Biology Lab Work 4 Assistance

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UMUC Biology 102/103

Lab 4: Enzymes

INSTRUCTIONS:

·         On your own and without assistance, complete this Lab 4 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 4 Answer Sheet in the following format:  LastName_Lab4 (e.g., Smith_Lab4).

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

Pre-Lab Questions

  1. How could you test to see if an enzyme was completely saturated during an experiment?
  2. List three conditions that would alter the activity of an enzyme. Be specific with your explanation.
  3. Take a look around your house and identify household products that work by means of an enzyme. Name the products, and indicate how you know they work with an enzyme.

Experiment 1: Enzymes in Food

Data Tables and Post-Lab Assessment

Table 1: Substance vs. Starch Presence

Table 1: Substance vs. Starch Presence
Substance Resulting Color Presence of Starch?
Positive Control: Ginger Root    
Negative Control: Student Must Select    
Food Product:    
Food Product:    
Saliva:    

Post-Lab Questions

 

  1. What were your controls for this experiment? What did they demonstrate? Why was saliva included in this experiment?
  2. What is the function of amylase? What does amylase do to starch?
  3. Which of the foods that you tested contained amylase? Which did not? What experimental evidence supports your claim?
  4. Saliva does not contain amylase until babies are two months old. How could this affect an infant’s digestive requirements?
  5. There is another digestive enzyme (other than salivary amylase) that is secreted by the salivary glands. Research to determine what this enzyme is called. What substrate does it act on? Where in the body does it become activated, and why?
  6. Digestive enzymes in the gut include proteases, which digest proteins. Why don’t these enzymes digest the stomach and small intestine, which are partially composed of protein?

Experiment 2: Effect of Temperature on Enzyme Activity

Data Tables and Post-Lab Assessment

Table 2: Balloon Circumference vs. Temperature

Table 2: Balloon Circumference vs. Temperature
Tube Temperature (°C) Uninflated Balloon Circumference (cm) Final Balloon Circumference (cm) Difference in Balloon Circumference (cm)
1 – (Cold)        
2 – (RT)      
3 – (Hot)      

 

 

Post-Lab Questions

  1. What reaction is being catalyzed in this experiment?
  2. What is the enzyme in this experiment? What is the substrate?
  3. What is the independent variable in this experiment? What is the dependent variable?
  4. How does the temperature affect enzyme function? Use evidence from your data to support your answer.
  5. Draw a graph of balloon diameter vs. temperature. What is the correlation?
  6. Is there a negative control in this experiment? If yes, identify the control. If no, suggest how you could revise the experiment to include a negative control.
  7. In general, how would an increase in substrate alter enzyme activity? Draw a graph to illustrate this relationship.
  8. Design an experiment to determine the optimal temperature for enzyme function, complete with controls. Where would you find the enzymes for this experiment? What substrate would you use?
 
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UMUC Biology 102 / 103 Lab 3: Cell Structure And Function ANSWER KEY

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Home>Homework Answsers>Biology homework help

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.

 
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Microscopy For Microbiology – Use And Function Hands-On Labs, Inc. Version 42-0249-00-02

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Microscopy for Microbiology – Use and Function

Hands-On Labs, Inc. Version 42-0249-00-02

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: Getting to Know your Compound Microscope

Data Table 1. Microscope Components.

Letter Component Name Component Function
A    
B    
C    
D    
E    
F    
G    
H    
I    
J    
K    
L    
M    

 

Data Table 2. Total Magnification.

Lens Ocular Magnification Objective Magnification Total Magnification
Scanning      
Low Power      
High Power      
Oil Immersion      

Data Table 3. Field of View.

Lens Total Magnification Field of View (mm) Field of View (µM)
Scanning      
Low Power      
High Power      
Oil Immersion      

 

Data Table 4. Letter e Viewing Results.

Lens Photograph Observations
Scanning    
Low    
High    
Oil Immersion    

 

Questions

A. Describe the details in the slides “Letter e” that become visible as the power changed from scanning power, to low power, to high power.

B. Why is it important to calculate the diameter of the field when first using the microscope?

Exercise 2: Viewing Prepared Microbe Slides

Data Table 5. Prepared Slide Viewing Results.

