Fermentation Post Lab Questions

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BIOL 102: Lab 7

Yeast Fermentation

PRE-LAB ASSIGNMENT:

Students are expected to read pages 1-2 before coming to the lab to complete the experiments.

Print this entire lab packet and bring it to the laboratory.

Please provide a FULL lab report for this experiment following the “Lab Report Guidelines”.

Please note that this lab report WILL include a HYPOTHESIS.

Objectives:

· Observe yeast fermentation

· Determine the optimum conditions for yeast fermentation

Background:

All fungi are eukaryotes. Although they vary in size and shape, fungi share key characteristics including their way of obtaining nutrients for growth and energy. Fungi are heterotrophs and they depend on preformed carbon molecules produced by other organisms. However, fungi do not ingest food and then digest it using enzymes; instead they invade -think of a moldy piece of bread-a food source and secrete digestive enzymes onto it. The digestion occurs outside the body. When the polymers are broken down into monomers, the fungi absorb the predigested food into its body.

Yeast are microscopic, unicellular organisms in the Kingdom Fungi. Like other fungi, yeast are incapable of making their own food, but like any other organism, need food for energy. They rely on carbohydrates (usually sugars) found in their environment to provide them with this energy so that they can grow and reproduce. There are many species of yeast, and each has a particular food source.

Regardless of the food source, yeast perform fermentation which does not utilize oxygen. In fermentation, the only energy extraction pathway is glycolysis, with one or two extra reactions tacked on at the end, but no electron transport chain. Therefore, only 2 ATPs are formed per glucose.

Fermentation and cellular respiration begin the same way, with glycolysis. In fermentation, however, the pyruvate made in glycolysis is not completely oxidized because it does not continue through the citric acid cycle and the electron transport chain does not run. Because the electron transport chain is not functional, the NADH cannot drop its electrons off to the electron transport chain, and thus very few ATP molecules are synthesized because the ATP synthase is not running.

Based on the end products, fermentation can be of two types: ALCOHOLIC fermentation (the subject of this lab) and LACTIC ACID fermentation.

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Regardless of the type of fermentation, the purpose of the extra reactions in fermentation, is to regenerate (recycle) the electron carrier NAD+ from the NADH produced in glycolysis. The extra reactions accomplish this by letting NADH drop its electrons off with an organic molecule such as acetaldehyde to produce ethanol (alcoholic fermentation), or pyruvate to produce lactic acid (lactic acid fermentation). This “drop-off” of electrons allows glycolysis to keep running by ensuring a steady supply of NAD+.

Going from pyruvate to ethanol is a two-step process. In the first step, a carboxyl group is removed from pyruvate and released as carbon dioxide, producing a two-carbon molecule called acetaldehyde. In the second step, NADH passes its electrons to acetaldehyde, regenerating NAD+ and forming ethanol.

Yeast breaks down glucose into ethanol, 2 carbon dioxide molecules, and 2 ATP molecules. The formula for the yeast fermentation reaction is:

Reactant Products

C6H12O6 >>>>>>> 2CH3CH2OH + 2CO2 + 2 ATP molecules

For the yeast cell, this chemical reaction is necessary to produce the energy for life. The ethanol and the carbon dioxide are waste products. It is these waste products that we take advantage of: we use the ethanol in alcoholic beverages and the carbon dioxide makes bread rise when baking.

Alcoholic fermentation, can be observed and measured by using the amount of carbon dioxide gas that is produced from the breakdown of glucose. In this exercise, you will observe alcoholic fermentation by yeast. To do so you will add the same amounts of yeast and water to different amounts of sugar in Erlenmeyer flasks and cap them with a balloon to see how much carbon dioxide gas is produced. You will also use water at two different temperatures and determine how much carbon dioxide is produced. The more fermentation that occurs, the more carbon dioxide will be produced, and the more the balloon will expand.

Information adapted from:

Solomon, Eldra P. et al. Biology. 10th ed. Cengage, 2015.

https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation

LAB DATASHEET

Determine the optimum conditions for yeast fermentation.

Think Scientifically:

Please explain your rationale to which flask or test variable will produce the most CO2. Look at the various bottles below and state whether bottle A-F will produce the most CO2 and explain why.

Materials:

Sugar

Dry yeast

Warm water

Ice cold water

Balance scale

Measuring spoons

100 mL Graduated Cylinder

6 Erlenmeyer flasks

6 Rubber bands

6 Balloons

Ruler

Procedure:

1. Obtain 6 labeled Erlenmeyer flasks.

2. Fill each flask accordingly:

· Bottle A – 5 mL sugar, 3 grams of dry yeast

· Bottle B – 10 mL sugar, 3 grams of dry yeast

· Bottle C – 15 mL sugar, 3 grams of dry yeast

· Bottle D – 5 mL sugar, 3 grams of dry yeast

· Bottle E – 3 grams of dry yeast

· Bottle F – 15 mL sugar

3. Fill all flasks except D with 100 mL of warm water. Fill flask D with 100 mL of ice cold water.

4. Place a balloon over the top of each flask and tighten it with a rubber band.

5. Swirl flask to mix contents. Wait 20-30 minutes.

6. Record observations in Table 1.

7. Measure the width and height of the balloon (from the top of the flask to the top of the balloon) with a ruler, and record it in Table 1.

