Question 1

Which of the following best describes the fluid mosaic model of biological membranes?

Accepted Answer

A dynamic arrangement of phospholipids, proteins, and cholesterol that move laterally within the membrane.

Question 2

Phospholipids are considered amphipathic molecules because:

Accepted Answer

They have both hydrophilic heads and hydrophobic tails.

Question 3

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

Accepted Answer

Synthesizing proteins.

Question 4

A concentration gradient is defined as:

Accepted Answer

A difference in the concentration of a substance between two areas.

Question 5

Which molecule most easily diffuses across a biological membrane's lipid bilayer, without help of a protein?

Accepted Answer

O\_2

Question 6

What is the primary reason large macromolecules like DNA cannot freely diffuse across the cell membrane?

Accepted Answer

They are too large and often charged, requiring specific transport mechanisms.

Question 7

Which type of membrane protein spans the entire lipid bilayer?

Accepted Answer

Integral membrane protein

Question 8

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion uses membrane proteins to help molecules cross the membrane.

Question 9

Which process is also called the process of cell 'eating'?

Accepted Answer

Phagocytosis

Question 10

If a cell is placed in a solution with a higher concentration of solutes than inside the cell, what will happen?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 11

Which equation best represents the rate of diffusion ($$J) $$across a membrane according to Fick's Law?

Accepted Answer

$$J = D \frac{\Delta C}{\Delta x}$$

Question 12

Which of the following molecules would require a transport protein to cross the cell membrane?

Accepted Answer

Na\^+

Question 13

A cell uses energy to move molecules against their concentration gradient. This process is called:

Accepted Answer

Active transport

Question 14

Which of the following best describes selective permeability?

Accepted Answer

The membrane allows some molecules to pass while restricting others.

Question 15

Which function is performed by membrane proteins to help maintain tissue structure?

Accepted Answer

Anchorage to the cell cytoskeleton and extracellular matrix

Question 16

Which of the following is a real-world example of diffusion?

Accepted Answer

Oxygen moving from the lungs into the blood.

Question 17

Which of the following statements about the movement of molecules across membranes is correct?

Accepted Answer

Small, uncharged molecules can freely diffuse across the lipid bilayer.

Question 18

Which process involves the fusion of vesicles with the plasma membrane to release contents outside the cell?

Accepted Answer

Exocytosis

Question 19

Which of the following is a correct statement about the role of cholesterol in the cell membrane?

Accepted Answer

Cholesterol helps maintain membrane fluidity by preventing tight packing of phospholipids.

Question 20

A cell is exposed to a toxin that blocks all membrane protein function. Which process would be most directly affected?

Accepted Answer

Facilitated diffusion of glucose

Cell Membranes and Membrane Transport: Structure and Function

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