True/False
Indicate whether the statement is true or false.
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1. |
During diffusion, molecules diffuse from a region where their concentration is low to a region where their concentration is higher, until the particles are evenly dispersed.
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2. |
When the concentration of dissolved particles outside a cell is equal to the concentration of dissolved particles inside the cell, the cell solution is isotonic.
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3. |
Membranes are selectively permeable if they allow only certain substances to move across them.
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4. |
A cell placed in a strong salt solution would probably burst because of osmosis.
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5. |
Water will diffuse out of a cell when the cell is placed in a hypertonic solution.
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6. |
Osmosis is the diffusion of starch molecules through a selectively permeable membrane.
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7. |
The binding of specific molecules to ion channels controls the ability of particular ions to cross the cell membrane.
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8. |
To pass through a cell membrane, water requires carrier proteins.
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9. |
In facilitated diffusion, carrier proteins require energy to transport substances across the cell membrane.
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10. |
The transport of specific particles down their concentration gradient through a membrane by carrier proteins is known as facilitated diffusion.
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11. |
Diffusion is an active process that requires a cell to expend a great deal of energy.
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12. |
Diffusion through ion channels is a form of active transport.
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13. |
Facilitated diffusion moves molecules and ions against their concentration gradient, while active transport moves molecules and ions down their concentration gradient.
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14. |
Passive transport uses ATP to move molecules against their concentration gradient.
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15. |
In active transport, energy is required to move a substance across a cell membrane.
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16. |
The sodium-potassium pump requires energy to move ions across the cell membrane.
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17. |
The sodium-potassium pump moves sodium ions and potassium ions against their concentration gradient.
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18. |
The sodium-potassium pump transports sodium ions out of a cell while causing potassium ions to move into the cell.
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19. |
The sodium-potassium pump uses ATP.
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20. |
Exocytosis is a process that uses vesicles to capture substances and bring them into a cell.
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21. |
Exocytosis helps the cell rid itself of wastes.
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22. |
During the process of exocytosis, the cell membrane extends to engulf substances that are too big to pass through the cell membrane.
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23. |
Exocytosis does not use energy to expel proteins from the cell.
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24. |
Receptor proteins pump sodium ions into a cell.
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25. |
Receptor proteins may cause the formation of a second messenger molecule inside a cell.
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26. |
A receptor protein sends signals into a cell by transporting a specific molecule through the cell membrane.
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Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.
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27. |
One way that cells maintain homeostasis is by controlling the movement of substances across the cell membrane. _________________________
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28. |
The cell membrane is made up of a double layer called the DNA bilayer. _________________________
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29. |
A phospholipid is made up of a lipid “head” and two fatty acid “tails.” _________________________
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30. |
The nonpolar tails of a phospholipid are attracted to water. _________________________
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31. |
Cell-surface markers face the inside of the cell. _________________________
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32. |
A concentration gradient exists when one area has a higher concentration of a substance than another area does. _________________________
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33. |
The movement down a concentration gradient is called diffusion. _________________________
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34. |
When the solute concentration outside a cell is equal to the solute concentration inside the cell, the cell’s environment is hypotonic. _________________________
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35. |
A cell placed in a high salt solution would swell because of osmosis. _________________________
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36. |
Osmosis is the diffusion of starch molecules through a selectively permeable membrane. _________________________
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37. |
To pass through a cell membrane, water requires carrier proteins. _________________________
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38. |
Facilitated diffusion is an active process that requires a cell to expend a great deal of energy. _________________________
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39. |
Passive transport uses ATP to move molecules against their concentration gradient. _________________________
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40. |
Exocytosis is a process that uses vesicles to capture substances and bring them into a cell. _________________________
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41. |
Cells use exocytosis to export proteins modified by the Golgi apparatus. _________________________
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42. |
Cells communicate by sending chemical signals that carry information to other cells. _________________________
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43. |
Receptor proteins bind only to signals that match the specific color of the binding site. _________________________
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44. |
Receptor proteins may cause the formation of a second messenger molecule inside the cell. _________________________
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Multiple Choice
Identify the choice that best completes the statement or answers the question.
