Biology: Life on Earth 7e
Student Self Test Questions and Answers
Chapter 4: Cell Membrane Structure and Function
Self Test
1. The fluid mosaic model describes membranes as fluid because ___________.
a. the phospholipids of membranes are constantly moving from one layer to the other layer
b. the membrane is composed mainly of water
c. the phospholipid molecules are bonded to one another, making them more moveable
d. the phospholipids move from place to place around the motionless membrane proteins
e. the phospholipids and proteins move from place to place within the bilayer
2. Which of the following types of molecules must pass through membranes via the aqueous pores formed by
membrane proteins?
a. gases such as carbon dioxide and oxygen
b. small polar molecules such as water and ethanol
c. large particles such as bacteria
d. small charged ions such as Na+ and Ca++
3. Diffusion is the movement of molecules from __________.
a. an area of higher concentration of that type of molecule to an area of lower concentration
b. an area of lower concentration of that type of molecule to an area of higher concentration
c. outside the cell to inside the cell
4. In osmosis, water diffuses from the side of the membrane with a higher concentration of water to the side with a
lower concentration of water. What determines the concentration of water in a solution?
a. the volume of the solution
b. the amount of molecules other than water dissolved in the solution
c. the size of the container
.
5. Which of the following processes does a cell use to take up molecules against their concentration gradient?
a. simple diffusion
b. facilitated diffusion
c. active transport
d. endocytosis
e. Both the c and d are correct.
6. What is the difference between active transport and passive transport?
a. Passive transport involves the movement of substances directly through the lipid portion of a
membrane. Active transport requires an input of energy, whereas passive transport does not.
b. Active transport requires energy and is unable to move substances against their concentration
gradient. Passive transport does not require energy and can move substances against their
concentration gradient.
c. Active transport requires energy and can move substances against their concentration gradient.
Passive transport does not require energy and can move substances only down their concentration
gradient.
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
7. Of the following list of substances that can enter a cell, match the order with the correct mechanism by which they
would enter cells: oxygen, water, sodium ions, potassium ions, bacterium. (Note that sodium ions are more
concentrated outside cells than inside; potassium ions are more concentrated inside cells than outside.)
a. simple diffusion, osmosis, facilitated diffusion, active transport, exocytosis
b. osmosis, simple diffusion, facilitated diffusion, active transport, endocytosis
c. passive transport, osmosis, simple diffusion, facilitated diffusion, active transport
d. simple diffusion, osmosis, facilitated diffusion, active transport, endocytosis
e. endocytosis, active transport, active transport, facilitated diffusion, exocytosis
8. Imagine that you are studying cell structure in various organisms in your biology lab. Your instructor gives you a
microscope slide showing two types of cells that have been suspended in pure water. One type of cell swells up until
it bursts. The other cell maintains its shape throughout the experiment. Suggest an explanation for these
observations; assume that both cells were alive at the start of the experiment. Assume also that the concentration of
water inside both types of cells is similar.
a. The cell that burst lacked gap junctions, so water that entered the cell via osmosis could not leak
back out through the junctions.
b. The cell that burst lacked a plasma membrane for regulating osmosis.
c. The cell that remained intact had plasmodesmata that allowed the excess water to leak out, thus
balancing the tendency of water to enter the cell via osmosis.
d. The cell that remained intact had a contractile vacuole for pumping out the excess water that
entered the cell via osmosis.
9. The concentration of sodium ions is lower in the cytoplasm of a heart muscle cell than it is in the extracellular fluid.
By what mechanism does the cell maintain this difference?
