065 0 Akron Biology Hollingsworth Lab3 R4

8/12/2019 065 0 Akron Biology Hollingsworth Lab3 R4

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Biology

Diffusion & Osmosis

3P R E L A B

Sugarmolecule

Lump ofsugar

What are we going to do today? Diffusion Osmosis Why are these important to Biology? Why do I need to know about these?

DiffusionHigh concentration to low concentration

Tink about the diffusion of... Perfume Gases/Smells Sugar in iced tea A drop of food coloring in water

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Diffusion is passive- doesn't require any energy.For example:

Perfume in a room Where does the smell go?

OsmosisSemi-permeable Membrane - allows certain

molecules to diffuse through it

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Semi-permeable membrane - Allowing passage ofcertain, especially small, molecules or ions but actingas a barrier to others.

Analogy a semi permeable membrane is like ascreen door at your house. It allows for the passage ofair, but doesnt allow bigger things such as ies,pollen, dogs, or humans to pass through.

Lab 3 : Diffusion & Osmosis

Biology3-2

Semi Permeable Membrane

High Solute Low Solute


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Water (osmosis) balance in cells e outside cell membrane of a red blood cell is a

semi-permeable membrane

Vocabulary to know Hypotonic- distilled water (what would happen

to your body if you drank too much water?)

Hypertonic- salt water (what would happen toyour body if you ate too much salt?)

Isotonic- water enters and leaves at the same rate(equilibrium, balance, homeostasis)

Vocabulary to know Hypo= below/less

tonic= Solutes or particles

This means hypotonicsolutions have lesssolutesin them than the cell has inside itself (oppositeof hypertonic).

Isotonicsolution:H

2O enters and

exits the cell

Hypertonicsolution:H

2O exits the cell

Hypotonicsolution:H

2O enters the cell

Lab 3 : Diffusion & Osmosi

Biology 3-3


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Could you put a saltwater fish like aclownfish in a freshwater stream witha salmon? What do you think wouldhappen? What about the reverse?

odays Lab: Simulated Kidney A kidney is a complex organ that uses osmosis

and diusion in many ways.

To illustrate these properties, we will create asimplied modelof kidney function.

A modelis a simplied explanation of a complexsystem, and is used to understand the importantfactors of that system.

What would happen to you if youwere lost on a boat in the ocean?How could you survive?


Biology3-4


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Why are we going to talk about Kidneys? Metabolism, Homeostasis

All the blood in the bodymust pass throughthe kidneys.

Kidneys lter all waste out of your body(urea, ammonia, salts, drugs, water, andother toxic substances)

Cells of tissue

Tissue (interstitial) uid

Venule

Lymphatic vessel

Lymphatic capillary

Arteriole

Flow of lymphatic uid

Capillaries

Red blood cell

Wall of capillary

Respiring cells

Z

Y

X

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What is Dialysis ubing? Dialysis Tubing is a type of semi or partially

permeable membrane tubing made fromregenerated celluose or cellophane. It is usedfor diusion, or more accurately osmosis.It allows the passage of small molecules butnot larger ones.

Biological Processes Metabolism e chemical processes occurring

within a living cell or organism that are necessaryfor the maintenance of life.

Cells (Blood Cells, Animal Cells)

Molecules (Waste Molecules,Salt Molecules, Sugar Molecules)

Homeostasis e ability or tendency of an

organism or cell to maintain internal equilibrium,

or stability, by adjusting its physiological processes.

ings that aect diusion -

1. Agitation- stirring, shaking 2. emperature- as heat increases, diusionincreases

3. Concentration- diusion happens from anarea of higher concentration, and goes towardslower concentration.


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Kidney Dialysis Simulation3 L A B

Biology 3-7

A.

H2O

H2O

Aer completing this activity, students will be able to Dene the terms diusion, osmosis, hypotonic, hypertonic, isotonic. Construct a model to simulate the action of a kidney. Relate changes in color, turgor, and salt concentration to evidence of osmosis. Evaluate the function of the kidney as an evolutionary adaptation to life on land.

What is the difference between diffusion and osmosis? Diusion is the transport ornatural dri of moleculestraveling from an area of higher concentration to an area oflower concentration. Diusion does not require outside energy (passive) from the cell.Osmosis is the movement of watermolecules across a selectively permeable barrierfrom a place where they are in high concentration to a place where they are in lowconcentration. Both diusion and osmosis do not require energy, so they areconsidered passive transport.

Figures A and D isotonic- same amount of water is going into andcoming out of the cell.

Figure B hypotonic- water entersthe cell due to a high concentrationof dissolved molecules (like salt) on the insideof the cell.

Figure C hypertonic- water leavesthe cell due to a high concentrationof dissolved molecules on the outsideof the cell.

Learning Objectives

Background Information

Water molecule

Dissolved molecule

B.

H2O

H2O

H2O

C.

H2O

D.

H2O

H2O

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Biology3-8

Key Vocabulary

cellulose excreted metabolismconcentration isotonic osmosisdialysis hypertonic selectively permeable membranediusion hypotonic solutes

distilled water membrane turgor pressure

5 ml unltered simulated bloodone pre-cut strip dialysis tubing (made from cellulose)2 dialysis tubing clamps250 ml beaker4 salt test stripspipette

disposable glovesstopwatch

Although we are using simulated blood in this lab, which is completely safe and non-toxic,you still do not want to spill the blood on your skin. e simulated blood may cause stains.

1. Cover your work station with paper towels, to make cleanup easier.2. Fill a 250 ml beaker with 200 ml of distilled water. Dip one of the test strips into the

water and determine the initial presence of salt in the water. Remove the strip fromthe water and wait 30 seconds. A color change of the test pad is an indicator of apositive result. Record a positive or negative test result using the key on the test stripbottle and note any color change in Table 1 in the Data section.

