PrepGo

AP Biology Practice Quiz: Membrane Permeability

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 15 questions to check your progress.

Question 1 of 15

What is the primary consequence of the plasma membrane's structure, which separates the cell's internal and external environments?

All Questions (15)

What is the primary consequence of the plasma membrane's structure, which separates the cell's internal and external environments?

A) It allows all substances to pass freely.

B) It results in selective permeability.

C) It generates energy for cellular processes.

D) It is a feature unique to plant cells.

Correct Answer: B

According to the text, the plasma membrane's structure, with its hydrophobic interior, is what leads to its selective permeability, controlling what enters and leaves the cell.

The selective permeability of a biological membrane is primarily a result of which feature?

A) The presence of a rigid cell wall.

B) The hydrophilic heads of the phospholipids.

C) The hydrophobic interior of the lipid bilayer.

D) The aqueous environment on both sides of the membrane.

Correct Answer: C

The provided content explicitly states that 'selective permeability resulting from its hydrophobic interior.' This nonpolar core restricts the passage of many substances.

Which of the following molecules would most likely pass freely and easily across a plasma membrane?

A) A large polar molecule

B) A small nonpolar molecule

C) An ion

D) A hydrophilic substance

Correct Answer: B

The text specifies that 'Small nonpolar molecules pass freely across the membrane,' because they can easily move through the hydrophobic lipid interior.

A scientist observes that a specific ion is unable to cross the plasma membrane on its own. According to the provided information, what is the most likely reason for this?

A) The ion is too small to be detected by the membrane.

B) The nonpolar tails of the phospholipids repel the charged ion.

C) The cell wall is blocking the ion's passage.

D) The ion is nonpolar and cannot interact with the membrane surface.

Correct Answer: B

The text explains that the 'nonpolar tails of phospholipids prevent most polar molecules and ions from passing.' Ions are charged (hydrophilic) and are repelled by the hydrophobic core of the membrane.

In addition to providing a structural boundary, what is a key function of the cell wall in organisms like plants and bacteria?

A) To facilitate the free passage of all molecules.

B) To synthesize transport proteins.

C) To protect the cell from osmotic lysis.

D) To regulate the passage of nonpolar molecules.

Correct Answer: C

The content clearly states that the cell wall offers 'protection from osmotic lysis,' which is bursting due to excessive water intake.

How does the plasma membrane handle the transport of a large polar molecule compared to a small nonpolar molecule?

A) Both pass freely through the lipid bilayer.

B) The large polar molecule requires a transport protein, while the small nonpolar molecule passes freely.

C) The small nonpolar molecule requires a transport protein, while the large polar molecule passes freely.

D) Both are completely blocked by the membrane and cannot enter the cell.

Correct Answer: B

The text differentiates between these two types of molecules. 'Small nonpolar molecules pass freely,' whereas 'hydrophilic substances like large polar molecules... require embedded channels or transport proteins.'

Based on the provided text, what is true about the movement of water across the plasma membrane?

A) Water is a large polar molecule and cannot cross the membrane at all.

B) Water is nonpolar and passes freely in large quantities.

C) Water is a small polar molecule and can pass through in small amounts.

D) Water requires a cell wall to facilitate its transport.

Correct Answer: C

The text directly addresses this, stating that 'small polar molecules like water can pass in small amounts' despite the generally hydrophobic nature of the membrane's interior.

According to the text, which of the following groups of organisms possess cell walls that provide a structural boundary?

A) Plants, animals, and fungi

B) Animals, protists, and bacteria

C) Plants, fungi, and bacteria

D) Fungi, animals, and archaea

Correct Answer: C

The text lists the organisms with cell walls as 'plants, fungi, bacteria, and archaea.' Option C contains a correct subset of this list.

The passage of most polar molecules and ions across the membrane is prevented by which specific component of the membrane?

A) The hydrophilic phosphate heads

B) The embedded transport proteins

C) The nonpolar phospholipid tails

D) The external cell wall

Correct Answer: C

The content specifies that 'The nonpolar tails of phospholipids prevent most polar molecules and ions from passing,' forming the hydrophobic barrier.

A cell is placed in a solution containing glucose (a large polar molecule) and oxygen (a small nonpolar molecule). Which of the following correctly describes the initial movement of these substances across the cell's plasma membrane without the aid of transport proteins?

A) Both glucose and oxygen will diffuse freely into the cell.

B) Glucose will diffuse freely into the cell, but oxygen will be blocked.

C) Oxygen will diffuse freely into the cell, but glucose will be blocked.

D) Neither substance will be able to cross the membrane.

Correct Answer: C

This question requires applying the rules from the text. Small nonpolar molecules (oxygen) pass freely, while large polar molecules (glucose) are blocked by the hydrophobic interior and require transport proteins.

The cell wall acts as both a structural boundary and a:

A) site of energy production.

B) permeability barrier.

C) mechanism for active transport.

D) location for DNA storage.

Correct Answer: B

The text explicitly describes the cell wall as providing 'a structural boundary and a permeability barrier.'

Which statement best distinguishes the primary permeability role of the plasma membrane from that of the cell wall, based on the text?

A) The plasma membrane is freely permeable, while the cell wall is selectively permeable.

B) The cell wall transports ions, while the plasma membrane transports large polar molecules.

C) The plasma membrane's selective permeability is due to its hydrophobic core, while the cell wall primarily protects against osmotic lysis.

D) The plasma membrane is found only in animals, while the cell wall is found in all other organisms.

Correct Answer: C

This option correctly synthesizes information from the text. The plasma membrane's selectivity comes from its hydrophobic interior, while a key function of the cell wall is providing a structural boundary that protects from osmotic lysis.

A substance is described as hydrophilic. Based on this information and the provided text, what would it likely require to cross the plasma membrane?

A) It must be very small and nonpolar.

B) It can pass freely through the lipid bilayer.

C) It needs an embedded channel or transport protein.

D) It can only cross if a cell wall is absent.

Correct Answer: C

The text states that 'hydrophilic substances like large polar molecules and ions require embedded channels or transport proteins' to move across the membrane.

The plasma membrane effectively separates the aqueous internal environment of a cell from the aqueous external environment primarily because:

A) water cannot pass through the membrane at all.

B) a nonpolar lipid barrier is positioned between two aqueous regions.

C) the cell wall forces water to stay on one side.

D) transport proteins actively pump water out of the cell.

Correct Answer: B

The text describes the membrane's 'hydrophobic interior.' This nonpolar (hydrophobic) region acts as a barrier between the watery (aqueous) environments inside and outside the cell.

A hypothetical cell lacks a cell wall but has a standard plasma membrane. If this cell is placed in a hypotonic solution (pure water), what is the most likely outcome, and why?

A) The cell will be protected from lysis by its selectively permeable membrane.

B) The cell will likely lyse (burst) because water can enter, and there is no cell wall to prevent overexpansion.

C) The cell will shrink because the membrane will pump water out to maintain equilibrium.

D) The cell will remain unchanged because the hydrophobic interior of the membrane prevents any water from entering.

Correct Answer: B

This question requires synthesizing two points. The text states that water can pass into the cell in small amounts. It also states that the cell wall's function is to offer 'protection from osmotic lysis.' Without this protective wall, the cell would take on water in a hypotonic environment and likely burst.