a. active transport
b. osmosis
c. facilitated diffusion
d. endocytosis
10. When placed in a certain sucrose solution, the volume of a cell decreases; therefore, the sucrose solution is
__________ to the cell contents.
a. isotonic
b. hypertonic
c. hypotonic
d. cannot determine from given information
11. Choose the substance that will diffuse most rapidly across the plasma membrane.
a. amino acid
b. sodium ion
c. small polar molecule such as water
d. oxygen
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
12. Facilitated diffusion requires __________.
a. a membrane transport protein
b. a concentration gradient
c. energy
d. a membrane transport protein and a concentration gradient
13. During endocytosis, the contents of the endocytic vesicle __________.
a. enter the cell
b. exit the cell
c. enter or exit the cell, always moving down a concentration gradient
14. Which of the following transport processes require(s) energy?
a. facilitated diffusion
b. osmosis
c. endocytosis
d. facilitated diffusion and osmosis
e. facilitated diffusion, osmosis, and endocytosis
15. Membrane fluidity within a phospholipid bilayer is based upon __________.
a. interactions among nonpolar (hydrophobic) lipid tails
b. hydrophilic interactions among polar phospholipid heads
c. the presence of transport proteins in the lipid bilayer
d. the presence of water in the lipid bilayer
16. Recognition proteins function to __________.
a. regulate the movement of ions across the cell membrane
b. bind hormones and alter the intracellular physiology of a cell
c. permit the cells of the immune system to distinguish between pathogens such as bacteria and
cells of your own body
d. all of the above
17. The point at which a substance is evenly dispersed within a fluid __________.
a. is referred to as a dynamic equilibrium
b. occurs when random movements of the substance cease
c. happens when net diffusion is zero
d. Both the first and third answers are correct.
.
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
18. Substances are able to cross the lipid bilayer of a cell at different rates that are unique for each substance. Which
of the following characteristics would favor the simple diffusion of a substance across a cell membrane?
a. low lipid solubility
b. small molecule size
c. small concentration gradients
d. the number of membrane transport proteins for the substance
19. The term tonicity describes the solute concentration of the extracellular fluid relative to the solute concentration of
the aqueous solution known as cytoplasm. In which direction would water flow according to the principles of osmosis
if a cell were placed in a hypertonic solution?
a. Water would flow out of the cell, leaving the cell shriveled and wrinkled.
b. Water would flow into the cell, causing it to swell and perhaps even burst.
c. The net flow of water would be zero because the solute concentrations inside and outside a cell
are equal in a hypertonic medium.
20. Certain microorganisms have a high percentage of unsaturated fatty acids in their membrane. Because of this,
these organisms __________.
a. are able to withstand high temperatures because their membranes are firmer
b. are able to withstand low temperatures because their membranes do not solidify as rapidly
c. are able to carry out sodium ion transport more efficiently than most organisms
d. are more rapidly recognized and destroyed by cells of the immune system
21. A hormone circulating in the bloodstream would most likely bind to __________.
a. a recognition protein
b. a receptor protein
c. a channel protein
d. protein filaments in the cytoplasm
22. Many metabolic poisons work by inhibiting ATP production. Which type of transport would be most affected?
a. osmosis
b. facilitated diffusion
c. active transport
d. simple diffusion
23. The antifungal drug nystatin combines with sterols in the plasma membrane of the fungal cell to disrupt the
membrane and kill the cell. What other cell types might also be affected by nystatin?
a. plant cells
b. animal cells
c. all cell types
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
24. When a drop of food coloring is placed in a glass of water, the spreading out of the molecules of food dye is
caused by __________.
a. the concentration of the molecules of dye
b. the molecules trying to move to a lower concentration
c. the random movement of molecules
d. osmosis
25. Two types of connections between cells called "gap junctions" and "plasmodesmata" are specialized to
__________.
a. prevent the movement of molecules between cells that are tightly joined along ribbons of cell
membrane
b. tightly hold one cell against another at focal points, almost like a spot weld of superglue
c. permit the passage of substances (e.g., ions) between cells through small passageways that
directly link the cytoplasm of one cell to the cytoplasm of another cell
d. None of these are correct.
26. All cells are surrounded by a thin ____________________.
27. The ____________________ consists of all of the internal contents of a cell, except the nucleus in eukaryotic
cells.
28. The membrane components that spontaneously form a bilayer are ____________________.
29. Substances move from high to low concentration by a process called ____________________.
30. During ____________________, energy is used to move substances against their concentration gradient.
31. If a cell is placed in a ____________________ solution, there will be net water movement out of the cell.
32. The type of cell connection that makes the adjacent cells leakproof is a ____________________.
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
33. Label the indicated parts of the cell membrane.
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
34. This is a diagram of one phospholipid from the cell membrane. Label the individual parts.
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
35. Match the steps in the process of diffusion with the sequence of images below:
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
36. Blood cells are used to demonstrate osmosis, since they show obvious shape changes in various solutions. Label
the solution to which each of the following blood cells is reacting.
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Biology: Life on Earth 7e
Student Self Test Questions and Answers
37. Identify the structures of a typical plant cell as seen in the image below.
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