Question 1

Which of the following best describes the primary function of the plasma membrane in human cells?

Accepted Answer

It controls what enters and leaves the cell, acting as a selective barrier.

Question 2

Which component of the plasma membrane is most responsible for its fluidity and flexibility?

Accepted Answer

Phospholipids

Question 3

A patient receives a hypertonic intravenous solution. What is the expected effect on their red blood cells?

Accepted Answer

Cells will shrink (crenate) as water leaves the cell.

Question 4

Which type of membrane protein is most likely to function as a channel for ions to pass through the plasma membrane?

Accepted Answer

Integral transmembrane protein

Question 5

What is the main difference between simple diffusion and facilitated diffusion across the plasma membrane?

Accepted Answer

Facilitated diffusion requires membrane proteins, while simple diffusion does not.

Question 6

Which equation best represents the relationship between osmotic pressure ($$\Pi$$), solute concentration ($$C$$), gas constant ($$R$$), and temperature ($$T) in a $$cell?

Accepted Answer

$$\Pi = CRT$$

Question 7

A cell is placed in a solution with lower osmolarity than its cytoplasm. What will happen to the cell?

Accepted Answer

Water will enter the cell, causing it to swell and possibly burst.

Question 8

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

Accepted Answer

Storing genetic information

Question 9

Why are phospholipids well-suited to form the plasma membrane?

Accepted Answer

They have both hydrophobic and hydrophilic regions, allowing them to form a bilayer.

Question 10

Which type of cell junction is most important for preventing leakage between cells in epithelial tissue, such as the skin?

Accepted Answer

Tight junctions

Question 11

A mutation causes the glycocalyx of a cell to change rapidly. What is a possible consequence?

Accepted Answer

The immune system may fail to recognize the cell as damaged, allowing it to replicate uncontrollably.

Question 12

Which process requires energy in the form of ATP to move substances across the plasma membrane?

Accepted Answer

Active transport

Question 13

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

Accepted Answer

They facilitate the movement of water across the membrane.

Question 14

Which type of cell junction allows for the rapid passage of ions and electrical signals between cardiac muscle cells?

Accepted Answer

Gap junctions

Question 15

A cell is placed in an isotonic solution. What will happen to its volume?

Accepted Answer

It will remain unchanged.

Question 16

Which of the following molecules can passively diffuse directly through the phospholipid bilayer?

Accepted Answer

Oxygen

Question 17

Which equation best describes the movement of molecules down a concentration gradient during diffusion?

Accepted Answer

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

Question 18

Which of the following is a consequence of severe plasma membrane damage in burn patients?

Accepted Answer

Substances diffuse freely into and out of cells, compromising concentration gradients.

Question 19

Which of the following best explains why tight junctions are critical in the skin?

Accepted Answer

They prevent water and solutes from leaking between cells, maintaining the skin's barrier function.

Question 20

Which of the following is a function of desmosomes in tissues such as the skin?

Accepted Answer

They provide anchoring strength and allow 'give' between cells, reducing tearing under tension.

Cell Structure and Membrane Function: The Living Units of Anatomy & Physiology

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