CELL MEMBRANE AND TRANSPORT HW
DR WEINER
AP BIOLOGY
Multiple choice questions (2 pts)
Questions 1 to 3 refer to the following figure in which a dialysis bag is filled with a solution of glucose
and starch is placed in a beaker of distilled water and IKI. After 1h the solution inside the dialysis bag
has turned black while the solution in the beaker is still brown.
Solution of 3% starch and 3% glucose
Distilled water with IKI
1. Which of the following is an ccurate conclusion that can be made only from the observed
results?
a. The dialysis tubing weighs less
b. Glucose has not diffused across the dialysis tubing membrane
c. The dialysis tubing is selectively permeable
d. A net movement of water into the beaker has occurred.
2. The change in solution color to black is a positive indicator by IKI for the presence of starch.
Based only on the results, which of the following conclusions can be made?
a. The dialysis tubing is permeable to starch
b. The pores of the dialysis tubing are larger than IKI
c. The dialysis tubing is not permeable to glucose
d. A net movement of water into the dialysis tubing has occurred
3. Which of the following best describes the system after it reaches equilibrium?
a. Water will have a net movement into the dialysis bag
b. The osmotic pressure inside the dialysis tubing will be the Same as the osmotic pressure
in the surrounding solution
c. IKI will have a net movement into the dialysis bag
d. Glucose will have a net movement out of the dialysis bag
4. A saturated solution of starch is placed in a dialysis bag such that water can pass through but
starch cannot. The bag is then placed into a beaker of distilled water. All of the following are
expected to occur EXCEPT
a. There will be a net movement of water from a hypotonic region to hypertonic region
b. There will be a net movement of solute from a hypertonic region to a hypotonic region
c. The dialysis bag and its contents will gain weight
d. No starch will be detected outside the bag
The following questions refer to a section of freshly cut potato that is put into a beaker of distilled water.
Use the following to answer the questions
a. Is greater than 0
b. Is equal to 0
c. Is less than 0
d. Is the same in the distilled water as it is in the potato cell
5. The value of Ψ for the distilled water before the potato is added
6. The value of Ψs inside the potato cell before it is added to the water
7. The value of Ψp inside the potato cell before it is added to the water
Use the following figure to answer the questions
8. In beaker B, what is the water potential of the distilled water in the beaker and of the beat core?
a. Ψ of the beaker is 0 and Ψ of the beet core is 0
b. Ψ of the beaker is 0 and Ψ of the beet ore is -0.2
c. Ψ of the beaker is 0 and Ψ of the beet core = 0.2
d. Ψ of the beaker cannot be calculated and Ψ of the beet is -0.2
9. Which of the following is true for the figure?
a. The beet core in beaker A is at equilibrium with the surroundings
b. The beet core in beaker B will lose water to the surrounding environment
c. The beet core in beaker B would be more turgid than the beet core in beaker A
d. The beet core in beaker A is likely to gain so much water that it will rupture
Questions 10 and 11 refer to an experiment in which there is an initial setup of a U-tube with its 2 sides
separated by a semipermeable membrane that permits the passage of water and NaCl but not glucose.
The U-tube is filled on one side with 0.4M glucose and 0.5M NaCl and on the other side with 0.8M
glucose and 0.4M NaCl
10. When the U-tube was set up at time = 0 in the experiment, which of the following was true?
a. The solution on side A was hypertonic to the solution on side B
b. The solution on side B was hypertonic to the solution on side A
c. The two solutions were isotonic
d. Active transport moved glucose from side A to side B
11. After the experiment ran for 1 h, the expected fluid levels in the U-tube would be
a. Higher on side A than side B
b. Higher on side B than side A
c. Even on both sides
d. Equal but the solutes would be reversed
12. Which of the following is a way for membranes of winter wheat to remain fluid when it is
extremely cold?
a. Increase the number of unsaturated fatty acids in the membrane
b. Increase the amount of cholesterol in the membrane
c. Decrease the number of hydrophobic proteins in the membrane
d. Both a and b are correct
13. In a paramecium, cell surface integral membrane proteins are synthesized
a. In the cytoplasm by free ribosomes
b. By ribosomes in the nucleus
c. By ribosomes bound to the RER
d. By ribosomes bound to the inner surface of the plasma membrane
14. A patient has a serious accident and lost a lot of blood. In an attempt to replenish body fluids,
distilled water, equal to the volume of blood lost, is transferred directly into one of his veins.
