Q: A cell uses the sodium-potassium pump to maintain ion gradients. Which equation best represents the energy requirement for this process?

$$ \mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P_i} + \text{energy} $$

Question 1

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A fluid bilayer of phospholipids with proteins and carbohydrates embedded and moving laterally.

Question 2

A red blood cell is placed in a hypotonic solution. What will most likely happen to the cell, and why?

Accepted Answer

It will swell and may burst because water will move into the cell by osmosis.

Question 3

Which of the following statements about cholesterol in animal cell membranes is correct?

Accepted Answer

Cholesterol reduces membrane fluidity at moderate temperatures but prevents solidification at low temperatures.

Question 4

Which of the following best explains why hydrophobic molecules can cross the plasma membrane more easily than hydrophilic molecules?

Accepted Answer

Hydrophobic molecules dissolve in the lipid bilayer, while hydrophilic molecules are repelled by the hydrophobic core.

Question 5

A cell uses the sodium-potassium pump to maintain ion gradients. Which equation best represents the energy requirement for this process?

Accepted Answer

$$ \mathrm{ATP} ightarrow \mathrm{ADP} + \mathrm{P_i} + 	ext{energy} $$

Question 6

Which of the following is an example of passive transport across a cell membrane?

Accepted Answer

Diffusion of oxygen from high to low concentration across the lipid bilayer.

Question 7

A plant cell is placed in a hypertonic solution. What is the most likely outcome for the cell?

Accepted Answer

The cell will plasmolyze as water leaves.

Question 8

Which of the following best describes the function of aquaporins in the plasma membrane?

Accepted Answer

They form hydrophilic channels that facilitate rapid water movement across the membrane.

Question 9

Which process is responsible for the uptake of cholesterol from the bloodstream into animal cells?

Accepted Answer

Receptor-mediated endocytosis

Question 10

A cell is placed in an isotonic solution. Which of the following best describes the net movement of water?

Accepted Answer

There is no net movement of water; water moves equally in both directions.

Question 11

Which of the following statements about membrane proteins is correct?

Accepted Answer

Transmembrane proteins are a type of integral protein that span the membrane.

Question 12

Which of the following best explains why active transport is necessary for the sodium-potassium pump?

Accepted Answer

It moves sodium and potassium ions against their concentration gradients, requiring energy input.

Question 13

Which of the following scenarios best illustrates coupled transport (cotransport) in a cell?

Accepted Answer

A proton gradient created by active transport is used to drive the uptake of sucrose into the cell.

Question 14

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Cell-cell recognition by binding to specific molecules on other cells.

Question 15

A patient receives an intravenous solution that is hypertonic relative to their blood cells. What is the most likely effect on the patient's red blood cells?

Accepted Answer

The cells will shrink as water leaves them.

Question 16

Which of the following best describes exocytosis?

Accepted Answer

The release of large molecules from the cell when vesicles fuse with the plasma membrane.

Question 17

Which of the following equations best represents the net movement of water during osmosis?

Accepted Answer

$$ 	ext{Water moves from} ightarrow 	ext{Low solute concentration} ightarrow 	ext{High solute concentration} $$

Question 18

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Synthesis of phospholipids.

Question 19

A cell is observed to engulf a bacterium by surrounding it with its plasma membrane and forming a vesicle. Which process is being described?

Accepted Answer

Phagocytosis

Question 20

Which of the following best explains why membranes rich in unsaturated fatty acids are more fluid than those rich in saturated fatty acids?

Accepted Answer

Unsaturated fatty acids have kinks that prevent tight packing of phospholipids.

Membrane Structure and Function: Chapter 7 Study Notes

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