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45. |
As a result of diffusion, the concentration of many types of substances
a.
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always remains greater inside a membrane. |
b.
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eventually becomes balanced on both sides of a membrane. |
c.
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always remains greater outside of a membrane. |
d.
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becomes imbalanced on both sides of a membrane. |
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46. |
Refer to the illustration above. The process shown is called
a.
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osmosis. |
c.
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active transport. |
b.
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facilitated diffusion. |
d.
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diffusion. |
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47. |
Refer to the illustration above. The process shown is called
a.
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osmosis. |
c.
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active transport. |
b.
|
facilitated diffusion. |
d.
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diffusion. |
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48. |
Diffusion is the movement of a substance
a.
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only through a lipid bilayer membrane. |
b.
|
from an area of low concentration to an area of higher concentration. |
c.
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only in liquids. |
d.
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from an area of high concentration to an area of lower concentration. |
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49. |
The dispersal of ink in a beaker of water is an example of
a.
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diffusion. |
c.
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active transport. |
b.
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osmosis. |
d.
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endocytosis. |
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50. |
The diffusion of water into or out of a cell is called
a.
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solubility. |
c.
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selective transport. |
b.
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osmosis. |
d.
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endocytosis. |
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51. |
Osmosis is a type of
a.
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active transport. |
c.
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facilitated diffusion. |
b.
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passive transport. |
d.
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endocytosis. |
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52. |
A cell will swell when it is placed in a(n)
a.
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hypotonic solution. |
c.
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isotonic solution. |
b.
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hypertonic solution. |
d.
|
None of the above |
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53. |
The interior portion of a cell membrane forms a nonpolar zone that
a.
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allows polar molecules to pass through the membrane. |
b.
|
allows food to pass through the membrane. |
c.
|
prevents ions and most large molecules from passing through the membrane. |
d.
|
None of the above |
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54. |
Ions move through ion channels by
a.
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endocytosis. |
c.
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passive transport. |
b.
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diffusion. |
d.
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active transport. |
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55. |
Ion channel gates close the pores of some ion channels in response to
a.
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stretching of the cell membrane. |
b.
|
a change in electrical charge. |
c.
|
the binding of specific molecules to the channel. |
d.
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All of the above |
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56. |
Proteins that act like selective passageways in the cell membrane are known as
a.
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marker proteins. |
c.
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receptor proteins. |
b.
|
channel proteins. |
d.
|
None of the above |
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57. |
Transport proteins that allow ions to pass through the cell membrane are called
a.
|
receptor proteins. |
c.
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ion channels. |
b.
|
marker proteins. |
d.
|
None of the above |
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58. |
Sugar molecules cross the cell membrane by
a.
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active transport. |
c.
|
osmosis. |
b.
|
facilitated diffusion. |
d.
|
gated channels. |
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59. |
Proteins involved in facilitated diffusion are
a.
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carrier proteins. |
c.
|
Both (a) and (b) |
b.
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receptor proteins. |
d.
|
None of the above |
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60. |
Sugar molecules can enter cells through the process of
a.
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exocytosis. |
c.
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osmosis. |
b.
|
facilitated diffusion. |
d.
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ion pumps. |
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61. |
Which of the following does not require energy?
a.
|
diffusion |
c.
|
active transport |
b.
|
endocytosis |
d.
|
sodium-potassium pump |
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62. |
Unlike passive transport, active transport
a.
|
requires energy. |
b.
|
moves substances down their concentration gradient. |
c.
|
does not involve carrier proteins. |
d.
|
All of the above |
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63. |
Both active transport and facilitated diffusion involve
a.
|
ATP. |
b.
|
movement against a concentration gradient. |
c.
|
carrier proteins. |
d.
|
All of the above |
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64. |
Which of the following is a form of active transport?
a.
|
osmosis |
c.
|
facilitated diffusion |
b.
|
diffusion |
d.
|
sodium-potassium pump |
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65. |
The sodium-potassium pump
a.
|
is a carrier protein |
c.
|
is located in the cytoplasm of a cell. |
b.
|
uses passive transport. |
d.
|
transports sugar molecules. |
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66. |
The sodium-potassium pump usually pumps
a.
