Question 1

Which component of the plasma membrane is primarily responsible for its selective permeability to ions and polar molecules?

Accepted Answer

Membrane proteins

Question 2

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

Accepted Answer

It will shrink (crenate) because water leaves the cell.

Question 3

Which of the following best describes the arrangement of phospholipids in the plasma membrane?

Accepted Answer

Hydrophobic tails face inward, hydrophilic heads face outward toward water.

Question 4

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

Accepted Answer

Active transport

Question 5

A cell uses the sodium-potassium pump to maintain ion gradients. For each cycle, how many sodium ions are pumped out and how many potassium ions are pumped in?

Accepted Answer

$$3$$ sodium out, $$2$$ potassium in

Question 6

Which of the following molecules would most easily diffuse across the plasma membrane without the help of a transport protein?

Accepted Answer

Small, lipophilic molecules

Question 7

During osmosis, water moves across a selectively permeable membrane. In which direction does water move?

Accepted Answer

From an area of low solute concentration to high solute concentration

Question 8

Which of the following is a passive process that uses carrier proteins to move substances down their concentration gradient?

Accepted Answer

Facilitated diffusion

Question 9

A hormone binds to a receptor protein on the plasma membrane, triggering a change in cell activity. What type of membrane protein is involved?

Accepted Answer

Receptor protein

Question 10

Which of the following best explains why ions such as Na\^+ and K\^+ cannot freely cross the plasma membrane?

Accepted Answer

They are hydrophilic and require channel proteins to cross.

Question 11

Which process involves the packaging of extracellular materials in vesicles for import into the cell?

Accepted Answer

Endocytosis

Question 12

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

Accepted Answer

It will remain unchanged.

Question 13

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

Accepted Answer

Acting as a barrier to water

Question 14

Which equation best represents the movement of solute during simple diffusion?

Accepted Answer

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

Question 15

Which of the following processes is used by pancreatic cells to release insulin into the bloodstream?

Accepted Answer

Exocytosis

Question 16

Which factor would most increase the rate of diffusion of a molecule across the plasma membrane?

Accepted Answer

High lipid solubility

Question 17

Which of the following is true about the fluid mosaic model of the plasma membrane?

Accepted Answer

The membrane is composed of a bilayer of phospholipids with embedded proteins that can move laterally.

Question 18

Which type of vesicular transport is responsible for the removal of cellular waste products?

Accepted Answer

Exocytosis

Question 19

A cell is exposed to a solution with a higher concentration of solutes than its cytoplasm. What is the tonicity of the solution, and what will happen to the cell?

Accepted Answer

Hypertonic; the cell will shrink.

Question 20

Which process is described as 'cell eating' and involves the engulfment of large particles by the cell?

Accepted Answer

Phagocytosis

Plasma Membrane & Transport Mechanisms: Study Notes for Anatomy & Physiology

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