Slide Photograph Total Magnification
Amoeba  

 

 

  
Penicillium  

 

  
Yeast  

 

 

  
Spirillium  

 

 

  
Bacillus  

 

 

  
Coccus  

 

 

  

 

Questions

A. Using the field of view calculated in Exercise 1 for the high power lens, approximately how far across are each of the cells in the Bacteria Coccus Form slide in Data Table 5? Show your calculations.

B. Detail techniques you found helpful for focusing on the various slides in this exercise.

Exercise 3: Preparing Wet-Mount Slides

Data Table 6. Wet-Mount Viewing Results.

Slide Photograph Total Magnification
Cheek Cell Smear  

 

 

  
Dental Tatar Smear  

 

 

  

 

Questions

A. Describe the similarities and differences between the cheek cell wet mount and dental plaque wet mount.

B. How did the process of preparing wet-mount slides become easier as you prepared the second wet-mount slide of this exercise?

 
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BIO GENETICS LAB 2 QUESTIONS HELP

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NEED HELP WITH BLANK BOX QUESTION

(question 1 and 4 in conclusion part. )

* It would be nice if you can check my answeres too.

NOTES:

Tube Sample Lane

1 1 kb DNA ladder 1

2 Mother’s DNA 2

3 Child’s DNA 3

4 A.F. #1 DNA 4

5 A.F. #2 DNA 5

Record the distance each ladder band moved from the well in mm along with the size of the DNA fragments in that band in bp units, based on the bp given in step 19 , in your Lab Notes.

Lane 1:

1,000 bp 34 mm

900 bp 36 mm

800 bp 38 mm

700 bp 40 mm

600 bp 43 mm

500 bp 47 mm

400 bp 51 mm

300 bp 56 mm

250 bp 60 mm

200 bp 64 mm

150 bp 69 mm

100 bp 77 mm

50 bp 90 mm

Lane 2:

37 mm 850bp

59 mm 265bp

Lane 3:

37 mm 850bp

44 mm 575bp

Lane 4:

41 mm 670bp

43 mm 600bp

Lane 5:

44 mm 575bp

55 mm 320bp

Experiment: Agarose Gel Electrophoresis of DNA Fragments

Lab Results

  1. List the distances traveled in mm for the bands in the DNA ladder in the table below.
    Remember, smaller fragments travel farther than longer ones, so the top-most band will be the 1,000 bp sized DNA fragments whereas the bottom-most band will be the 50 bp sized DNA fragments. 

    DNA Ladder
    Band Distance (mm)
    50 bp  90 mm
    100 bp  77 mm
    150 bp  69 mm
    200 bp  64 mm
    250 bp  60 mm
    300 bp  56 mm
    400 bp  51 mm
    500 bp  47 mm
    600 bp 43 mm
    700 bp 40 mm
    800 bp 38 mm
    900 bp 36 mm
    1,000 bp 34 mm
  2. Whose sample had the approximately 570 bp and 320 bp sized DNA fragments?
     A.F. #2
  3. What were the sizes of the DNA fragments for alleged father #1?
    41 mm 670bp

    43 mm 600bp

Data Analysis

  1. Which size DNA fragment did the child inherit from her mother?
     37 mm 850bp
  2. Which alleged father, if any, can be definitively ruled out as the child’s biological father?
     A.F. #2

Conclusions

  1. How are new molecules of DNA synthesized in living cells?
  2. What is the function of DNA?
     

    DNA has genetic information that controls our cells. So, DNA is like a blueprint that shows how to construct components of cells like proteins and ribonucleic acid (RNA). This information is carried down to newer generations through inheritance.
  3. If each individual has such a small amount of DNA in their cells, how do the bands on the gel contain enough DNA to be visible?
      In order to make DNA visible. The Gel has to be soaked in a dye (ethidium bromide) to bind with the DNA and rinsed off after. Ethidium bromide helps to make DNA visible by glowing brightly in UV rays.
  4. Humans only have a few eye colors and only four ABO-based blood types. How can DNA tests definitively identify individuals when many people have brown eyes or type A blood?
  5. Suppose a suspicious hair was found in a victim’s home. A gel is set up with the DNA fragments of two suspected criminals in lanes 4 and 5, the DNA fragments of the suspicious hair in lane 3, and the victim’s DNA fragments, as a negative control, are in lane 2. A DNA ladder is in lane 1. The resulting gel is below. Which suspect, if any, committed the crime? Explain your answer.
 
