Download Chapter 5: Membrane structure and Transport Directions: In your

Chapter 5: Membrane structure and Transport
Directions: In your groups, you may use the notes/outlines you have prepared for your chapter 4 and 5 reading to
answer these questions. All students must work together and maintain their own copy, but one will be collected for the
group. Any student without their notes will complete this assignment on their own without the benefit of their group.
Structure and Function of the Cell membrane and Cell wall:
1. Obtain the pages to build your model of a membrane. This will be collected
2. Describe each of the components of your model as well as their function as a part of the membrane.
3. This is a simplified model, of course. What additional components make up the membrane. List them below
and describe the function of each.
4. How does the structure of the cell wall differ from that of the cell membrane?
5. How do materials pass through the cell wall? Is movement through the cell wall as selective as movement
through the membrane? Explain
6. What are the criteria that will determine if a molecule will pass through the phospholipid bilayer (meaning
without the help of proteins)?
7. Identify the mode of transport used to move each of the following
A.
B.
C.
D.
E.
F.
G.
Individual molecules of Water in a concentration dependent manner
CO2, O2 and other small/non-polar substances
Ions moving with the concentration gradient (high  low)
Large/Polar molecules like glucose or amino acids
A bacterial cell, chunk of food, dead cells
Bulk transport of liquids independent of concentration
Ions moving against the concentration gradient (low  high)
8. Write the word “Energy” next to any active processes above.
9. Write the word “protein” next to any processes that require either channel or carrier proteins
10. A dialysis tubing balloon is filled with sucrose solution of an unknown concentration. The tubing is permeable
to water but NOT sucrose.
a. What will happen to the balloon if it is placed in a beaker filled with a sucrose solution that is a HIGHER
concentration than inside the balloon?
b. What will happen to the balloon if it is placed in a beaker filled with a sucrose solution that is a LOWER
concentration than inside the balloon?
c. What will happen to the balloon if it is placed in a beaker filled with a sucrose solution that is THE SAME
concentration as inside the balloon?
d. What process is being observed above?
11. A tank is set up with a barrier down the middle. The right side is filled with 0.25M salt solution and 0.5M glucose
solution. The left side is filled with 0.65M salt solution and .8M glucose. After the tank is set up, the barrier is
removed completely allowing the molecules to do their thing.
a. In which direction will each of the molecules move?
b. What will be the equilibrium concentration for each solution?
-
12. A U-tube is set up with a semi-permeable membrane separating its left and right sides. The membrane is
permeable to glucose (and water obviously) but not to starch.
The right side is filled with 0.6 M glucose solution and 0.3 M starch solution.
The left side is filled with 0.2M glucose solution and .5 M starch solution.
Both of the above solutions are made with water
a.
Draw the U-tube set up below and label the contents of each side.
b. In what direction will each molecule move as it attempts to equilibrate the two sides?
13. What two forces determine the direction of water movement in a plant cell?
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14. A plant cell is placed in a beaker filled with solution.
The pressure potential in the cell is 0.7 and the solute potential is -0.7M.
The pressure potential in the beaker is 0 and the solute potential is -0.9.
a. What is the overall water potential of the plant cell?
b. What is the overall water potential of the beaker?
c. In what direction will the water move?
d. At equilibrium, what should be true about the overall water potential for both the plant cell and the
beaker?
e. At equilibrium, will the individual pressure and solute potential necessarily be equal between the plant
cell and beaker? Explain.
f.
If we add solute to the beaker, what effect will it have on each of the following?
i. The beaker’s solute potential?
ii. The beaker’s pressure potential?
iii. The beaker’s overall water potential?
15. Explain how plants as a whole maintain a constant flow of water from roots to the leaves? Include specific
processes as well as a discussion of water potential.