Q: A cell is placed in a solution with a higher concentration of solutes than inside the cell. Which equation best represents the direction of water movement by osmosis?

$$\text{Water moves from low solute concentration (inside cell) to high solute concentration (outside cell)}$$

Question 1

Which of the following best describes the function of the plasma membrane in human cells?

Accepted Answer

It serves as a flexible boundary that selectively controls what enters and leaves the cell, separating intracellular fluid (ICF) from extracellular fluid (ECF).

Question 2

A red blood cell is placed in a solution and begins to shrink. Which of the following best explains this observation?

Accepted Answer

The solution is hypertonic, causing water to move out of the cell by osmosis.

Question 3

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

Accepted Answer

The membrane consists of a bilayer of phospholipids with embedded proteins that can move laterally within the layer.

Question 4

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

Accepted Answer

The cells will swell and may burst due to water entering the cells.

Question 5

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

Accepted Answer

Cholesterol increases the stiffness of the membrane by fitting between the phospholipid tails.

Question 6

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

Accepted Answer

The sodium-potassium pump ($$\mathrm{Na^+-K^+}$$ ATPase) moving $$3\ \mathrm{Na^+}$$ out and $$2\ \mathrm{K^+}$$ into the cell using ATP.

Question 7

Which of the following best explains why facilitated diffusion is necessary for glucose transport across the plasma membrane?

Accepted Answer

Glucose is a large, polar molecule that cannot cross the hydrophobic core of the membrane without a carrier protein.

Question 8

A cell is placed in a solution with a higher concentration of solutes than inside the cell. Which equation best represents the direction of water movement by osmosis?

Accepted Answer

$$	ext{Water moves from low solute concentration (inside cell) to high solute concentration (outside cell)}$$

Question 9

Which of the following is a function of membrane proteins classified as receptors?

Accepted Answer

They bind specific chemical messengers, triggering signal transduction pathways inside the cell.

Question 10

Which of the following best describes the process of secondary active transport?

Accepted Answer

It uses the energy stored in ion gradients created by primary active transport to move other substances.

Question 11

Which of the following is NOT a function of the glycocalyx?

Accepted Answer

Providing a rigid structural framework for the plasma membrane.

Question 12

A scientist observes that a certain molecule can cross the plasma membrane only when a specific transmembrane protein is present, and the process does not require ATP. Which transport mechanism is most likely involved?

Accepted Answer

Facilitated diffusion

Question 13

Which of the following best explains why animal cells are more susceptible to osmotic imbalances than plant cells?

Accepted Answer

Animal cells lack a cell wall, so they cannot limit hydrostatic and osmotic pressures.

Question 14

Which of the following scenarios best illustrates the function of tight junctions between epithelial cells lining the stomach?

Accepted Answer

They prevent digestive enzymes and acids from leaking between cells into underlying tissues.

Question 15

Which of the following best describes the difference between carrier-mediated and channel-mediated facilitated diffusion?

Accepted Answer

Carrier-mediated diffusion involves transmembrane proteins that change shape to transport specific molecules, while channel-mediated diffusion involves aqueous-filled pores that allow ions or water to pass.

Question 16

Which of the following equations correctly represents the stoichiometry of the sodium-potassium pump?

Accepted Answer

$$3\ \mathrm{Na^+}$$ out, $$2\ \mathrm{K^+} in$$, per $$1$$ ATP hydrolyzed$

Question 17

Which of the following best describes the function of desmosomes in tissues subjected to mechanical stress, such as the skin?

Accepted Answer

They anchor adjacent cells together, providing resistance to tearing and mechanical stress.

Question 18

Which of the following is a real-life example of secondary active transport in the human body?

Accepted Answer

The movement of glucose into intestinal epithelial cells along with sodium ions via a symporter.

Question 19

Which of the following best explains why water can move through the plasma membrane despite being polar?

Accepted Answer

Water is small enough to pass through the lipid bilayer and also moves through specific channels called aquaporins.

LECTURE Chapter 3 - Cell Structure and Function - PART 1

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