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Biology Lab Assignments

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Lab 2 Cell Structure and Function BIO101L

Student Name: Click here to enter text.

Access Code (located on the lid of your lab kit): Click here to enter text.

Pre-Lab Questions

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

Click here to enter text.

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.

Experiment 1: Identifying Cell Structures

Post-Lab Questions

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

Structure Identity
A Click here to enter text.
B Click here to enter text.
C Click here to enter text.
D Click here to enter text.

 

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

3. Would an animal cell be able to survive without 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: Create a Cell

Post-Lab Questions

1. What cell structures did you place in the plant cell that you did not place in the animal cell?

2. Is there any difference in the structure of the two cells?

3. What structures do cells have for support in organisms that lack cell walls?

4. How are organelles in a cell like organs in a human body?

5. How does the structure of a cell suggest its function? List three examples.

6. In the table below, list the items you used to represent the various organelles in your ANIMAL cell. Provide a brief rationale explaining why you selected each item.

Item Organelle Rationale
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7. Insert picture of your ANIMAL cell with your name and access code handwritten in the background.

8. In the table below, list the items you used to represent the various organelles in your PLANT cell. Provide a brief rationale explaining why you selected each item.

Item Organelle Rationale
Click here to enter text. Click here to enter text. Click here to enter text.
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9. Insert picture of your PLANT cell with your name and access code handwritten in the background.

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Anthropology Exam

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Beginning Thoughts on Anthropology, Culture & Cultural Diversity

1.)What ideas or images that come to mind if someone says “Anthropology” or “anthropologist”? What has shaped your ideas about what Anthropology is or what Anthropologists do?

2.)What IS Anthropology? And what are the four sub-fields of Anthropology?

3.)Some contemporary archaeologists focus on studying modern human waste….including e-waste. If someone were to study YOUR waste (trash) …and e-waste what would they learn about you? Your diet? Your lifestyle?

4.) What are some cultural adaptations human beings have to better allow them to survive in their environment? Are there negative effects of these adaptations? If so, do the benefits outweigh those negative effects?

5.)American anthropologist Ralph Linton once said “The last thing a fish would ever notice would be water.” (Ralph Linton, 1936) How is this relevant and applicable to a discussion on “culture”?

6.) Polish anthropologist, Bronislaw Malinowski who is credited with inventing the anthropological method of intensive fieldwork, wrote in his journal about his fieldwork in the Trobriand Islands.In his diary he wrote” Imagine yourself suddenly set down surrounded by all your gear, alone on a tropical beach close to a native village, while the launch or dinghy which has brought you sails away out of sight.” What is Malinowski describing? Have you ever had an analogous experience in Philadelphia (or elsewhere)?

7.)Clifford Geertz, one of the most influential American anthropologists in the last 40 years, said “The locus of study is not the object of study. Anthropologists don’t study villages (tribes, neighborhoods…) they study in villages.” What do you think he meant? (And what happens if you substitute college for village?)

8.) If I were to ask you to provide a “socio-cultural analysis” of this classroom…where would you begin? Can you identify 10 ways that you might consider “diversity” within this classroom? (on campus, in the city, in the U.S. or in the world?)

9.) How do you think about diversity? i.e.as a problem? A challenge? An asset? Explain

10.) What do you think is bigger…a nation-state or a culture? Briefly explain.

 
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Biology Lab

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Lab 2 Cell Structure and Function BIO101L

Student Name: Click here to enter text.

Access Code (located on the lid of your lab kit): Click here to enter text.

Pre-Lab Questions

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

Click here to enter text.

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.

Experiment 1: Identifying Cell Structures

Post-Lab Questions

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

 

Structure Identity
A Click here to enter text.
B Click here to enter text.
C Click here to enter text.
D Click here to enter text.

