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

$\text{Net movement} = \text{chemical gradient} + \text{electrical gradient}$

Question 1

Which property of phospholipids allows them to form the bilayer structure of cellular membranes?

Accepted Answer

They are amphipathic, containing both hydrophilic heads and hydrophobic tails.

Question 2

According to the fluid mosaic model, which statement best describes the arrangement of proteins in the plasma membrane?

Accepted Answer

Proteins are grouped and can move laterally within the fluid phospholipid bilayer.

Question 3

How does cholesterol affect membrane fluidity at different temperatures in animal cells?

Accepted Answer

Cholesterol decreases fluidity at high temperatures and increases fluidity at low temperatures.

Question 4

Which type of fatty acid is most beneficial for maintaining membrane fluidity in cold environments?

Accepted Answer

Unsaturated fatty acids, because their kinks prevent tight packing and maintain fluidity.

Question 5

Which molecules can pass most easily through the plasma membrane by simple diffusion?

Accepted Answer

Small, hydrophobic molecules like $\mathrm{O_2}$ and $\mathrm{CO_2}$.

Question 6

A cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 7

Which equation best represents the movement of water during osmosis?

Accepted Answer

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

Question 8

Which transport mechanism requires energy input and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 9

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

Accepted Answer

To maintain a higher concentration of potassium ions inside the cell and sodium ions outside.

Question 10

Which equation describes the net movement of ions across a membrane due to the electrochemical gradient?

Accepted Answer

$	ext{Net movement} = 	ext{chemical gradient} + 	ext{electrical gradient}$

Question 11

Which type of membrane protein is most likely to be involved in cell-cell recognition?

Accepted Answer

Integral proteins with attached carbohydrates (glycoproteins)

Question 12

Which process allows a cell to take in large particles such as bacteria?

Accepted Answer

Phagocytosis

Question 13

A plant cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

It will become flaccid due to no net water movement.

Question 14

Which equation best represents the energy requirement for active transport?

Accepted Answer

$	ext{Active transport} = 	ext{ATP hydrolysis}$

Question 15

Which statement best describes cotransport?

Accepted Answer

It is the active transport of one substance coupled to the passive transport of another.

Question 16

Which type of endocytosis is most specific for the substances it transports?

Accepted Answer

Receptor-mediated endocytosis

Question 17

What is the consequence of defective LDL receptor proteins in human cells?

Accepted Answer

Cholesterol accumulates in the blood, increasing risk of heart disease.

Question 18

Which equation best represents the relationship between solute concentration and water movement in osmosis?

Accepted Answer

$	ext{Water moves toward higher solute concentration}$

Question 19

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

Accepted Answer

They allow the rapid passage of water molecules across the membrane.

Question 20

Which equation best represents the sodium-potassium pump's action per cycle?

Accepted Answer

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

Membrane Structure and Function: The Fluid Mosaic Model and Membrane Transport

Study Guide - Practice Questions