$$\text{Water moves from an area of lower solute concentration to higher solute concentration}$$

Question 1

Which of the following best explains why unsaturated fatty acids in phospholipids help maintain membrane fluidity at lower temperatures?

Accepted Answer

Their kinks prevent tight packing of phospholipids, increasing fluidity.

Question 2

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

Accepted Answer

It will swell and possibly burst because water will move into the cell.

Question 3

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

Accepted Answer

Oxygen (O₂)

Question 4

What is the main function of the sodium-potassium pump in animal cells?

Accepted Answer

To generate membrane potential by moving Na⁺ out and K⁺ in against their gradients

Question 5

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

Accepted Answer

Cholesterol reduces membrane fluidity at high temperatures and prevents solidification at low temperatures.

Question 6

A plant cell is placed in a hypertonic solution. What process occurs, and what is the result?

Accepted Answer

Plasmolysis; the cell membrane pulls away from the cell wall due to water loss.

Question 7

Which of the following best describes facilitated diffusion?

Accepted Answer

Passive movement of molecules down their concentration gradient via transport proteins.

Question 8

Which type of membrane protein is most likely to function as a receptor for signal transduction?

Accepted Answer

Integral transmembrane protein

Question 9

What is the primary difference between channel proteins and carrier proteins in membrane transport?

Accepted Answer

Channel proteins form hydrophilic tunnels, while carrier proteins change shape to move molecules.

Question 10

Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$$	ext{Water moves from an area of lower solute concentration to higher solute concentration}$$

Question 11

A patient is given an intravenous solution that is hypertonic relative to their blood cells. What is the most likely outcome for the cells?

Accepted Answer

Cells will shrink as water leaves the cells.

Question 12

Which process is responsible for the secretion of insulin from pancreatic cells?

Accepted Answer

Exocytosis

Question 13

Which of the following best describes cotransport in biological membranes?

Accepted Answer

The downhill diffusion of one solute powers the uphill transport of another.

Question 14

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

Accepted Answer

DNA replication

Question 15

A nerve cell rapidly transports K⁺ ions into the cell and Na⁺ ions out of the cell. Which type of transport is this, and what energy source is used?

Accepted Answer

Active transport; energy from ATP hydrolysis

Question 16

Which of the following best explains why polar molecules like glucose require transport proteins to cross the plasma membrane?

Accepted Answer

Their polarity prevents them from passing through the hydrophobic core of the membrane.

Question 17

Which of the following scenarios best illustrates the concept of selective permeability?

Accepted Answer

A cell membrane allows O₂ to diffuse but requires a protein for glucose transport.

Question 18

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic structure with lipids and proteins moving laterally within the bilayer.

Question 19

Which of the following is a real-life example of bulk transport in cells?

Accepted Answer

White blood cells engulfing bacteria by endocytosis.

Question 20

Which of the following equations best represents the hydrolysis of ATP during active transport?

Accepted Answer

$$	ext{ATP} + 	ext{H}_2	ext{O} ightarrow 	ext{ADP} + 	ext{P}_i + 	ext{energy}$$

Membrane Structure and Function: Study Guide for General Biology

Guida di studio - Domande di pratica