Question 1

Which of the following best explains why oxygen and carbon dioxide can cross the plasma membrane without the need for transport proteins?

Accepted Answer

They are small, nonpolar molecules that can diffuse directly through the hydrophobic core of the phospholipid bilayer.

Question 2

A patient is accidentally injected with pure water instead of an isotonic saline solution. What is the most likely effect on their red blood cells, and why?

Accepted Answer

The cells will swell and burst because water will move into the cells by osmosis, as the solution is hypotonic relative to the cytoplasm.

Question 3

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It uses ATP to move sodium ions out of the cell and potassium ions into the cell, both against their concentration gradients.

Question 4

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

Accepted Answer

It increases membrane rigidity by restricting the movement of phospholipids.

Question 5

A cell is placed in a hypertonic solution. What will happen to the cell, and what is the underlying mechanism?

Accepted Answer

The cell will lose water and shrink because water moves out of the cell by osmosis.

Question 6

Which of the following is a function of membrane proteins?

Accepted Answer

All of the above: transport, signal reception, structural support, and enzymatic activity.

Question 7

Which equation correctly represents the overall process of cellular respiration in mitochondria?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\ \mathrm{O_2$} \rightarrow 6\ \mathrm{CO_2$} + 6\ \mathrm{H_2O} + \mathrm{ATP}$$

Question 8

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

Their kinks prevent tight packing of phospholipids, allowing more movement within the membrane.

Question 9

A scientist discovers a new protein that allows water to cross the cell membrane much faster than by simple diffusion. This protein is most likely:

Accepted Answer

An aquaporin, which facilitates rapid water transport across the membrane.

Question 10

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of biochemical reactions, increasing the rate of reaction.

Question 11

A cell needs to import a large quantity of glucose, which cannot diffuse directly through the membrane. Which transport mechanism is most likely used?

Accepted Answer

Facilitated diffusion through a specific glucose transporter protein.

Question 12

Which of the following best describes the function of the extracellular matrix in animal tissues?

Accepted Answer

It provides structural support and fills the space between cells with proteins and carbohydrates.

Question 13

Which of the following is an example of an exergonic reaction in cells?

Accepted Answer

The hydrolysis of ATP to ADP and inorganic phosphate.

Question 14

Which of the following scenarios best illustrates the concept of signal transduction?

Accepted Answer

A hormone binds to a receptor protein on the cell surface, triggering a cascade of protein phosphorylation inside the cell.

Question 15

Which of the following best explains why plant cells do not burst when placed in pure water, unlike animal cells?

Accepted Answer

The rigid cell wall provides structural support and prevents excessive expansion.

Question 16

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

Accepted Answer

Storing genetic information.

Question 17

A mutation causes a cell to produce only saturated fatty acids in its membrane phospholipids. What is the most likely consequence for the cell?

Accepted Answer

The membrane will become more rigid, potentially impairing transport and signaling.

Question 18

Which of the following best describes the relationship between ATP and ADP in cellular energy cycles?

Accepted Answer

ATP is hydrolyzed to ADP, releasing energy for cellular work; ADP is then recycled to ATP using energy from cellular respiration.

Question 19

Which of the following is a real-world example of active transport in human physiology?

Accepted Answer

The sodium-potassium pump maintaining nerve cell membrane potential.

Question 20

Which of the following best explains why membrane fluidity is essential for cell health?

Accepted Answer

It allows efficient transport, signaling, and movement of proteins within the membrane, supporting all essential cellular processes.

The Working Cell: Structure, Function, and Membrane Dynamics

Guida di studio - Domande di pratica

Study guide - Flashcard