|
potassium ions out of the cell. |
b.
|
sodium ions into the cell. |
c.
|
potassium ions into the cell. |
d.
|
only potassium ions and sugar molecules. |
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67. |
The sodium-potassium pump
a.
|
increases the concentration of sodium ions inside a cell. |
b.
|
decreases the concentration of sodium ions inside a cell. |
c.
|
increases the concentration of potassium ions inside a cell. |
d.
|
Both (b) and (c) |
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68. |
Proteins and polysaccharides that are too large to move into a cell through diffusion or active transport move in by
a.
|
exocytosis. |
c.
|
the sodium-potassium pump. |
b.
|
endocytosis. |
d.
|
None of the above |
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|
69. |
Molecules that are too large to be moved through the membrane can be transported into the cell by
a.
|
osmosis. |
c.
|
exocytosis. |
b.
|
endocytosis. |
d.
|
diffusion. |
|
|
70. |
Molecules that are too large to be moved across a cell membrane can be removed from the cell by
a.
|
diffusion. |
c.
|
endocytosis. |
b.
|
exocytosis. |
d.
|
osmosis. |
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71. |
Ridding the cell of materials by discharging the materials in vesicles is called
a.
|
osmosis. |
c.
|
exocytosis. |
b.
|
diffusion. |
d.
|
endocytosis. |
|
|
|
|
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72. |
Refer to the illustration above. What happens when the structure labeled A binds to the structure labeled B?
a.
|
Information is sent into the cell. |
c.
|
The cell begins to undergo mitosis. |
b.
|
Proteins enter the cell. |
d.
|
None of the above |
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|
73. |
Refer to the illustration above. What happens when the structure labeled A binds to the structure labeled B?
a.
|
Information is sent into the cell. |
c.
|
The cell begins to swell. |
b.
|
Proteins enter the cell. |
d.
|
Ions enter the cell. |
|
|
74. |
Refer to the illustration above. The structure labeled B in the diagram is an example of a(n)
a.
|
channel protein. |
c.
|
receptor protein. |
b.
|
signal molecule. |
d.
|
ion pump. |
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|
75. |
Signal molecules bind to
a.
|
carbohydrates. |
c.
|
receptor proteins. |
b.
|
marker proteins. |
d.
|
transport proteins. |
|
|
76. |
When a signal molecule binds to a receptor protein, the receptor protein may
a.
|
change the permeability of the membrane. |
b.
|
cause the formation of a second messenger molecule. |
c.
|
catalyze certain chemical reactions in the cell. |
d.
|
All of the above |
|
|
77. |
Which of the following transmit information into a cell by binding to signal molecules?
a.
|
channel proteins |
c.
|
marker proteins |
b.
|
receptor proteins |
d.
|
end proteins |
|
|
78. |
cell membrane : cell ::
a.
|
window : house |
c.
|
door : house |
b.
|
roof : house |
d.
|
wall : house |
|
|
79. |
Which type of molecule forms the cell membrane?
a.
|
protein |
c.
|
nucleic acid |
b.
|
phospholipid |
d.
|
carbohydrate |
|
|
80. |
Phospholipids are molecules that have
a.
|
one polar phosphate head and two polar fatty acid tails. |
b.
|
one polar phosphate head and two nonpolar fatty acid tails. |
c.
|
one polar phosphate head and one polar fatty acid tail. |
d.
|
one nonpolar phosphate head and two polar fatty acid tails. |
|
|
81. |
The interior of the lipid bilayer of a cell membrane forms a nonpolar zone that
a.
|
allows most polar molecules to pass through the membrane. |
b.
|
allows food to pass through the membrane. |
c.
|
repels ions and most polar molecules. |
d.
|
makes the membrane permeable to most molecules. |
|
|
|
|
|
82. |
Refer to the illustration above. The structure labeled A is composed of
a.
|
lipids. |
c.
|
proteins. |
b.
|
carbohydrates. |
d.
|
DNA. |
|
|
83. |
Refer to the illustration above. The structure labeled D is a(n)
a.
|
cell-surface marker. |
c.
|
enzyme. |
b.
|
receptor protein. |
d.
