Question 1

Which of the following best describes the primary function of the plasma membrane?

Accepted Answer

To transport substances across the membrane

Question 2

Passive membrane transport involves the movement of molecules down their concentration gradient. Which equation best represents the driving force for simple diffusion?

Accepted Answer

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

Question 3

Which statement correctly distinguishes passive transport from active transport?

Accepted Answer

Passive transport does not require cellular energy (ATP)

Question 4

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to water movement across the plasma membrane?

Accepted Answer

Water will move out of the cell by osmosis

Question 5

Which of the following substances is most likely to cross the phospholipid bilayer by simple diffusion?

Accepted Answer

Oxygen

Question 6

What property of the plasma membrane determines whether a substance can cross by simple diffusion?

Accepted Answer

The permeability of the substance

Question 7

Which of the following best describes osmosis?

Accepted Answer

Movement of water across a selectively permeable membrane

Question 8

Hydrophilic substances are not automatically permeable to the phospholipid bilayer. What factor primarily determines their ability to cross?

Accepted Answer

The size of the substance

Question 9

A patient is given an intravenous solution that is hypotonic compared to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

Cells will swell and may burst due to water influx

Question 10

Which of the following is NOT a type of passive membrane transport?

Accepted Answer

Active transport

Question 11

If a solute is impermeable to the plasma membrane, what is the most likely way it can cross?

Accepted Answer

By passing through a channel protein

Question 12

Which equation best describes the relationship between solute movement and concentration gradient in simple diffusion?

Accepted Answer

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

Question 13

A cell must spend energy to move a substance against its concentration gradient. What type of transport is this?

Accepted Answer

Active transport

Question 14

Which of the following best explains why hydrophobic substances can cross the phospholipid bilayer easily?

Accepted Answer

They dissolve in the lipid portion of the bilayer

Question 15

Which scenario best illustrates the concept of a concentration gradient?

Accepted Answer

A higher concentration of solute on one side of the membrane compared to the other

Question 16

Which of the following is true regarding the movement of water through the plasma membrane?

Accepted Answer

Water moves through both the lipid bilayer and channel proteins

Question 17

A cell is exposed to a solution with lower solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will gain water and swell

Question 18

Which of the following is a common misconception about passive transport?

Accepted Answer

It requires energy from ATP

Question 19

Which factor does NOT affect the permeability of a substance across the plasma membrane?

Accepted Answer

Number of ribosomes in the cell

Question 20

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient through a channel protein

Plasma Membrane Transport Mechanisms: Passive Transport and Diffusion

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