8. Graph the Sugar Quantity vs. Balloon Height in an X-Y Scatterplot. Insert DIGITAL scatterplot only. Written graphs and/or pictures of written graphs will not be accepted.

Table 1: Observations and Measurements of Balloon height in cm
Flask Observations Height Width
A 1st to rise 4.5inch 2inch
B 3rd to rise 3.8inch 1.5inch
C 2nd to rise 4.2inch 1.8inch
D Did not rise 0 0
E Did not rise 0 0
F Did not rise 0 0

Conclusion:

Be sure to address the following:

· How did your original rationale compare to the data collected? If your rationale was incorrect, why do you think it did not produce the most CO2?

· Describe what happened in this reaction using the following terms: yeast, warm water, cold water, sugar, anaerobic respiration, and carbon dioxide.

· Compare what happened to each of the balloons for flasks A through F. Which flask had the most CO2 production? Least? How do you know? Be sure to describe WHY!

· There were four experimental flasks and two control flasks in this exercise. Which flasks were the experimental and which were the control flasks? Explain how each determination was made.

 
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UMUC Biology 102 / 103 Lab 3: Cell Structure And Function ANSWER KEY

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This contains 100% correct material for UMUC Biology 103 LAB03. However, this is an Answer Key, which means, you should put it in your own words. Here is a sample for the Pre lab questions answered:

Pre-Lab Questions

1. Identify the major similarities and differences between prokaryotic and eukaryotic cells. (2 pts)

Prokaryotes tend to be less complex than eukaryotic cells, with fewer organelles and (generally) fewer requirements for survival. Eukaryotes have a nucleus, while prokaryotes do not. Both eukaryotes and prokaryotes have DNA, a cell membrane, and cytoplasm.

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell? (2 pts)

DNA is housed in the nucleus in eukaryotic cells. Prokaryotic cells do not have a nucleus, and thus DNA exists freely in the cytoplasm.

3. Identify three structures which provide support and protection in a eukaryotic cell. (2 pts)

The cell membrane, the cytoplasm, and the cytoskeleton (microtubules, microfilaments, etc.).

The rest of the questions are answered as well:

Onion Root Tip 100X g (Small)

Experiment 1: Cell Structure and Function

Post-Lab Questions

1. Label each of the arrows in the following slide image:

2. What is the difference between the rough and smooth endoplasmic reticulum?

3. Would an animal cell be able to survive without a mitochondria? Why or why not?

4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria?

5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.

Experiment 2: Osmosis – Direction and Concentration Gradients

Data Tables and Post-Lab Assessment

Table 3: Sucrose Concentration vs. Tubing Permeability

Band Color

Sucrose %

Initial Volume (mL)

Final Volume (mL)

Net Displacement (mL)

Yellow

Red

Blue

Green

Hypothesis:

Post-Lab Questions

1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.

2. Which tubing increased the most in volume? Explain why this happened.

3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?

4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body? Be sure to explain how this process works in terms of tonicity.

6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be? Explain your answer using scientific evidence.

7. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.

Your Full Name:

UMUC Biology 102/103

Lab 3: Cell Structure and Function

INSTRUCTIONS:

 

· On your own and without assistance, complete this Lab 3 Answer Sheet electronically and submit it via the Assignments Folder by the date listed in the Course Schedule (under Syllabus).

· To conduct your laboratory exercises, use the Laboratory Manual located under Course Content. Read the introduction and the directions for each exercise/experiment carefully before completing the exercises/experiments and answering the questions.

· Save your Lab 3 Answer Sheet in the following format: LastName_Lab3 (e.g., Smith_Lab3).

· You should submit your document as a Word (.doc or .docx) or Rich Text Format (.rtf) file for best compatibility.

 

Pre-Lab Questions

1. Identify the major similarities and differences between prokaryotic and eukaryotic cells.

 

 

 

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?

 

 

 

3. Identify three structures which provide support and protection in a eukaryotic cell.

 

 

Onion Root Tip 100X g (Small) Experiment 1: Cell Structure and Function

Onion Root Tip: 1000X

A

B

C

D

 

Post-Lab Questions

1. Label each of the arrows in the following slide image:

 

 

2. What is the difference between the rough and smooth endoplasmic reticulum?

 

 

 

3. Would an animal cell be able to survive without a mitochondria? Why or why not?

 

 

 

4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria?

 

 

 

5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.

