Q: Which equation correctly represents the direction of water movement during osmosis?

$$\text{Water moves from high water concentration to low water concentration}$$

Question 1

Which of the following best explains why oxygen ($$O_2) $$can diffuse directly across the cell membrane, while glucose cannot?

Accepted Answer

Oxygen is a small, non-polar molecule, allowing it to pass through the hydrophobic core of the phospholipid bilayer, whereas glucose is large and polar, requiring a transport protein.

Question 2

A red blood cell is placed in a hypotonic solution. Which of the following best describes what will happen to the cell, and why?

Accepted Answer

Water will enter the cell by osmosis, causing the cell to swell and possibly lyse, because the solute concentration is lower outside the cell.

Question 3

Which of the following is a function of membrane proteins that is essential for nerve and muscle function?

Accepted Answer

Transporting ions across the membrane to maintain concentration gradients

Question 4

A patient with cystic fibrosis has a mutation in a chloride channel protein. How does this mutation most directly affect the movement of water across the cell membrane in the lungs?

Accepted Answer

It reduces chloride ion movement, disrupting osmotic balance and causing water to remain inside cells, resulting in thick mucus.

Question 5

Which of the following best describes the role of cholesterol in the cell membrane?

Accepted Answer

Cholesterol adds stability to the membrane by modulating its fluidity.

Question 6

Which equation correctly represents the direction of water movement during osmosis?

Accepted Answer

$$	ext{Water moves from high water concentration to low water concentration}$$

Question 7

Which of the following scenarios is an example of active transport?

Accepted Answer

The sodium-potassium pump moves $$Na^+$$ out of the cell and $$K^+$$ into the cell against their concentration gradients using ATP.

Question 8

A cell is placed in a hypertonic solution. What is the expected outcome, and which principle explains this?

Accepted Answer

The cell will lose water and shrink (crenate) due to osmosis, as water moves from low to high solute concentration.

Question 9

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient through a membrane protein, without energy input.

Question 10

Which of the following is NOT a factor that influences the movement of molecules across the cell membrane?

Accepted Answer

The color of the molecule

Question 11

Which process is responsible for the uptake of large particles, such as bacteria, by white blood cells?

Accepted Answer

Phagocytosis

Question 12

A cell needs to secrete a large quantity of hormones. Which process will it most likely use?

Accepted Answer

Exocytosis

Question 13

Which of the following best describes the function of glycoproteins and glycolipids in the cell membrane?

Accepted Answer

They are involved in cell identity and recognition.

Question 14

Which of the following statements about the phospholipid bilayer is correct?

Accepted Answer

The hydrophilic heads face outward toward the aqueous environment, while the hydrophobic tails face inward.

Question 15

Which type of membrane transport requires energy input from the cell?

Accepted Answer

Active transport

Question 16

A cell is exposed to a toxin that blocks all carrier proteins. Which of the following processes would be most directly affected?

Accepted Answer

Facilitated diffusion of glucose

Question 17

Which of the following best explains why ions such as $$Na^+$$ and $$K^+$$ cannot cross the cell membrane by simple diffusion?

Accepted Answer

They are charged and hydrophilic, so they require specific protein channels to cross the hydrophobic core of the membrane.

Question 18

Which of the following is an example of receptor-mediated endocytosis?

Accepted Answer

A cell taking in specific cholesterol molecules by binding them to membrane receptors before engulfing them.

Question 19

Which of the following best describes the difference between pinocytosis and phagocytosis?

Accepted Answer

Pinocytosis engulfs fluids, while phagocytosis engulfs large particles.

Question 20

A scientist measures the rate of $$CO_2$$ diffusion across a cell membrane and finds it is much faster than that of $$Na^+. $$Which property of the membrane and these molecules best explains this observation?

Accepted Answer

$$CO_2 is $$non-polar and can dissolve in the lipid bilayer, while $$Na^+ is $$charged and requires a channel protein.

Cell Membrane Transport: Structure and Mechanisms

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