|
transport protein. |
|
|
84. |
Refer to the illustration above. The structure labeled C is a(n)
a.
|
cell-surface marker. |
c.
|
enzyme. |
b.
|
receptor protein. |
d.
|
transport protein. |
|
|
85. |
Proteins in the cell membrane that identify the cell are called
a.
|
cell-surface markers. |
c.
|
enzymes. |
b.
|
receptor proteins. |
d.
|
transport proteins. |
|
|
86. |
As a result of diffusion, the concentration of many types of substances
a.
|
always remains greater inside a membrane. |
b.
|
eventually becomes balanced on both sides of a membrane. |
c.
|
always remains greater outside of a membrane. |
d.
|
becomes imbalanced on both sides of a membrane. |
|
|
87. |
Diffusion is the movement of a substance
a.
|
only through a lipid bilayer membrane. |
b.
|
from an area of low concentration to an area of higher concentration. |
c.
|
only in liquids. |
d.
|
from an area of high concentration to an area of lower concentration. |
|
|
88. |
The dispersal of ink in a beaker of water is an example of
a.
|
diffusion. |
c.
|
active transport. |
b.
|
osmosis. |
d.
|
endocytosis. |
|
|
89. |
Proteins that serve as tunnels for specific substances through the lipid bilayer are
a.
|
cell-surface markers. |
c.
|
receptor proteins. |
b.
|
channel proteins. |
d.
|
enzymes. |
|
|
90. |
Sugar molecules cross the cell membrane by
a.
|
active transport. |
c.
|
osmosis. |
b.
|
facilitated diffusion. |
d.
|
simple diffusion. |
|
|
91. |
Which of the following does not require energy?
a.
|
diffusion |
c.
|
active transport |
b.
|
endocytosis |
d.
|
sodium-potassium pump |
|
|
92. |
Ions move through ion channels by
a.
|
endocytosis. |
c.
|
passive transport. |
b.
|
simple diffusion. |
d.
|
active transport. |
|
|
93. |
The diffusion of water into or out of a cell is called
a.
|
solubility. |
c.
|
selective transport. |
b.
|
osmosis. |
d.
|
endocytosis. |
|
|
94. |
Osmosis is a type of
a.
|
active transport. |
c.
|
simple diffusion. |
b.
|
passive transport. |
d.
|
endocytosis. |
|
|
95. |
How does water pass through the cell membrane?
a.
|
directly through the lipid bilayer |
b.
|
through a water ion pump |
c.
|
through water carrier proteins |
d.
|
through channel proteins just for water |
|
|
96. |
Which of the following statements about an isotonic solution and a cell is correct?
a.
|
The solution has the same solute concentration that the cytoplasm does. |
b.
|
The solution has a higher solute concentration than the cytoplasm does. |
c.
|
A cell in the solution will lose water. |
d.
|
A cell in the solution will gain water. |
|
|
97. |
Unlike passive transport, active transport
a.
|
requires energy. |
b.
|
moves substances down their concentration gradient. |
c.
|
does not involve carrier proteins. |
d.
|
moves water across the cell membrane. |
|
|
98. |
Both active transport and facilitated diffusion involve
a.
|
ATP. |
b.
|
movement against a concentration gradient. |
c.
|
carrier proteins. |
d.
|
channel proteins. |
|
|
99. |
Which of the following is a form of active transport?
a.
|
osmosis |
c.
|
facilitated diffusion |
b.
|
simple diffusion |
d.
|
sodium-potassium pump |
|
|
100. |
The sodium-potassium pump
a.
|
is a carrier protein. |
c.
|
is located in the cytoplasm of a cell. |
b.
|
uses passive transport. |
d.
|
transports sugar molecules. |
|
|
101. |
The sodium-potassium pump usually pumps
a.
|
potassium ions out of the cell. |
b.
|
sodium ions into the cell. |
c.
|
potassium ions into the cell. |
d.
|
only potassium ions and sugar molecules. |
|
|
102. |
How many potassium ions does the sodium-potassium pump move into a cell if it moves six sodium ions out of the cell?
a.
|
two |
c.
|
six |
b.
|
four |
d.