 

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

3. Would an animal cell be able to survive without 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: Create a Cell

Post-Lab Questions

1. What cell structures did you place in the plant cell that you did not place in the animal cell?

2. Is there any difference in the structure of the two cells?

3. What structures do cells have for support in organisms that lack cell walls?

4. How are organelles in a cell like organs in a human body?

5. How does the structure of a cell suggest its function? List three examples

6. In the table below, list the items you used to represent the various organelles in your ANIMAL cell. Provide a brief rationale explaining why you selected each item.

Item Organelle Rationale
Click here to enter text. Click here to enter text. Click here to enter text.
Click here to enter text. Click here to enter text. Click here to enter text.
Click here to enter text. Click here to enter text. Click here to enter text.
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7. Insert picture of your ANIMAL cell with your name and access code handwritten in the background.

8. In the table below, list the items you used to represent the various organelles in your PLANT cell. Provide a brief rationale explaining why you selected each item.

Item Organelle Rationale
Click here to enter text. Click here to enter text. Click here to enter text.
Click here to enter text. Click here to enter text. Click here to enter text.
Click here to enter text. Click here to enter text. Click here to enter text.
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Click here to enter text. Click here to enter text. Click here to enter text.

 

9. Insert a picture of your PLANT cell with your name and access code handwritten in the background.

 
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Case Study

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“Can Suminoe Oysters Save Chesapeake Bay?” by Nieman & Liu Page 

Annapolis, January 2008 “If you don’t do the right thing, we will take matters into our own hands.”

State Senator Ben Fisher hung up the phone slowly. ” at was one of his constituents, one of the many he had heard from that day, each one angrier than the last it seemed. His was the swing vote on the Assembly bill funding the full-scale introduction of sterile Suminoe oysters to the Maryland side of the Chesapeake Bay. ” e bill was an attempt to try to off -set the eff ects of declining populations of native oysters in the bay, the result of habitat degradation, over-harvesting, and disease. Introducing the Suminoe oysters would be an expensive and risky undertaking, but there were costs—both environmental and economic—of doing nothing, too.

Environmentalists were divided, “clean” versus “pristine.” Some demanded widespread seeding of the imported oysters to deal with worsening water quality that was wiping out aquatic life in the bay. Others warned that this could be a bigger disaster than kudzu. Test introductions in Virginia had been limited and closely monitored—and so far so good. But scientists warned that a few oysters would be fertile and might proliferate, forcing out the last of the Eastern oysters or interbreeding with the native species – bringing who knew what changes to the already damaged ecosystem?

Ben gazed out his offi ce window. “CLEAR THE BAY!” said one of the banners that blocked his view of the sailboats in the harbor. “DON’T TINKER WITH A NATIONAL TREASURE!” warned another.

Business interests held all sorts of positions. “We’d rather see those tax dollars go into developing infrastructure for high-end development,” a major developer with plans for summer homes, condos and retail shops had emailed Ben. “Do you know what that land is worth under those broken-down, abandoned fi shing shacks?” He didn’t need to add that he put a lot of money into political campaigns.

” e owner of a fi sh market had called earlier in the day, worried that the oysters, whether native or otherwise, might not be fi t for eating as a result of all the pollution they fi ltered from the water. She had few oysters to sell now—would the new ones appeal to customers?

” e Delmarva Peninsula poultry producers didn’t want any more controls on the nutrient load entering the bay. ” ey felt there were too many controls as it was, and warned that more controls would hamper their operations. ” ey were all in favor of the oysters as a solution. So were the charter-boat owners who wanted clear water for the rockfi sh.

The commercial fishing industry wanted the oysters too, and now. Boats were idled and processing plants were handling trucked-in Louisiana oysters. The biggest plant in Ben’s district said it would close this year if things didn’t change. These new oysters grew three times as fast, they said. It wasn’t too late to save an industry.