3. With each test strip you use, make sure to label the strip! When you are looking at yourstrips for the results, you must be able to distinguish between them.

4. Test the simulated blood for the presence of salt by following the same procedure aslisted in Step 1. Record a positive or negative result in Table 1.

5. Obtain a piece of dialysis tubing from the beaker of water. Using a clamp, secureone end of the tubing. Open the other end by rubbing the tubing between your ngers.Pipette approximately 5 ml of the simulated blood into the tubing and clamp theopen end of the tubing to form a bag. is bag represents the blood vessels that enterthe kidney.

6. Rinse o the outside of the dialysis bag under running water to remove any excessblood and place the bag in the beaker. Record the initial color of the solution in thedialysis bag and of the water in the cup in Table 1.

Materials

Safety

Procedure


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Biology 3-9

Procedures (continued)

7. Aer 15-20 minutes, remove the bag from the cup. Record the color of the solution

in the bag and of the water in the beaker in Table 1.

8. Determine the presence of salt in the water in the beaker, as in Step 1. Record the

result in Table 1.

9. Make a small slit in the upper portion of the dialysis bag. Insert a salt test strip

into the slit and test the simulated blood. Record this result in Table 1.

10. Dispose of all your materials in the laboratory waste receptacle.

While you are waiting for your cell to diuse, lets talk about a real world example of

diusion. For an organism to survive, it needs to get rid of metabolic waste materials,

as well as maintain proper concentrations of various necessary materials. For example,

human food consists of carbohydrates, fats, proteins, various salts, and water. As these

materials are metabolized(used by the body for energy), certain waste products areproduced, such as carbon dioxide, water, urea and related nitrogenous compounds, salt,

and various minerals. If these waste materials remain in the body, they quickly upset

the bodys equilibrium (homeostasis), so they must be excreted(expelled) rapidly and

eciently.

What would happen if you couldnt get rid of the toxic wastes from your body?

e kidneysare very important organs within the human body because they are essential

to maintaining homeostasis. Humans have two bean-shaped kidneys that are found at

the back of the abdominal cavity, one found on each side of the spine. Each kidney is

approximately the size of a persons st. All of the blood in the bodymust pass through

the kidneys. e large amount of blood that is passed through the kidneys allows them to

do the following:

Assist in the regulation of blood pressure.

Stimulate red blood cell production.

Maintain calcium levels in the body.

Regulate the composition of the blood by keeping the pH, concentration of variousions, and the volume of water constant. e kidneys lter wastes (urea, ammonia,

salts, drugs, water, and other toxic substances) from the bloodstream in order to keepthe blood clean and chemically balanced.

Maintain homeostasis in the cells.

Why do we study a model of a kidney, and not the actual kidney, in this lab?


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Biology3-10

Ureter

Medulla

Cortex

Figure 1

Renal ArteryRenal Vein

Renal Pelvis

e anatomy of the kidneys provides agreater understanding of the major role theyhave in maintaining homeostasis within apersons body (Figure 1).

Te kidneys are able to filter approximately180 liters offiltrateper day; however,they only excrete 1 to 1.5 liters of urine,conserving the amount of water loss andgreatly concentrating the salts and otherwastes in the urine.

e function that the kidneys perform is sovital to a humans survival that total kidneyfailure can cause a person to die in a very

short time. e two most common causesof kidney disease are: High blood pressurecan damage the small blood vessels in the kidney, not allowing

for ltration of poisons from the bloodstream. Diabeteskeeps a persons body from using sugar as it should. e sugar then stays in

the bloodstream instead of breaking down. In turn, it acts like a poison that candamage the kidneys.

Kidney disease cannot be cured. However, it may be possible to make the kidneys lastlonger if kidney disease is detected in the early stages. Certain precautionary measures thatcan be taken in these early stages include regularly checking blood pressure, avoiding pain

pills that may make kidney disease worse, carefully watching the diet by limiting proteins,salt, and cholesterol, and watching blood sugar levels very closely.

Fortunately, medical technology has developed a machine, known as dialysis, that canserve as an articial kidney, ltering out wastes and replenishing the body with clean blood. With only a few hours of dialysis a week, a person may live for years withoutfunctioning kidneys while they wait for a suitable kidney transplant to become available.

Procedures (continued)


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Kidney Dialysis Simulation Lab3R E P O R T S H E E TNAME DATE

TA SECTION

Biology 3-11

Results

Table 1:

Reading

Presence of Salt (+ or -) Color

Dialysis Bag Beaker Dialysis Bag Beaker

Initial

Final

1. Summarize how the model used in the lab demonstrates kidney function.

2. How is the kidney like a waste water treatment plant?

3. Aside from ltering the blood, name another function of the kidneys.

Questions


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Biology3-12

4. Why would certain substances in the urine (e.g., protein, sugar, blood) be animportant diagnostic tool for the medical community?

5. How do you slow down or speed up diusion?

6. Why do you have to rinse the blood o of the cell before you put it in the beaker?

7. Describe the concentration of salt in the beaker at the beginning of the experiment.What about the blood cell?

8. Describe the concentration of salt in the beaker at the end of the experiment.What about the blood cell?

9. What are some of the dierences in structure and composition between a humanblood cell and the dialysis tubing? How does this aect what is able to pass throughthese two items?

10. Based on your cell model, would a kidney with more toxins diuse faster or slowerthan a kidney with less toxins?

Questions (continued)

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065 0 Akron Biology Hollingsworth Lab3 R4