Q: Which equation correctly represents the relationship between diffusion rate ($$R$$), surface area ($$A$$), concentration gradient ($$\Delta C$$), and membrane thickness ($$d$$)?

$$R = \frac{A \times \Delta C}{d}$$

Question 1

Which of the following best describes the role of membrane proteins in cellular transport?

Accepted Answer

They facilitate the movement of specific molecules across the membrane, often against a concentration gradient.

Question 2

A patient is given a solution with a higher solute concentration than their blood plasma. What is the most likely effect on their red blood cells, and which process is responsible?

Accepted Answer

Cells will shrink due to osmosis.

Question 3

Which equation correctly represents the relationship between diffusion rate ($$R$$), surface area ($$A$$), concentration gradient ($$\Delta C$$), and membrane thickness ($$d$$)?

Accepted Answer

$$R = \frac{A 	imes \Delta C}{d}$$

Question 4

A cell is placed in a solution where the concentration of solutes outside the cell is lower than inside. Which direction will water move, and what is this process called?

Accepted Answer

Water will move into the cell by osmosis.

Question 5

Which of the following scenarios best illustrates facilitated diffusion?

Accepted Answer

Glucose molecules moving through a membrane protein from high to low concentration.

Question 6

If the concentration of a solute is equal on both sides of a membrane, what will happen to the net movement of that solute?

Accepted Answer

There will be no net movement of the solute.

Question 7

A researcher increases the temperature of a solution containing cells. What effect will this have on the rate of molecular movement across the cell membrane?

Accepted Answer

The rate will increase because molecules move faster at higher temperatures.

Question 8

Which of the following best explains why large polar molecules require membrane proteins to cross the cell membrane?

Accepted Answer

The hydrophobic core of the lipid bilayer prevents their direct passage.

Question 9

A cell uses energy to move potassium ions into the cell against their concentration gradient. Which process is being described?

Accepted Answer

Active transport

Question 10

Which of the following would most likely increase the rate of diffusion of a substance across a cell membrane?

Accepted Answer

Increasing the concentration gradient across the membrane.

Question 11

A patient with kidney failure is treated with dialysis. Which principle of membrane transport does dialysis most directly utilize?

Accepted Answer

Diffusion of solutes across a semi-permeable membrane.

Question 12

Which of the following best describes the effect of increasing membrane thickness ($$d) on $$the rate of diffusion ($$R$$), according to the equation $$R = \frac{A 	imes \Delta C}{d}$$?

Accepted Answer

The rate of diffusion decreases as membrane thickness increases.

Question 13

Which scenario best demonstrates the concept of selective permeability in biological membranes?

Accepted Answer

A cell allows oxygen to pass freely but restricts the movement of ions.

Question 14

A person drinks a large amount of pure water. What is the most likely effect on their cells, and which process is responsible?

Accepted Answer

Cells will swell due to osmosis.

Question 15

Which of the following is NOT a characteristic of passive transport?

Accepted Answer

It requires energy in the form of ATP.

Question 16

A cell is placed in a hypertonic solution. Which of the following best describes what happens to the cell?

Accepted Answer

The cell loses water and shrinks.

Question 17

Which of the following best explains why oxygen can diffuse directly through the cell membrane, but glucose cannot?

Accepted Answer

Oxygen is small and nonpolar, while glucose is larger and polar.

Question 18

A scientist observes that when the concentration gradient ($$\Delta C) $$across a membrane is doubled, the rate of diffusion ($$R) $$also doubles. Which equation best explains this observation?

Accepted Answer

$$R = k 	imes \Delta C$$

Question 19

Which of the following is an example of a real-life application of active transport in human physiology?

Accepted Answer

The sodium-potassium pump maintaining nerve cell resting potential.

Membrane Transport Mechanisms in Anatomy & Physiology

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