab #8: All activities/questions are to be completed for a grade. Type your answers to these questions into a Microsoft word document titles ‘Lab 8 – Worksheet’.

Laboratory Experiment 8– Fermentation and Cellular Respiration

Topic

Fermentation

Materials / Equipment

You may have to purchase a few items if you don’t have them in your house.

(4) 16oz soda/water bottles; washed clean and dry

(4) Small balloon, all of the same size, but different colors.

            - Make sure to stretch the balloons by hand before using

Measuring cups and teaspoons

Hot tap water

2 packets of ‘Rapid Rise Yeast’ (each packet has about 2 teaspoons)          

White granulate sugar

Table salt

Corn Starch (1 tablespoon to a 1/4c water)

2 feet of string

1 ruler (with millimeters markings)

Background Information:                    

Yeast, a unicellular fungus, is extremely important in the baking and brewery industries because of its fermentation byproducts- carbon dioxide, which causes bread dough to rise, and ethanol (ethyl alcohol), which is found in alcoholic beverages. Unlike many organisms, yeast is capable of metabolizing by both fermentation (anaerobic respiration) and aerobic respiration processes, depending on the presence or absence of oxygen in the yeast’s environment at the time.

Procedure:

1. Write, with a marker, the number 1 on a balloon and a bottle, write a number 2 on the second balloon and on the second bottle, etc, until all balloons have a corresponding bottle with the same number.

2. Stretch your balloons with your hands, so they will easily inflate during the experiment.

3. Prepare all of the dry ingredients (as seen in #4) first and put them in the bottle, then add ¼ cup hot tap water to each bottle and quickly cover the bottles with their corresponding balloon.

4. Prepare your bottles with the dry ingredients:
   1. Bottle #1: a teaspoon of yeast.
   2. Bottle #2: a teaspoon of yeast and a teaspoon of sugar.
   3. Bottle #3: a teaspoon of yeast and a teaspoon of corn starch.
   4. Bottle #4: a teaspoon of yeast, a teaspoon of sugar, and a teaspoon of salt.

5. Add ¼ cup hot tap water to each of the bottles and quickly cover the bottle’s opening with its corresponding balloon.

6. You will be measuring the rate of fermentation by measuring the circumference with string and a ruler every 20min for a total of 80mins using the chart below.

7. Take a least one picture of you and your experiment.

Bottle	Solution Yeast + Water +… .	Gas in mm at 20 min	Gas in mm at 40 min	Gas in mm at 60 min	Gas in mm at 80 min
1 •	No sugar
2	Sugar
3	Starch
4	Sugar + salt

Questions:

1. What gas is produced by fermentation in yeast?

2. Is fermentation in yeast aerobic or anaerobic respiration?

3. Which bottle showed the most gas production at 80 minutes? Why?

4. Which tube(s) showed the least amount of gas production at 80 minutes? Why?

5. What was the purpose of the salt?

6. What do you predict would happen if you:

1. altered the "yeast food" (such as, syrup, honey, etc.)?

2. altered the water temperature ?

c. altered the size of the bottle?

Part II:

1. Watch the Bioflix that in the assignment folder.
2. After you have watch the Bioflix, select the LabBench ‘Cellular Respiration’ activity: http://www.phschool.com/science/biology_place/labbench/lab5/intro.html

Questions:

1. ___ Which of the following is a true statement based on the data?
   1. The amount of oxygen consumed by germinating corn at 22°C is approximately twice the amount of oxygen consumed by germinating corn at 12°C.
   2. The rate of oxygen consumption is the same in both germinating and non-germinating corn during the initial time period from 0 to 5 minutes.
   3. The rate of oxygen consumption in the germinating corn at 12°C at 10minutes is 0.4 ml oxygen per minute.
   4. The rate of oxygen consumption is higher for non-germinating corn at 12°C than at 22°C.
   5. If the experiment were run for 30 minutes, the rate of oxygen consumption would decreas
2. Why?
3. What is the rate oxygen consumption in germinating corn at 12^oC?
   1. 0.08ml/min
   2. 0.04ml/min
   3. 0.8ml/min
   4. 0.4ml/min
   5. 1.00ml/min
4. Why?
   1. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________
5. Which of the following conclusions is supported by the data?
   1. The rate of respiration is higher in non-germinating seeds than in germinating seeds.
   2. Non-germinating peas are not alive, and show no difference in rate of respiration at different temperatures.
   3. The rate of respiration in the germinating seeds would been higher if the experiment were conducted in sunlight.
   4. The rate of respiration increases as the temperature increases in both germinating and non-germinating seeds.
   5. The amount of oxygen consumed could be increased if pea seeds were substituted for cord seeds.
6. Why?
   1. ________________________________________________________________ ________________________________________________________________ ________________________________________________________________
7. ___ What is the role of the KOH in this experiment?
   1. It serves as an electron donor to promote cellular respiration
   2. As KOH breaks down, the oxygen needed for cellular respiration is released.
   3. It serves as a temporary energy source for the respiring organism.
   4. It binds with carbon dioxide to form a solid, preventing carbon dioxide production from affecting the gas volume.
   5. Its attraction for water will cause water to enter the respirometer.

Answer 1

Ans-1- Carbon dioxide is produced by fermentation in yeast.

Ans-2- Fermentation in yeast is anaerobic respiration.

Ans-3- The third bottle with sugar showed the most gas production at 80 minutes as it acts as a direct substrate for the yeast enzymes to act. While starch needs to be first converted into glucose inorder to be utilized.

Ans-4- The first water with no sugar showed the least amount of gas production after 80 minutes as the substrate to be converted into CO₂ is only absent.

Ans-5- Purpose of the salt is to tighten the gluten structure in the dough. Due to this salt induced tightening, gluten gains strength and thus its able to efficiently hold CO₂, released as a byproduct of fermentation.

Ans-6- Prediction of the outcomes:

• If the "yeast food" is altered, the taste of the end-products yielded will be different.
• If the temperature of the water used is altered, the kinetics of the fermentation reaction changes. It decreases with the reduced temperature and vice-versa.
• If the size of the bottle is altered, the ballons on the top of the bottles will get inflated earlier as the accomodation of CO₂ inside the bottle will be lesser.