Can Suminoe Oysters Save Chesapeake Bay? by Valerie Nieman Department of English Department of Journalism and Mass Communication North Carolina A&T State University Zhi-Jun Liu Department of Geography University of North Carolina—Greensboro

“Can Suminoe Oysters Save Chesapeake Bay?” by Nieman & Liu Page 

Image Credit: Copyright © Robert Kyllo. Copyright ©  by the National Center for Case Study Teaching in Science. Originally published // at http://www.sciencecases.org/chesapeake_bay/chesapeake_bay.asp Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

On the other hand, the State of North Carolina was threatening a lawsuit, fearful that the nonnative oysters would spread down the coast and aff ect their beds. ” ey cited the destructive virus brought in by oyster introductions decades ago.

And many of Ben’s constituents were in an uproar over the expense that Marylanders would bear for the oyster option—or the alternative. Towns and cities didn’t want to spend money to upgrade their sewer systems when so much pollution came from out-of-state.

Even within the Senator’s own family there was division. His father, who had started tonging oysters when he was a boy, said it was time to let the old ways go, that fi shing was no way to make a living these days. Spend the money elsewhere. His daughter, a member of a cultural preservation group, pleaded: “We need to preserve the watermen culture. We need the oysters.”

And now this dramatic phone call—desperate people threatening to take the matter into their own hands and dump imported oysters—nonsterile ones that could reproduce and spread—into the bay to restore the beds. ” e debate had dragged on too long, they said. A decision had to be made.

Senator Ben Fisher left his offi ce and walked down the echoing hall to the Assembly chamber, where he would have to cast his vote.

Questions . Who is being aff ected by this decision and how? . If the decision is made to introduce the Suminoe oysters, what might be the long-term eff ects on

the environment, the communities, the people? . Any choice implies other lost opportunities. In what alternative ways might this money be spent

to deal with the Chesapeake Bay’s problems and serve constituents? . What might this region look like in  years if nothing is done? . What should Senator Ben Fisher do?

 
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Microbiology Lab Report- Gram Staining, Simple Staining, Negative Staining

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1. Do a search online 1-2 antibiotics that affect Gram-positive bacteria and list them. On what part of the cell do the antibiotics usually work? List one or two antibiotics that affect Gram-negative bacteria? On what part of the cell do the antibiotics usually work? (Be sure to cite your sources in your answer.) (5 points)

2. Why do you think it is important to identify a bacterial disease in a patient before prescribing any antibiotic treatments? (Be specific.) (5 points)

3.   What are some of the limitations of simple staining? (5 points)

4.   Give an example of a situation in a lab or medical setting in which simple staining would be utilized. (5 points)

5.   So far in this lab, you have used one type of simple stain(Crystal violet) and one type of negative stain (Nigrosin), yet there are many other simple and negative dyes available. Pick one simple dye and one negative dye, and discuss how those dyes differ from the ones you used in this lab. Give a scenario in which their use would be appropriate. (5 points)

6. Using either a textbook or a reputable online resource, research some of the typical characteristics of bacteria, and discuss why it might be important for a researcher or a hospital technician to be able to differentiate between Gram-positive and Gram-negative bacteria. (5 points)

 
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Lab Report

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Experiment 2: Concentration Gradients and Membrane Permeability

In this experiment, you will dialyze a solution of glucose and starch to observe:

  • The directional movement of glucose and starch.
  • The effect of a selectively permeable membrane on the diffusion of these molecules.

An indicator is a substance that changes color when in the presence of a specific substance. In this experiment, IKI will be used as an indicator to test for the presence of starch.

 

Materials

(5) 100 mL Beakers
10 mL 1% Glucose Solution, C6H12O6
4 Glucose Test Strips
(1) 100 mL Graduated Cylinder
4 mL 1% Iodine-Potassium Iodide, IKI
5 mL Liquid Starch, C6H10O5
3 Pipettes
4 Rubber Bands (Small; contain latex, handle with gloves on if allergic)

  

 

Permanent Marker
*Stopwatch
*Water
*Scissors

*15.0 cm Dialysis Tubing

*You Must Provide
*Be sure to measure and cut only the length you need for this experiment. Reserve the remainder for later experiments.

 

 

    

 

Attention!

Do not allow the open end of the dialysis tubing to fall into the beaker. If it does, remove the tube and rinse thoroughly with water before refilling it with the starch/glucose solution and replacing it in the beaker.

 
Note:

If you make a mistake, the dialysis tubing can be rinsed and used again.

Dialysis tubing must be soaked in water before you will be able to open it up to create the dialysis “bag.” Follow these directions for this experiment:

1.      Soak the tubing in a beaker of water for ten minutes.

2.     Place the dialysis tubing between your thumb and forefinger, and rub the two digits together in a shearing manner. This motion should open up the “tube” so that you can fill it with the different solutions.

 

Procedure

1.     Measure and pour 50 mL of water into a 100 mL beaker using the 100 mL graduated cylinder. Cut a piece of dialysis tubing 15.0 cm long. Submerge the dialysis tubing in the water for at least ten minutes.

2.     Measure and pour 82 mL of water into a second 100 mL beaker using the 100 mL graduated cylinder. This is the beaker you will put the filled dialysis bag into in Step 9.

3.     Make the glucose/sucrose mixture. Use a graduated pipette to add 5 mL of glucose solution to a third 100 mL beaker and label it “dialysis bag solution.” Use a different graduated pipette to add 5 mL of starch solution to the same beaker. Mix by pipetting the solution up and down six times.

4.     Using the same pipette that you used to mix the dialysis bag solution, remove 2 mL of the dialysis bag solution and place it in a clean beaker. This sample will serve as your positive control for glucose and starch.

a.     Dip one of the glucose test strips into the 2 mL of glucose/starch solution in the third beaker. After one minute has passed, record the final color of the glucose test strip in Table 3. This is your positive control for glucose.

b.     Use a pipette to transfer approximately 0.5 mL of IKI into the 2 mL of glucose/starch solution into the third beaker. After one minute has passed, record the final color of the glucose/starch solution in the beaker in Table 3. This is your positive control for starch.

5.     Using a clean pipette, remove 2 mL of water from the 82 mL of water you placed in a beaker in Step 2, and place it in a clean beaker. This sample will serve as your negative controls for glucose and starch.

a.     Dip one of the glucose test strips into the 2 mL of water in the beaker. After one minute has passed, record the final color of the glucose test strip in Table 3. This is your negative control for glucose.

b.     Use a pipette to transfer approximately 0.5 mL of IKI into the 2 mL in the beaker. After one minute has passed, record the final color of the water in the beaker      in Table 3. This is your negative control for starch.

Note:The color results of these controls determine the indicator reagent key. You must use these results to interpret the rest of your results.

6.     After at least ten minutes have passed, remove the dialysis tube and close one end by folding over 3.0 cm of one end (bottom). Fold it again and secure with a rubber band (use two rubber bands if necessary).

7.     Test to make sure the closed end of the dialysis tube will not allow solution to leak out. Dry off the outside of the dialysis tube bag with a cloth or paper towel. Then, add a small amount of water to the bag and examine the rubber band seal for leakage. Be sure to remove the water from the inside of the bag before continuing.

  1. Using the same pipette that was used to mix the solution in Step 3, transfer 8 mL of the dialysis bag solution to the prepared dialysis bag.
Figure 4: Step 9 reference.
Figure 4:Step 9 reference.

9.     Place the filled dialysis bag in the 100 mL beaker filled with 80 mL of water, leaving the open end draped over the edge of the beaker as shown in Figure 4.

10.Allow the solution to sit for 60 minutes. Clean and dry all materials except the beaker holding the dialysis bag.

11.After the solution has diffused for 60 minutes, remove the dialysis bag from the beaker and empty the contents of the bag into a clean, dry beaker. Label the beaker “final dialysis bag solution.”

12.Test the final dialysis bag solution for the presence of glucose by dipping one glucose test strip into the dialysis bag. Wait one minute before reading the results of the test strip. Record your results for the presence of glucose in Table 4.

13.Test for the presence of starch by adding 2 mL IKI. After one minute has passed, record the final color in Table 4.

14.Use a pipette to transfer 8 mL of the water in the beaker to a clean beaker. Test the beaker water for the presence of glucose by dipping one glucose test strip into the beaker. Wait one minute before reading the results of the test strip, and record the results in Table 4.