 

 

 

 

 

Experiment 2: Osmosis – Direction and Concentration Gradients

Data Tables and Post-Lab Assessment

Table 3: Sucrose Concentration vs. Tubing Permeability

Band Color Sucrose % Initial Volume (mL) Final Volume (mL) Net Displacement (mL)
Yellow        
Red        
Blue        
Green        

 

Hypothesis:

 

 

 

 

Post-Lab Questions

1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.

 

2. Which tubing increased the most in volume? Explain why this happened.

 

 

 

 

3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?

 

 

 

4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

 

 

 

5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body? Be sure to explain how this process works in terms of tonicity.

 

 

 

6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be? Explain your answer using scientific evidence.

 

 

 

7. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.

© eScience Labs, LLC 2014

 
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Biology 2 – Hierarchies Of Life Lab Questions

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Hierarchies of Life
Experiment 1: Classification of Common Objects
Data Tables (15 points)

Post-Lab Questions
1. Did you find that the items grouped together as you worked down the flow chart had similar characteristics in terms of their appearance? What about function? (10 points)

A lot of the groups had similar characteristics and function, until I looked deeper into then as I continued down the list of questions. For example, a candle and a Scentsy are similar in function and characteristics, as they both give off pleasant smells. But if you were to ask if they use fire, you’d be able to differentiate the two.

2. Do you feel that the questions asked were appropriate? What questions would you have asked to devise this classification flow chart? What objects would be grouped together with your system? (10 points)

I had to look over the chart a few times and soon made sense of the flow. I found myself conflicted on some of the answers as well, not agreeing with some entirely. For example, I don’t think a hex nut is cylindrical or round. It has sides, similar to pens and pencils where the style if hex like.

3. Do you think it is more or less challenging to classify living organisms in comparison to objects? Why? (10 points)

4. Pick 10 household items (e.g. spoon, book, paper clip, etc.) and design a taxonomic classification system to categorize them, similar to the one in Figure 8. Make sure you ask enough yes/no questions so that each item ends up in its own box or category at the end. (10 points)

Experiment 2: Classification of Organisms
Data Tables (10 points)
Table 2: Classification of Organisms

Organism

Domain

Kingdom

Defined Nucleus

Mobile

Photosynthesis

Unicellular

Salmonella

Bacteria

Genus

No

Yes

Yes

Yes

Ants

Eukarya

Animalia

Yes

Yes

No

No

Zoo Flagellate

Eukarya

Protozoa

Yes

Yes

No

Yes

Wolf

Eukarya

Animalia

Yes

Yes

No

No

Morning Glory

Eukarya

Plantae

Yes

No

Yes

No

Euglena

Eukarya

Protozoa

Yes

Yes

Yes

Yes

Shiitake

Eukarya

Fungi

Yes

No

No

No

Pseudomonas

Bacteria

Bacteria

No

Yes

No

Yes

Spruce

Eukarya

Planta

Yes

No

Yes

No

Death Cap Mushroom

Eukarya

Fungi

Yes

No

No

No

Post-Lab Questions
1. Did this series of questions correctly organize each organism? Why or why not? (10 points)

2. Do you feel that the questions asked were appropriate? What questions would you have asked? (10 points)

3. Which kingdom do you believe is most challenging to categorize correctly? Explain your answer (10 points)

©eScience Labs, LLC 2018

 
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Enzymes: Temperature, PH, And Specificity Hands-On Labs, Inc.

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0Enzymes: Temperature, pH, and Specificity
Hands-On Labs, Inc.  Version 42-0054-00-01
Lab Report Assistant                                                                                               This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.
Exercise 1: Enzyme Specificity
Observations
Data Table 1: Glucose Concentration
Wells Concentration of Glucose
a
b
c
d
e

Questions

A.  What determines a person’s ability to digest lactose?
B.   Which of the wells showed a positive result for glucose? Explain the results.
C.   Explain why testing for glucose is used to determine the activity of the enzyme lactase.
D.  Explain the experimental conditions for the five different wells.

Data Table 2: Presence of glucose in wells indicating lactase activity at various temperatures
Well Time (min) Concentration of Glucose

a 5
10
15
20
b 5
10
15
20
c 5
10
15
20
Exercise 2: Enzymes and Temperature
Observations

Questions:
A.  Graph the effect of temperature on the activity of the enzyme lactase.
B.   What happens when an enzyme is boiled? Is this effect reversible?
C.   Based on your experiment results, what is the optimal temperature for lactase function?
D.  Explain what happens as far as the effectiveness of the enzyme at the freezing temperature. Can this effect be overcome when the temperature rises?

Exercise 3: Enzymes and pH
Observations

Data Table 3: Glucose in wells a-d indicates enzyme activity at various pH levels
Well pH Concentration of Glucose
a 3.5
b 5.0
c 6.8
d 11.0

Questions
A.  Graph the data placing glucose concentrations on the y-axis and the pH values on the x-axis.
B.   What was the effect of pH on the enzyme lactase? Is this true for all enzymes?

 
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