Question 1

Many cells have a sodium-potassium pump. In order to function, sodium-potassium pumps require

Accepted Answer

A)   ATP.
B)   a channel protein.
C)   no concentration gradient.
D)   ADP.
E)   All of the aboveF) A) and C)
G) None of the above

Question 2

When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because

Accepted Answer

A)   many proteins can move around within the bilayer.
B)   all proteins are anchored within the membrane.
C)   proteins are asymmetrically distributed within the membrane.
D)   all proteins in the plasma membrane are peripheral.
E)   different membranes contain different proteins.F) B) and E)
G) A) and E)

Question 3

In biological membranes, the phospholipids are arranged in a _______, with the _______.

Accepted Answer

A)   bilayer; fatty acids pointing toward each other
B)   bilayer; fatty acids facing outward
C)   single layer; fatty acids facing the interior of the cell
D)   single layer; phosphorus-containing region facing the interior of the cell
E)   bilayer; phosphorus groups in the interior of the membraneF) B) and D)
G) C) and D)

Question 4

Which statement about animal cell junctions is not true?

Accepted Answer

A)   Tight junctions are barriers to the passage of molecules between cells.
B)   Desmosomes allow cells to adhere firmly to one another.
C)   Gap junctions block communication between adjacent cells.
D)   Connexons are made of protein.
E)   The fibers associated with desmosomes are made of protein.F) B) and D)
G) B) and C)

Question 5

The difference between osmosis and diffusion is that

Accepted Answer

A)   diffusion is passive transport, whereas osmosis is active transport.
B)   only in diffusion do molecules move from areas of high concentrations to areas of low concentration.
C)   only diffusion refers to the movement of materials across a semipermeable membrane.
D)   osmosis refers specifically to the movement of water, whereas diffusion is the movement of molecules.
E)   the process of osmosis varies according to the kinds of particles present.F) A) and D)
G) C) and D)

Question 6

The sodium-potassium pump (or Na+-K+ pump)

Accepted Answer

A)   is present in endomembranes.
B)   is an example of a secondary active transporter.
C)   results in the formation of a membrane potential across the plasma membrane.
D)   carries out facilitated diffusion.
E)   is a symporter.F) B) and C)
G) All of the above

Question 7

Channel proteins allow ions that would not normally pass through the cell membrane to pass through via the channel. What property of the channel proteins is responsible for this?

Accepted Answer

A)   A pore of polar amino acid groups
B)   A pore of hydrophobic amino acid groups
C)   A pore of Ca2+
D)   All of the above
E)   None of the aboveF) A) and E)
G) B) and D)

Question 8

You are monitoring the diffusion of a molecule across a membrane. Which of the following will result in the fastest rate of diffusion?

Accepted Answer

A)   An internal concentration of 5 percent and an external concentration of 60 percent
B)   An internal concentration of 60 percent and an external concentration of 5 percent
C)   An internal concentration of 35 percent and an external concentration of 40 percent
D)   An internal concentration of 50 percent and an external concentration of 50 percent
E)   Both a and bF) A) and C)
G) C) and D)

Question 9

Which statement about ion channels is not true?

Accepted Answer

A)   They form pores in the membrane.
B)   They are proteins.
C)   All ions pass through the same type of channel.
D)   Movement through them is from regions of high concentration to regions of low concentration.
E)   Movement through them is by simple diffusion.F) None of the above
G) C) and D)

Question 10

Which of the following molecules is the most likely to diffuse across a cell membrane?

Accepted Answer

A)   Glucose
B)   Na+
C)   A steroid
D)   A common amino acid
E)   Cl-F) None of the above
G) All of the above

Question 11

Amino acids enter cells against their concentration gradients by means of

Accepted Answer

A)   simple diffusion.
B)   facilitated diffusion.
C)   primary active transport.
D)   secondary active transport.
E)   osmosis.F) B) and C)
G) A) and B)

Question 12

What will happen if a red blood cell with an internal salt concentration of about 0.85 percent is placed in a saline solution that is 4 percent?

Accepted Answer

A)   The red blood cell will lose water and shrivel.
B)   The red blood cell will gain water and burst.
C)   The turgor pressure in the cell will increase greatly.
D)   The turgor pressure in the cell will decrease greatly.
E)   The cell will remain unchanged.F) C) and E)
G) A) and B)

Question 13

A protein that forms an ion channel through a membrane is most likely to be

Accepted Answer

A)   a peripheral protein.
B)   a transmembrane protein.
C)   a phospholipid.
D)   an enzyme.
E)   entirely outside the phospholipid bilayer.F) A) and B)
G) C) and D)

Question 14

Which of the following statements about channel proteins is true?

Accepted Answer

A)   They have a central pore of polar amino acids and water.
B)   They are anchored in the hydrophobic bilayer of the plasma membrane.
C)   They are surrounded by nonpolar amino acids.
D)   They are usually gated.
E)   All of the aboveF) A) and B)
G) A) and E)

Question 15

Cells have the ability to take in large molecules by endocytosis and secrete them to the environment by exocytosis. Describe each process and explain why both are important for the cell.

Accepted Answer

Cells take up large particles, foreign c...

Question 16

Osmosis is

Accepted Answer

A)   the diffusion of water across membranes.
B)   the active transport of water across membranes.
C)   unidirectional diffusion of water across membranes.
D)   unaffected by solute concentrations inside cells.
E)   a process that requires energy.F) C) and D)
G) B) and C)

Question 17

In facilitated diffusion, the diffusion rate of a specific molecule across a membrane does not continue to increase as the concentration difference of the molecule across the membrane increases. This is the case because

Accepted Answer

A)   facilitated diffusion requires the use of ATP.
B)   as the concentration difference increases, molecules interfere with one another.
C)   the carrier proteins are saturated.
D)   the transport protein must be of the channel type.
E)   the diffusion constant depends on the concentration difference.F) A) and E)
G) None of the above

Question 18

Which of the following processes does not involve the uptake of materials into the cell?

