BIO201 Lab 4
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Lab 4 Diffusion and Osmosis
BIO201L
Student Name:
Kadesha Alawar-Taylor.
Access Code (located on the lid of your lab kit):
AC-920H4U.
Lab Report Format Expectations
Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre-
lab Questions
1.
Define the following terms.
a.
hypertonic solution:
Hypertonic solution is one with a higher solute concentration than the solute concentration on the opposite side of the permeable embrane.
b.
hypotonic solution:
A solution with a lower solute concentration than the solute concentration on the opposite side of the permeable membrane.
c.
isotonic solution:
a solution with equal solute and concentration of both sides.
2.
Define osmotic pressure.
Osmotic pressue is the force required to prevents osmosis or lyse of cells. It is the pressure in cels due to the concentration levels of solutes and solvents.
3.
Explain what would happen to a cell placed in a hypertonic solution.
Because the concentration os olutes is greater than the concentration of solvents in the cell, if a cell was placed into a hypertonic soluton, the water from nside the cell would diffuse to the outside and cause the cell to shrink.
Lab 4 Diffusion and Osmosis
BIO201L
EXPERIMENT 1: DIFFUSION THROUGH A LIQUID
Introduction Questions
1.
State the molecular weight of the blue dye in grams per mole.
Click here to enter text.
2.
State the molecular weight of the red dye in grams per mole. Click here to enter text.
3.
Why does this experiment require two dyes of different molecular weights? Answer this question, ensuring you explain the purpose of these two dyes in relation to the experiment. Click here to enter text.
Lab 4 Diffusion and Osmosis
BIO201L
Data and Observations
Record the diameters you observed for both dyes in the table below. Table 1: Rate of Diffusion in Corn Syrup
Time (sec)
Blue Dye
Red Dye
10
Input
Input
20
Input
Input
30
Input
Input
40
Input
Input
50
Input
Input
60
Input
Input
70
Input
Input
80
Input
Input
90
Input
Input
100
Input
Input
110
Input
Input
120
Input
Input
Calculate the speed of diffusion and present this, along with the required data, for both dyes below in Table 2. To calculate the hourly diffusion rate, multiply the total distance diffused by 30
. Table 2: Speed of Diffusion of Different Molecular Weight Dyes
Structure
Molecular Weight
Total Distance
Traveled (mm)
Speed of Diffusion
(mm/hr)*
Blue Dye
Input
Input
Input
Red Dye
Input
Input
Input
Results and Discussion
1.
Examine the plot below. How well does it match the data you took in Table 1?
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Lab 4 Diffusion and Osmosis
BIO201L
Click here to enter text.
2.
Which dye diffused the fastest?
Click here to enter text.
3.
How does the rate of diffusion correspond with the molecular weight of the dye?
Click here to enter text.
4.
Does the rate of diffusion change over time? Why or why not? Click here to enter text.
EXPERIMENT 2: DIFFUSION - CONCENTRATION GRADIENTS AND MEMBRANE PERMEABILITY
Introduction Questions
1.
What is the purpose of Step 5 in this experiment? Click here to enter text.
2.
Why is it necessary to have positive and negative controls in this experiment?
Click here to enter text.
Lab 4 Diffusion and Osmosis
BIO201L
3.
What is the importance of Step 16 in the procedure? Click here to enter text.
Data and Observations
Record your observations of Steps 5 and 6 below. These values will be used to interpret your results. 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
Input
Input
IKI
Input
Input
n/a
n/a
Record your observations from Steps 13 through 16 below. Table 4: Diffusion of Starch and Glucose Over Time
Indicator
Dialysis Bag After 1 Hour
Beaker Water After 1 Hour
Glucose Test Strip
Input
Input
IKI
Input
Input
Lab 4 Diffusion and Osmosis
BIO201L
Results and Discussion
1.
Which substance(s) crossed the dialysis membrane? Support your response with data-based evidence. Click here to enter text.
2.
Which molecules remained inside of the dialysis bag? Click here to enter text.
3.
Did all of the molecules diffuse out of the bag into the beaker? Why or why not? Click here to enter text.
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Lab 4 Diffusion and Osmosis
BIO201L
EXPERIMENT 3: OSMOSIS - DIRECTION AND CONCENTRATION GRADIENTS
Introduction Questions
1.
Before conducting the experiment, read through the steps to gain a full understanding of the experimental process involved. Then provide the hypothesis from Step 16 here. Click here to enter text.
2.
Osmosis is how excess salts that accumulate in cells are transferred to the blood stream so they can be removed from the body. Explain how this process works in terms of tonicity. Click here to enter text.
3.
How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.
Click here to enter text.
Data and Observations
Record the observed volumes from Steps 14 and 19 below. Also calculate the net displacement. Table 6: Sucrose Concentration vs. Tubing Permeability
Band Color
Sucrose %
Initial Volume (mL)
Final Volume (mL)
Net Displacement (mL)
Yellow
Input
Input
Input
Input
Red
Input
Input
Input
Input
Blue
Input
Input
Input
Input
Green
Input
Input
Input
Input
Lab 4 Diffusion and Osmosis
BIO201L
Results and Discussion
1.
For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution it was placed in. Click here to enter text.
2.
Which tubing increased the most in volume? Why?
Click here to enter text.
3.
What does this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?
Click here to enter text.
4.
What would happen if the tubing with the yellow band was placed in a beaker of distilled water?
Click here to enter text.
5.
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. Click here to enter text.
Lab 4 Diffusion and Osmosis
BIO201L
EXPERIMENT 4: OSMOSIS - TONICITY AND THE PLANT CELL
Introduction Questions
1.
Can all cells generate osmotic pressure? If not, which ones are able to do this? Click here to enter text.
2.
What specialized structure do some cells utilize to generate osmotic pressure? Click here to enter text.
Data and Observations
Record your observations from the experiment in the table below. Also calculate the net displacement.
Table 7: Water Displacement per Potato Sample
Potato
Potato Type and
Observations
Sample
Initial
Displacement
(mL)
Final
Displacement
(mL)
Net
Displacement
(mL)
1
Input
1A
Input
Input
Input
1
Input
1B
Input
Input
Input
2
Input
2A
Input
Input
Input
2
Input
2B
Input
Input
Input
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Lab 4 Diffusion and Osmosis
BIO201L
Results and Discussion
1.
How did the physical characteristics of the potato vary before and after the experiment? Did it vary by potato type? Click here to enter text.
2.
What does the net change in the potato sample indicate?
Click here to enter text.
3.
Different types of potatoes have varying natural sugar concentrations. Explain how this may influence the water potential of each type of potato. Click here to enter text.
4.
Based on the data from this experiment, hypothesize which potato has the highest natural sugar
concentration. Explain your reasoning. Click here to enter text.
5.
Did water flow in or out of the plant cells (potato cells) in each of the samples examined? How do you know this? Click here to enter text.
6.
Would this experiment work with other plant cells? What about with animal cells? Why or why not? Click here to enter text.
7.
From what you know of tonicity, what can you say about the plant cells and the solutions in the test tubes? Click here to enter text.
8.
What do your results show about the concentration of the cytoplasm in the potato cells at the start of the experiment? Click here to enter text.
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