What will be the most probable result of this transfusion?
a. It will have no unfavorable effect as long as the distilled water is free of bacteria and
viruses
b. The patient’s red blood cells will shrivel up because the body fluid has become hypotonic
to the cells
c. The patient’s red blood cells will swell because the body fluid has become hypotonic to
the cells
d. The patient’s red blood cells will shrivel because the body fluid has become hypertonic to
the cells
15. You are working on a team that is designing a new drug. In order for the drug to work, it must
enter the cytoplasm of specific target cells. Which of the following would be a factor that
determines whether the molecule selectively enters the target cell?
a. Blood or tissue type of the patient
b. Hydrophobicity of the drug molecule
c. Similarity of the drug molecule t other molecules transported by the target cell
d. Lipid composition of the target cell’s plasma membrane
Five dialysis bags were filled with various concentrations of sucrose. The tubing is impermeable to
sucrose. The bags were then placed in a beaker of 0.6M sucrose. The bags were then massed at 10
minute intervals and the mass of each bag was graphed
16. Which of the lines in the graph represents the bag that contained a solution isotonic to the 0.6M
solution at the beginning of the experiment?
a. A
b. B
c. C
d. D
e. E
17. Which of the lines in the graph represents the bag with the highest initial concentration of
sucrose?
a. A
b. B
c. C
d. D
e. E
18. Which of the lines in the graph represents the bag(s) that contain a solution that is hypertonic at
50 minutes?
a. A and B
b. B
c. C
d. D
19. A cell engulfs an organism, enclosing it in a vesicle. The organism is partially digested in that
vesicle, and the waste is excreted from the cell. The cell is using
a.
b.
c.
d.
endocytosis followed by pinocytosis
pinocytosis followed by exocytosis
endocytosis followed by phagocytosis
phagocytosis followed by exocytosis
20. Exocytosis is a process by which a cell
a. passes substances out of the cell in vesicles
b. passes substances out of the cell by osmosis
c. release substances directly out of the cell through a pore
d. release substances out of the cell through a pit
21. Newer, softer portions of plants hold their shape largely by
a. cell wall thickness
b. root pressure
c. turgor pressure
d. wood fibers
22. A plant cell placed in a hypotonic solution will
a. plasmolyze
b. shrivel
c. become flaccid
d. become turgid
Question 17-20:
Wet mounts of three living samples of elodea cells are prepared for viewing under the light microscope.
Each slide is mounted with a different solution and viewed after 5 minutes.
Sample A = elodea + 5 drops of 10% NaCl
Sample B = elodea + 5 drops of isotonic saline
Sample C = elodea + 5 drops of distilled water
23. The cells in sample A would
a. Exhibit turgor pressure
b. Undergo lysis
c. Swell and burst
d. Exhibit plasmolysis
e. Remain unchanged
24. The results of the experiment illustrate which of the following processes?
a. Hydrolysis
b. Dehydration
c. Active transport
d. Polymerization
e. Osmosis
25. Which cell structure would be visible in sample A that was not visible prior to exposure to the
10% NaCl?
a. Nucleus
b. Mitochondria
c. Golgi apparatus
d. Plasma membrane
e. Chloroplasts
26. Which of the following statements about the experiment is correct?
a. The movement of salt is the dependent variable
b. The elodea cells in sample C are in a hypotonic solution
c. There is no passage of water in either direction in sample B
d. NaCl is a toxin that would destroy any cell, no mater the concentration
e. You cannot predict with any certainty what would happen to these cells; they are living
organisms.
27. All of the following about plasma membranes structure and function are true EXCEPT
a. All plasma membranes have the identical composition and structure
b. Diffusion of gases across the membrane requires that the membranes be moist
c. Facilitated diffusion is an example of passive transport
d. Proteins serve as membrane channels
e. Plasma membranes contain receptors that are specific for the molecules they uptake
Question 22-24:
Five beakers are used in an experiment about osmosis. Each beaker contains 50 ml of a sucrose solution
of varying concentration: 0.2M, 0.4M, 0.6M, 0.8M, 1.0M. Pieces of fresh potatoes (each 10.0g in mass)
are cut up, weighed, and placed into the beakers. After 12 hours, the potatoes are carefully removed
from each beaker and weighed again. See the data in the table below.
beaker
Concentration of
Mass of potato at time
Mass of potato after 12
sucrose
zero
hours
1
0.2M
10.0g
8.2g
2
0.4M
10.0g
9.4g
3
0.6M
10.0g
10.8g
4
0.8M
10.0g
11.5g
5
1.0M
10.0g
13.6g
28. In this experiment
a. Water flowed into the potato only
b. Water flowed out of the potato only
c. Sucrose flowed into the potato only
d. Sucrose flowed both into and out of the potato
e. Water flowed both into and out of the potato
29. Given the results of this experiment, what is the molarity (concentration) within the potato cells?
a. Less than 0.2M
b. Less than 0.4M but greater than 0.2M
c. Less than 0.6M but greater than 0.4M
d. Less than 0.8M but greater than 0.6M
e. Greater than 0.8M
30. the results of this experiment give support to the theory that
a. water diffuses down a gradient
b. water can be actively transported against a gradient
c. solutes will diffuse from high to low concentration
d. living cells can respond in different ways to the same conditions
e. potato cells respond differently from other living cells
Essay Questions (10 pts)
1. How would increasing the number of unsaturated fatty acids in the cell membrane affect the fluidity
of the membrane? Why might this be important?
2. Glucose moves across the membranes of red blood cells via facilitated diffusion. A scientist studying
glucose transport into red blood cells generated the following graph. Explain why she got these
results.
rate of transport
500
400
300
200
100
0
0
10
20
30
40
50
extracellular glucose concentration (m M)
60
70