Q: Which of the following equations correctly represents the relationship between osmolarity, solute concentration, and water movement across a membrane?

$$\text{Osmolarity} = \frac{\text{Number of solute particles}}{\text{Volume of solvent}}$$

Question 1

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

Accepted Answer

A flexible bilayer of phospholipids with proteins and carbohydrates embedded or attached, allowing dynamic movement and specialized functions.

Question 2

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

Accepted Answer

The cell will shrink because water moves out of the cell to the area of higher solute concentration.

Question 3

Which of the following is a function of integral membrane proteins as shown in the images?

Accepted Answer

They act as enzymes, receptors, transporters, and cell adhesion molecules.

Question 4

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

Accepted Answer

Primary active transport

Question 5

A patient receives an intravenous solution that is hypotonic relative to their red blood cells. What is the most likely outcome for the red blood cells?

Accepted Answer

They will swell and possibly burst as water enters the cells.

Question 6

Which of the following best explains why oxygen and carbon dioxide can diffuse directly through the plasma membrane?

Accepted Answer

They are nonpolar and lipid-soluble, allowing them to pass through the hydrophobic core of the lipid bilayer.

Question 7

Which type of cell junction prevents the movement of molecules between adjacent cells, such as in the lining of the intestines?

Accepted Answer

Tight junctions

Question 8

A white blood cell engulfs a bacterium by extending its plasma membrane around the bacterium and internalizing it in a vesicle. This process is best described as:

Accepted Answer

Phagocytosis

Question 9

Which of the following equations correctly represents the relationship between osmolarity, solute concentration, and water movement across a membrane?

Accepted Answer

$$	ext{Osmolarity} = \frac{	ext{Number of solute particles}}{	ext{Volume of solvent}}$$

Question 10

Which of the following best describes the role of the sodium-potassium pump in maintaining the resting membrane potential?

Accepted Answer

It uses ATP to move sodium out of the cell and potassium into the cell, creating an electrochemical gradient.

Question 11

Which of the following is NOT a function of the glycocalyx on the cell surface?

Accepted Answer

Synthesizing ATP for cellular energy

Question 12

A cell is observed to have an abundance of rough endoplasmic reticulum. Which function is this cell most likely specialized for?

Accepted Answer

Protein synthesis for export or membrane insertion

Question 13

Which of the following best explains why facilitated diffusion is necessary for glucose transport into most cells?

Accepted Answer

Glucose is polar and too large to pass through the lipid bilayer without a carrier protein.

Question 14

Which of the following scenarios best illustrates secondary active transport?

Accepted Answer

A sodium-glucose symporter uses the sodium gradient established by the sodium-potassium pump to transport glucose into the cell.

Question 15

Which of the following best describes the function of gap junctions?

Accepted Answer

They allow direct passage of ions and small molecules between adjacent cells.

Question 16

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Uptake of low-density lipoprotein (LDL) cholesterol by liver cells.

Question 17

Which of the following equations correctly represents the hydrolysis of ATP, which provides energy for active transport?

Accepted Answer

$$	ext{ATP} + 	ext{H}_2	ext{O} ightarrow 	ext{ADP} + 	ext{P}_i + 	ext{energy}$$

Question 18

Which of the following best describes the role of cell adhesion molecules (CAMs) in the immune response?

Accepted Answer

They anchor white blood cells to the site of injury or infection, facilitating their migration into tissues.

Question 19

Which of the following best explains why water moves from an area of low solute concentration to an area of high solute concentration during osmosis?

Accepted Answer

Water moves to dilute the higher concentration of solutes, equalizing osmolarity on both sides of the membrane.

Cells: The Living Units – Structure, Function, and Membrane Transport

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