15.Test for the presence of starch by adding 2 mL of IKI to the beaker water. Record the final color of the beaker solution in Table 4.

Table 3: Indicator Reagent Data
Indicator Starch Positive
Control (Color)		 Starch Negative
Control (Color)		 Glucose Positive
Control (Color)		 Glucose Negative
Control (Color)
Glucose Test Strip n/a n/a    
IKI Solution     n/a n/a

 

Table 4: Diffusion of Starch and Glucose Over Time
Indicator Dialysis Bag After 60 Minutes Beaker Water After 60 Minutes
IKI Solution    
Glucose Test Strip    

 

Post-Lab Questions

1.     Why is it necessary to have positive and negative controls in this experiment?

2.     Draw a diagram of the experimental set-up. Use arrows to depict the movement of each substance in the dialysis bag and the beaker.

3.     Which substance(s) crossed the dialysis membrane? Support your response with data-based evidence.

4.     Which molecules remained inside of the dialysis bag?

5.     Did all of the molecules diffuse out of the bag into the beaker? Why or why not?

 

Experiment 1: Diffusion through a Liquid

In this experiment, you will observe the effect that different molecular weights have on the ability of dye to travel through a viscous medium.

Materials

1 60 mL Corn Syrup Bottle, C12H22O11
Red and Blue Dye Solutions (Blue molecular weight = 793 g/mole; red molecular weight = 496 g/mole)
(1) 9 cm Petri Dish (top and bottom halves)

  

Ruler
*Stopwatch
*Clear Tape

*You Must Provide

 

Procedure

1.     Use clear tape to secure one-half of the petri dish (either the bottom or the top half) over a ruler. Make sure that you can read the measurement markings on the ruler through the petri dish. The dish should be positioned with the open end of the dish facing upwards.

  1. Carefully fill the half of the petri dish with corn syrup until the entire surface is covered.
  2. Develop a hypothesis regarding which color dye you believe will diffuse faster across the corn syrup and why. Record this in the post-lab questions.
  3. Place a single drop of blue dye in the middle of the corn syrup. Note the position where the dye fell by reading the location of its outside edge on the ruler.
  4. Record the location of the outside edge of the dye (the distance it has traveled) every ten seconds for a total of two minutes. Record your data in Table 1 and use your results to perform the calculations in Table 2.
  5. Repeat the procedure using the red dye, the unused half of the petri dish, and fresh corn syrup.

 

Table 1: Rate of Diffusion in Corn Syrup
Time (sec) Blue Dye Red Dye Time (sec) Blue Dye Red Dye
10     70    
20     80    
30     90    
40     100    
50     110    
60     120    
           

 

Table 2: Speed of Diffusion of Different Molecular Weight Dyes
Structure Molecular Weight Total Distance
Traveled (mm)		 Speed of Diffusion
(mm/hr)*
Blue Dye      
Red Dye      

*Multiply the total distance diffused by 30 to get the hourly diffusion rate

 

Post-Lab Questions

  1. Record your hypothesis from Step 3 here. Be sure to validate your predictions with scientific reasoning.
  2. Which dye diffused the fastest?
  3. Does the rate of diffusion correspond with the molecular weight of the dye?
  4. Does the rate of diffusion change over time? Why or why not?
  5. Examine the graph below. Does it match the data you recorded in Table 2? Explain why, or why not. Submit your own plot if necessary.

https://nuonline.neu.edu/bbcswebdav/pid-9451339-dt-content-rid-14232100_1/courses/BIO1101.90155.201714/BIO1101.90155.201714_ImportedContent_20160930044714/CourseRoot/html/lab006s001.html

https://nuonline.neu.edu/bbcswebdav/pid-9451340-dt-content-rid-14232401_1/courses/BIO1101.90155.201714/BIO1101.90155.201714_ImportedContent_20160930044714/CourseRoot/html/lab006s002.html

https://nuonline.neu.edu/bbcswebdav/pid-9451341-dt-content-rid-14232402_1/courses/BIO1101.90155.201714/BIO1101.90155.201714_ImportedContent_20160930044714/CourseRoot/html/lab006s003.html

 

 

 

 

 
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