Question 1

Which of the following best describes the function of the plasma membrane in a human cell?

Accepted Answer

It acts as a flexible boundary that controls what enters and leaves the cell.

Question 2

A scientist observes a cell with a large number of desmosomes. Which tissue type is this cell most likely part of?

Accepted Answer

Cardiac muscle tissue, where strong anchoring between cells is necessary.

Question 3

Which component of the plasma membrane increases its stability and fluidity?

Accepted Answer

Cholesterol

Question 4

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

Accepted Answer

It will shrink due to water leaving the cell, a process called crenation.

Question 5

Which of the following is TRUE regarding simple diffusion across the plasma membrane?

Accepted Answer

It allows nonpolar, lipid-soluble substances to pass directly through the phospholipid bilayer.

Question 6

What is the main difference between carrier-mediated and channel-mediated facilitated diffusion?

Accepted Answer

Carrier-mediated diffusion involves a shape change in the protein, while channel-mediated diffusion allows substances to pass through a water-filled pore.

Question 7

Which equation correctly represents the relationship between osmolarity and water concentration in a solution?

Accepted Answer

$C_{water} \propto \frac{1}{Osmolarity}$

Question 8

A cell is placed in a solution with lower osmolarity than its cytoplasm. What is the expected outcome?

Accepted Answer

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

Question 9

Which type of membrane protein is most likely to function as a receptor for signal transduction?

Accepted Answer

Integral protein

Question 10

Which of the following best explains why water can move through the plasma membrane despite being polar?

Accepted Answer

Water is small enough to sneak past the nonpolar phospholipid tails and can also move through aquaporins.

Question 11

Which of the following is a function of the glycocalyx on the cell surface?

Accepted Answer

It serves as a biological marker for cell-to-cell recognition.

Question 12

If the plasma membrane suddenly became permeable to Na$^+$ and Cl$^-$ ions, what would be the most likely consequence for the cell?

Accepted Answer

The cell would gain water and swell, possibly bursting, due to increased osmolarity inside.

Question 13

Which of the following best describes the role of gap junctions in cardiac muscle cells?

Accepted Answer

They allow ions and small molecules to pass directly from one cell to another, enabling rapid electrical signaling.

Question 14

Which equation best represents the movement of molecules during passive diffusion?

Accepted Answer

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

Question 15

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

Accepted Answer

Storage of genetic material

Question 16

A solution is isotonic to a cell. What will happen to the cell's volume?

Accepted Answer

It will remain unchanged.

Question 17

Which of the following statements about the cell theory is correct?

Accepted Answer

Cells are the structural and functional unit of life.

Question 18

Which type of cell junction would be most important in preventing leakage of digestive enzymes between cells lining the stomach?

Accepted Answer

Tight junctions

Question 19

Which of the following best describes the composition of the phospholipid bilayer in the plasma membrane?

Accepted Answer

It consists of phospholipids, glycolipids, and cholesterol.

Question 20

Which of the following is a real-world consequence of a rapidly changing glycocalyx in cancer cells?

Accepted Answer

The cancer cell is not recognized as damaged and can replicate unchecked.

Cells: The Living Units – Structure, Diversity, and Function

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