|
eight |
|
|
103. |
Proteins and polysaccharides that are too large to move into a cell through diffusion or active transport move in by
a.
|
exocytosis. |
c.
|
the sodium-potassium pump. |
b.
|
endocytosis. |
d.
|
channel proteins. |
|
|
104. |
Molecules that are too large to be moved across a cell membrane can be removed from the cell by
a.
|
diffusion. |
c.
|
endocytosis. |
b.
|
exocytosis. |
d.
|
osmosis. |
|
|
105. |
Removing materials from a cell in vesicles is called
a.
|
osmosis. |
c.
|
exocytosis. |
b.
|
diffusion. |
d.
|
endocytosis. |
|
|
106. |
Which of the following descriptions of hormones is correct?
a.
|
signal molecules distributed throughout the body |
b.
|
signal molecules that affect all cells in the body |
c.
|
target molecules that communicate through direct contact |
d.
|
target molecules that originate outside the body |
|
|
107. |
Signal molecules bind to
a.
|
carbohydrates. |
c.
|
receptor proteins. |
b.
|
marker proteins. |
d.
|
transport proteins. |
|
|
108. |
Which of the following transmit information into a cell by binding to signal molecules?
a.
|
channel proteins |
c.
|
marker proteins |
b.
|
receptor proteins |
d.
|
signal proteins |
|
|
109. |
What change takes place in the cell membrane if a signal molecule causes a transport protein to open?
a.
|
permeability change |
c.
|
formation of a second messenger |
b.
|
activation of an enzyme |
d.
|
change in chemical reactions |
|
Completion
Complete each statement.
|
|
110. |
The random motion of particles of a substance that causes the substance to move from an area of high concentration to an area of lower concentration is called ____________________.
|
|
111. |
The diffusion of ____________________ through cell membranes is called osmosis.
|
|
112. |
Substances always flow from an area of high concentration to an area of ____________________ concentration.
|
|
113. |
When the concentration of free water molecules is higher outside a cell than inside the cell, water will diffuse ____________________ the cell.
|
|
114. |
If a cell is placed in a(n) ____________________ solution, water will flow out of the cell.
|
|
115. |
If a cell is placed in a(n) ____________________ solution, water will flow into the cell.
|
|
116. |
If a cell is placed in a(n) ____________________ solution, water flows into the cell at a rate that is equal to the rate at which water flows out of the cell.
|
|
117. |
Diffusion of ions through ion channels is a form of ____________________ transport.
|
|
118. |
If the interior of a typical cell is negatively charged, ____________________ charged ions will not require energy to diffuse into the cell using an ion channel.
|
|
119. |
In facilitated diffusion, ____________________ proteins are used to transport substances down their concentration gradient.
|
|
120. |
In ____________________ ____________________, carrier proteins do not require energy to transport amino acids into a cell.
|
|
121. |
Carrier proteins ____________________ shape to transport sugars to the interior of cells.
|
|
122. |
A cell does not expend ____________________ when diffusion takes place.
|
|
123. |
Active transport requires the use of ____________________ by a cell.
|
|
124. |
The ____________________-____________________ pump transports ions against their concentration gradients.
|
|
125. |
The sodium-potassium pump uses energy supplied by ____________________.
|
|
126. |
The sodium-potassium pump prevents the accumulation of ____________________ ions inside the cell.
|
|
127. |
The movement of a substance into a cell by a vesicle is called ____________________.
|
|
|
|
|
128. |
Refer to the illustration above. The process shown in figure B is called ____________________.
|
|
129. |
Refer to the illustration above. Cells often engulf extracellular particles and fluid, as shown in figure A. This is called ____________________.
|
|
130. |
Refer to the illustration above. The process shown in figure B is called ____________________.
|
|
131. |
Refer to the illustration above. The process shown in figure A is called ____________________.
|
|
132. |
Receptor proteins can change the ____________________ of the cell membrane.
|
|
133. |
Receptor proteins may act as ____________________, catalyzing certain chemical reactions inside the cell.
|
|
134. |
In the cell membrane, proteins that transmit information into the cell by responding to signal molecules are called ____________________.
