$$\text{Water moves from regions of high free water concentration to regions of low free water concentration}$$

Question 1

Which of the following best describes the fluid mosaic model of the cell membrane proposed by Singer and Nicolson?

Accepted Answer

A mosaic of proteins embedded in a fluid phospholipid bilayer, allowing lateral movement of both lipids and proteins.

Question 2

What is the primary function of cholesterol in animal cell membranes?

Accepted Answer

To stabilize membrane fluidity across temperature changes.

Question 3

Which of the following membrane components is most directly involved in cell recognition and immune response?

Accepted Answer

Glycolipids and glycoproteins on the outer leaflet

Question 4

A red blood cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will shrink as water leaves the cell to balance solute concentration.

Question 5

Which equation correctly represents the movement of water during osmosis across a semipermeable membrane?

Accepted Answer

$$	ext{Water moves from regions of high free water concentration to regions of low free water concentration}$$

Question 6

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses membrane proteins to transport molecules down their concentration gradient.

Question 7

A mutation causes a cell to lack aquaporins. What is the most likely consequence?

Accepted Answer

The rate of water movement across the membrane will decrease significantly.

Question 8

Which of the following best explains why phospholipid bilayers are impermeable to most biological molecules and ions?

Accepted Answer

The hydrophobic core of the bilayer repels polar and charged molecules.

Question 9

The Na/K pump is an example of which type of membrane transport?

Accepted Answer

Primary active transport

Question 10

Which formula best describes the rate of simple diffusion across a membrane?

Accepted Answer

$$J = -D \frac{dC}{dx}$$

Question 11

A cell is placed in an isotonic solution. What will happen to the cell's volume?

Accepted Answer

It will remain unchanged because water movement is balanced.

Question 12

Which of the following is a function of integral membrane proteins?

Accepted Answer

Forming channels for selective transport of molecules

Question 13

Which type of membrane transport requires energy input from ATP?

Accepted Answer

Active transport

Question 14

Which of the following best describes the role of surface identity markers on the cell membrane?

Accepted Answer

They identify the cell type to other cells.

Question 15

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Membrane fluidity is maintained at low temperatures by the presence of cholesterol.

Question 16

Which process involves the movement of large particles into the cell by engulfing them with the plasma membrane?

Accepted Answer

Phagocytosis

Question 17

Which of the following is true about the movement of proteins and lipids in the cell membrane?

Accepted Answer

Proteins and lipids can diffuse laterally within the membrane.

Question 18

Which type of membrane protein is most likely to function as a transporter for hydrophilic molecules?

Accepted Answer

Integral membrane protein with a transmembrane domain

Question 19

Which of the following best explains why simple diffusion cannot transport glucose across the cell membrane?

Accepted Answer

Glucose is a large, polar molecule and cannot pass through the hydrophobic core of the membrane.

Question 20

Which of the following is a correct statement about the Na/K pump?

Accepted Answer

It moves 3 Na$$^+$$ ions out and 2 K$$^+$$ ions into the cell per ATP hydrolyzed.

Membranes and Lipids: Structure and Function (Chapter 5 Study Notes)

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