Ch. 5
The Working Cell: Membrane Function
Name ___________________________
Date ___________________________
Period ____________
Cell Biology
1. The fundamental life processes of plants and animals depend on a variety of chemical reactions
that occur in specialized areas of the organism's cells. As a basis for understanding this concept:
a. Students know cells are enclosed within semipermeable membranes that regulate their
interaction with their surroundings.
Read the appropriate section in the textbook before answering the following questions. You must put all
answers and definitions in your own words for full credit.
Membrane Function
1. Label the structures found in the plasma membrane of animal cells.
e.
d.
c.
b.
a.
2. Explain why the plasma membrane exhibits selective permeability. Include the definition of selective
permeability.
3. Describe a phospholipid bilayer: (include a sketch labeling important features)
J. Haut. (2007). Pre-AP Biology.
4. Describe the functions of the different proteins that are found in the plasma membrane.
a.
b.
c.
d.
e.
f.
Passive Transport: Diffusion across Membranes
5. diffusion:
6. Give your own example of diffusion.
7. concentration gradient:
8. equilibrium:
9. passive transport:
10. When substances are able to pass through a membrane, the membrane is said to be
________________ to it.
11. facilitated diffusion:
12. Which kind of molecules must use facilitated diffusion to cross the membrane?
J. Haut. (2007). Pre-AP Biology.
13. Look at the cells below. The ‘X’ indicates solute molecules. Assume that the cell is permeable to the
solute. Draw arrows on the figure in the before column to indicate the direction of diffusion. Then
draw what the cell would look like once equilibrium is reached in the after column.
Before Equilibrium is reached
After Equilibrium is reached
X
X
X
X
X
X
X
X X
X X
X X
X X X
X X
X X X
X
X
X
X
X
a.
X
X
X
X
X
X
X
X
X
X
X
X
X X X
X X
X
b.
14. hypertonic:
15. hypotonic:
16. isotonic:
17. In the diagram above, 13a, the cell solution is _____________________ relative to the environment.
18. In the diagram above, 13b, the cell solution is _____________________ relative to the environment.
19. osmosis:
J. Haut. (2007). Pre-AP Biology.
20. Directions of Osmosis. To describe the solutions use the terms hypertonic, hypotonic or isotonic.
Environment
Cell
Water will
Conditions
solution is…
solution is…
move…
a. If solute concentration in the
environment is lower than in
the cell
b. If solute concentration in the
environment is higher than
in the cell
c. If solute concentration in the
environment is equal to that
in the cell
21. osmoregulation:
22. Describe what happens to animal and plant cells when they are put into a hypotonic solution such as
distilled water? Include a diagram for each.
23. Describe what happens to animal and plant cells when they are put into a hypertonic solution such as
seawater (high salt concentration)? Include a diagram for each.
24. plasmolysis:
25. Describe how a Paramecium’s contractile vacuole is able to maintain homeostasis.
J. Haut. (2007). Pre-AP Biology.
Osmosis is an important process that has many effects on living things. Test your understanding of
osmosis by predicting in each of the following cases whether water will enter the cell (IN) or leave the
cell (OUT), or whether there will be no net movement of water (NONE). Assume that the plasma
membrane is permeable to water but not solutes. Put your answer in the blank after the statement.
26. Cell is exposed to hypertonic solution. ________
27. Cell is placed in salt solution whose concentration is greater than cell contents. ________
28. Due to disease, solute concentration of body fluid outside cell is less than solute concentration of
cells________
29. Cell is in isotonic solution________
30. Single-celled organism is placed in drop of pure water for examination under microscope. ________
31. Cell is immersed in solution of sucrose and glucose whose individual concentrations are less than
concentration of solutes in cytoplasm, but whose combined concentration is greater than
concentration of solutes in cytoplasm. ________
32. Solute concentration of cell is greater than solute concentration of surrounding fluid. ________
33. Cell is exposed to hypotonic solution. ________
34. Concentration of solutes in cytoplasm is equal to solute concentration of extracellular fluid. ________
35. Cytoplasm more dilute than surrounding solution. ________
36. If you were stranded in the ocean on a life raft and really thirsty, would you drink the seawater around
you? Why/why not? Think about what you just learned about water balance in cells.
37. active transport:
38. Diagram and explain how an active transport system is involved with the passage of 2 different
solutes across a membrane, in opposite directions (refer to notes for further assistance).
39. During exercise, potassium ions build up in the fluid surrounding muscle cells. Which cell-membrane
protein helps muscle cells counteract this tendency? Explain your answer.
J. Haut. (2007). Pre-AP Biology.
40. Some molecules, such as food particles and waste materials, are too large to pass through the cell
membrane. However, the processes called ____________________ and ____________________
enable these large molecules to enter and leave the cell without passing through the cell
membrane.
41. endocytosis:
42. exocytosis:
43. pinocytosis:
44. phagocytosis:
45. receptor-mediated endocytosis:
Review diffusion and the function of cell membranes by matching each of the phrases on the right with
the appropriate function from the list on the left. Some questions will require more than one answer.
A. diffusion
B. active transport
C. osmosis
D. phagocytosis
E. passive transport
F. facilitated diffusion
G. pinocytosis
H. receptor-mediated endocytosis
I. exocytosis
J. Haut. (2007). Pre-AP Biology.
_______46. diffusion across a biological membrane
_______47. moves solutes against concentration
gradient
_______48. any spread of molecules from area of
higher concentration to area of lower
concentration
_______49. diffusion with help of transport protein
_______50. three types of endocytosis
_______51. engulfing of fluid in membrane vesicles
_______52. diffusion of water across selectively
permeable membrane, from hypotonic to
hypertonic solution
_______53. transport molecules need ATP to function
_______54. enables cell to engulf bulk quantities of
specific large molecules
_______55. how oxygen and carbon dioxide enter
and leave cells
_______56. two types of passive transport
_______57. engulfing of particle in membrane
vesicle
_______58. fusion of membrane-bound vesicle with
membrane, and dumping of contents outside cell
_______59. how a cell might capture a bacterium