|
|
135. |
One way cells maintain homeostasis is by controlling the movement of substances across the cell ____________________.
|
|
136. |
A(n) ____________________ is a specialized lipid made of a phosphate head and two fatty acid tails.
|
|
137. |
The phosphate head of a phospholipid is attracted to water because it is ____________________.
|
|
138. |
The fatty acid tails of a phospholipid are repelled by water because they are ____________________.
|
|
139. |
The phospholipids form a barrier through which only small, ____________________ substances can pass.
|
|
140. |
Ions and most polar molecules are repelled by the ____________________ interior of the lipid bilayer.
|
|
141. |
____________________ – ____________________ markers are attached to the cell surface and have sugars attached to their protein.
|
|
142. |
Proteins that aid in moving substances into and out of cells are called ____________________ proteins.
|
|
143. |
____________________ are proteins in the cell membrane that help with important biochemical reactions inside the cell.
|
|
144. |
____________________ proteins enable a cell to sense its surroundings by binding to certain substances outside the cell.
|
|
145. |
To reach equilibrium, substances always flow from an area of high concentration to an area of ____________________ concentration.
|
|
146. |
When one area has a higher concentration than another area does, a concentration ____________________ exists.
|
|
147. |
Substances diffuse through a cell membrane either through the lipid bilayer or through ____________________ proteins.
|
|
148. |
Oxygen and carbon dioxide pass through the lipid bilayer by ____________________ diffusion.
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149. |
Diffusion of ions through ion channels is a form of ____________________ transport.
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150. |
Carrier proteins change ____________________ to transport substances to the interior of cells.
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151. |
A cell does not expend ____________________ when diffusion takes place.
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152. |
The diffusion of ____________________ through cell membranes is called osmosis.
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153. |
When the concentration of free water molecules is higher outside a cell than inside the cell, water will diffuse ____________________ the cell.
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154. |
If a cell is placed in a(n) ____________________ solution, water will flow out of the cell.
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155. |
If a cell is placed in a(n) ____________________ solution, water will flow into the cell.
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156. |
If a cell is placed in a(n) ____________________ solution, water flows into the cell at a rate that is equal to the rate at which water flows out of the cell.
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157. |
Active transport requires the use of ____________________ by a cell.
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158. |
The ____________________ – ____________________ pump transports ions against their concentration gradients.
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159. |
The sodium-potassium pump uses energy supplied by ____________________.
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160. |
The sodium-potassium pump prevents the accumulation of ____________________ ions inside the cell.
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161. |
The movement of a substance into a cell by a vesicle is called ____________________.
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162. |
A signaling cell produces a signal that is detected by a ____________________ cell.
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163. |
Light is an environmental ____________________ for the flowering of some plants.
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164. |
In the cell membrane, proteins that bind to specific signal molecules and respond are called ____________________ proteins.
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165. |
Receptor proteins can change the ____________________ of the cell membrane.
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166. |
Receptor proteins may act as ____________________, triggering certain chemical reactions inside the cell.
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Short Answer
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167. |
In addition to its function as a gatekeeper, what are three other functions of the cell membrane?
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168. |
What makes up the lipid bilayer?
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169. |
In the lipid bilayer, what causes one layer of polar heads to face the cell’s cytoplasm and the other layer of heads to face the cell’s surroundings?
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170. |
What characteristic of membrane proteins causes them to be held in the cell membrane?
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171. |
What are four types of proteins in cell membranes?
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172. |
What exists across a cell membrane if equilibrium is not reached?
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173. |
What is the difference between how a molecule crosses the cell membrane in simple diffusion and in facilitated diffusion?
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174. |
What are two types of transport proteins?
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175. |
Why are some water molecules not free to move across the cell membrane?
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176. |
Explain why osmosis is a form of facilitated diffusion.
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177. |
What specific carrier protein moves sodium ions out of a cell and potassium ions into a cell?
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178. |
What is the function of the cell membrane during endocytosis?
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179. |
What are hormones, how are they distributed, and what cells do they affect?
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180. |
What happens to a receptor protein once it binds to a signal molecule?
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181. |
How can the cell’s response to a signal cause a permeability change?
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