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Question: cell membranes lab report diffusion compare the following terms solvent...

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           Cell Membranes Lab Report

  1. Diffusion

  1. Compare the following terms: solvent, solute, and solution.

  1. Go to Lab, Section I, Exercise 1 to explore the factors influencing the rate of diffusion and complete the following:

  1. Predict how molecular mass and temperature may affect the outcome of this experiment.   

  1. Record the data from information in the Lab in the table below.

Time

(min)

Diameter (mm)

5°C MB

5°C PP

23°C MB  

23°C PP

0

15

30

45

  1. Construct a line graph of the data from the table above. Your graph should include labeled axes, units, and a legend indicating which treatment is presented. Sign, date and prepare an image of your graph and include it with this lab report.     
  1. Osmosis

  1. Go to Lab, Section II, Exercise 2 to view a demonstration of osmosis and answer the following questions:

  1. Describe the net movement of water in osmometer 1.
  1. How is the movement of water molecules related to the concentration gradient of the solution?

  1. Go to Lab, Section II, Exercise 3 to observe the effect of solute concentration on the rate of osmosis. Answer the following questions:

  1. Was the net movement of water in bags 1 to 4 into or out of the bags?
  1. Explain the results from bags 4 and 5.   
  1. Selective Permeability of Membranes

  1. Go to Lab, Section III, Exercise 4 to learn about the importance of selectively permeable membranes, then complete the table and answer the following questions:

Contents of Beaker

0 Min

30 Min

Starch

Chloride ion

  1. Which substances diffused through the dialysis membrane?

  1. How does dialysis tubing model the selective permeability of a plasma membrane?
  1. Tonicity

  1. Go to Lab, Section IV, Exercise 5 and 6 to observe plasmolysis in Elodea cells and tonicity in red blood cells. Summarize the concept of tonicity using blood and Elodea cells as examples. Your description should incorporate these terms: turgid, plasmolysis, hemolysis, and crenation.

Cells

Isotonic Solution

Hypertonic Solution

Hypotonic Solution

Elodea

RBC

  1. Based on your previous work, reproduce the table below and draw an illustration of a single cell in each box. Include arrows to show the direction of water flow relative to each cell and dots to symbolize solutes. Sign, date and prepare an image of your drawing and include it with this lab report.

Cells

Isotonic Solution

Hypertonic Solution

Hypotonic Solution

Elodea

RBC

Summary Questions

  1. Compare diffusion and osmosis. Give an example of each.   

2. In which direction will osmosis occur if a 15% sugar solution is separated from a 25% sugar solution by a selectively permeable membrane?   

3. Why did osmosis, but not diffusion of sucrose molecules, occur across the dialysis membrane containing 20% sucrose solution?   

4. You are having a party and the celery is limp. What might you do to make the celery crisp (turgid) again? What will occur in the cells?   

5. A small amount of fertilizer (mineral salts) will stimulate plant growth, but over fertilization can kill plants? Why?   

6. Michael adds sugar to his coffee. Explain what in this drink is the solvent, solute, and solution.   

7. You add a cube of sugar to your drink. How could you speed up the diffusion of sugar molecules without stirring?   

8. How is dynamic equilibrium established within a solution?   

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