Accepted Answer

A)   Exocytosis
B)   Pinocytosis
C)   Endocytosis
D)   Receptor-mediated endocytosis
E)   PhagocytsisF) A) and D)
G) D) and E)

Question 19

Osmosis is a specific form of

Accepted Answer

A)   diffusion.
B)   facilitated transport.
C)   active transport.
D)   secondary active transport.
E)   movement of water by carrier proteins.F) B) and C)
G) B) and E)

Question 20

In a hypothetical study, cells are placed in a solution of glucose in which the concentration of glucose is gradually increased. At first, the rate at which glucose enters the cells is found to increase as the concentration of the glucose solution is increased. But when the glucose concentration of the solution is increased above 10 M, the rate no longer increases. Which of the following is the likely mechanism for glucose transport into these cells?

Accepted Answer

A)   Facilitated diffusion via a carrier protein
B)   Facilitated diffusion via a channel protein
C)   Pinocytosis
D)   Secondary active transport
E)   A symporterF) All of the above
G) B) and C)

Exam 6: Cell Membranes

Which of the following molecules is the most likely to diffuse across a cell membrane?

Correct Answer
verified

Channel proteins allow ions that would not normally pass through the cell membrane to pass through via the channel. What property of the channel proteins is responsible for this?

Correct Answer
verified

When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because

Correct Answer
verified

Which statement about animal cell junctions is not true?

Correct Answer
verified

In facilitated diffusion, the diffusion rate of a specific molecule across a membrane does not continue to increase as the concentration difference of the molecule across the membrane increases. This is the case because

Correct Answer
verified

In biological membranes, the phospholipids are arranged in a _, with the _.

Correct Answer
verified

Cells have the ability to take in large molecules by endocytosis and secrete them to the environment by exocytosis. Describe each process and explain why both are important for the cell.

Correct Answer
verified
Cells take up large particles, foreign c...
View Answer

Which of the following processes does not involve the uptake of materials into the cell?

Correct Answer
verified

The difference between osmosis and diffusion is that

Correct Answer
verified

You are monitoring the diffusion of a molecule across a membrane. Which of the following will result in the fastest rate of diffusion?

Correct Answer
verified

Amino acids enter cells against their concentration gradients by means of

Correct Answer
verified

Osmosis is a specific form of

Correct Answer
verified

Which of the following statements about channel proteins is true?

Correct Answer
verified

Osmosis is

Correct Answer
verified

The sodium-potassium pump (or Na⁺-K⁺pump)

Correct Answer
verified

Many cells have a sodium-potassium pump. In order to function, sodium-potassium pumps require

Correct Answer
verified

A protein that forms an ion channel through a membrane is most likely to be

Correct Answer
verified

What will happen if a red blood cell with an internal salt concentration of about 0.85 percent is placed in a saline solution that is 4 percent?

Correct Answer
verified

Which statement about ion channels is not true?

Correct Answer
verified

Correct Answer
verified

Exam 6: Cell Membranes

Which of the following molecules is the most likely to diffuse across a cell membrane?

Correct AnswerverifiedShow Answer

Channel proteins allow ions that would not normally pass through the cell membrane to pass through via the channel. What property of the channel proteins is responsible for this?

Correct AnswerverifiedShow Answer

When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because

Correct AnswerverifiedShow Answer

Which statement about animal cell junctions is not true?

Correct AnswerverifiedShow Answer

In facilitated diffusion, the diffusion rate of a specific molecule across a membrane does not continue to increase as the concentration difference of the molecule across the membrane increases. This is the case because

Correct AnswerverifiedShow Answer

In biological membranes, the phospholipids are arranged in a _______, with the _______.

Correct AnswerverifiedShow Answer

Cells have the ability to take in large molecules by endocytosis and secrete them to the environment by exocytosis. Describe each process and explain why both are important for the cell.

Correct AnswerverifiedCells take up large particles, foreign c...View AnswerShow Answer

Which of the following processes does not involve the uptake of materials into the cell?

Correct AnswerverifiedShow Answer

The difference between osmosis and diffusion is that

Correct AnswerverifiedShow Answer

You are monitoring the diffusion of a molecule across a membrane. Which of the following will result in the fastest rate of diffusion?

Correct AnswerverifiedShow Answer

Amino acids enter cells against their concentration gradients by means of

Correct AnswerverifiedShow Answer

Osmosis is a specific form of

Correct AnswerverifiedShow Answer

Which of the following statements about channel proteins is true?

Correct AnswerverifiedShow Answer

Osmosis is

Correct AnswerverifiedShow Answer

The sodium-potassium pump (or Na+-K+ pump)

Correct AnswerverifiedShow Answer

Many cells have a sodium-potassium pump. In order to function, sodium-potassium pumps require

Correct AnswerverifiedShow Answer

A protein that forms an ion channel through a membrane is most likely to be

Correct AnswerverifiedShow Answer

What will happen if a red blood cell with an internal salt concentration of about 0.85 percent is placed in a saline solution that is 4 percent?

Correct AnswerverifiedShow Answer

Which statement about ion channels is not true?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

In biological membranes, the phospholipids are arranged in a _, with the _.

Correct Answer
verified

Correct Answer
verified
Cells take up large particles, foreign c...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The sodium-potassium pump (or Na⁺-K⁺pump)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified