Ready to conquer biology ch 5? In this biology chapter 5 practice quiz, you'll dive into the essentials of diffusion, osmosis and active transport questions to sharpen your understanding of cell biology. Perfect for students looking to boost their confidence before exams, this free cell biology quiz challenges you with real-world scenarios on membrane dynamics and energy flow. Curious how molecules move under different gradients? Test yourself with our diffusion and osmosis quiz and then advance to a hands-on cell transport quiz. Get started now - prove your mastery and ace your next test!
What term describes the passive movement of molecules from an area of higher concentration to an area of lower concentration?
Active transport
Facilitated diffusion
Osmosis
Diffusion
Diffusion is the process by which molecules move down a concentration gradient without energy input. Osmosis specifically refers to the movement of water across a membrane. Active transport requires energy to move substances against their gradient. Read more.
Which process describes the movement of water across a semipermeable membrane?
Diffusion
Active transport
Endocytosis
Osmosis
Osmosis is the passive movement of water molecules through a semipermeable membrane from an area of lower solute concentration to one of higher solute concentration. It occurs without direct energy input. Diffusion generally refers to solutes, whereas osmosis is specific to water movement. Learn more.
In a hypotonic solution, water will move _____ the cell.
Into
No net movement
Both into and out of
Out of
A hypotonic solution has a lower solute concentration outside the cell than inside, so water enters the cell to balance concentrations. This inflow can cause cells to swell and possibly burst. The process does not require energy. More details.
Which form of transport does not require cellular energy?
Simple diffusion
Exocytosis
Active transport
Endocytosis
Simple diffusion moves molecules down their concentration gradient without energy. Endocytosis, active transport, and exocytosis all require cellular energy. Facilitated diffusion also does not need energy but uses transport proteins. See passive transport.
What is the primary energy carrier molecule used in active transport?
NADH
ATP
Glucose
ADP
Adenosine triphosphate (ATP) provides the energy for most active transport processes by transferring a phosphate group to transport proteins. ADP is the lower-energy product after ATP hydrolysis. NADH carries electrons rather than directly powering transport. ATP details.
Which protein type assists polar molecules across a membrane down their concentration gradient?
Channel protein
Carrier protein
Enzyme
Receptor protein
Channel proteins form pores that allow polar or charged molecules to cross membranes passively. Carrier proteins also facilitate diffusion but change shape to move molecules. Enzymes catalyze reactions, and receptor proteins bind signaling molecules. Channel proteins.
In facilitated diffusion, the rate of transport can plateau due to __________.
Concentration equilibrium
Temperature drop
Membrane breakdown
Carrier saturation
Facilitated diffusion uses transport proteins that can become fully occupied, causing a maximum transport rate. Even if the gradient increases further, no additional molecules can be moved until carriers are free. This kinetic behavior resembles enzyme saturation. More info.
Small nonpolar molecules like O2 cross the plasma membrane by ________ diffusion.
Simple
Active
Bulk
Facilitated
Simple diffusion allows small nonpolar molecules to move directly through the lipid bilayer down their concentration gradient without proteins. Facilitated diffusion uses membrane proteins, and active transport uses energy. Bulk transport involves vesicle formation. Reference.
Which process involves engulfing a solid particle into a cell by extending pseudopods?
Exocytosis
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis
Phagocytosis is the uptake of large solid particles by cell membrane extensions called pseudopods. Pinocytosis is uptake of fluids, and receptor-mediated endocytosis uses specific binding. Exocytosis exports material out of the cell. Learn more.
How many sodium ions are pumped out for each two potassium ions pumped in by the Na+/K+ ATPase?
3 Na+ out, 3 K+ in
3 Na+ out, 2 K+ in
2 Na+ out, 3 K+ in
1 Na+ out, 1 K+ in
The Na+/K+ ATPase hydrolyzes one ATP to move three Na+ ions out and two K+ ions into the cell. This electrogenic pump helps maintain membrane potential. Incorrect stoichiometries would disrupt ion gradients. Details.
Which gradient is maintained by the Na+/K+ pump and contributes to the membrane potential?
Pressure gradient
Chemical gradient only
Electrochemical gradient
Osmotic gradient
The Na+/K+ ATPase establishes both concentration and electrical differences across the membrane, creating an electrochemical gradient. This gradient is critical for nerve impulse transmission and secondary active transport. A chemical gradient alone ignores the electrical component. Reference.
The energy stored in a proton gradient across a membrane is known as ________.
Proton-motive force
Membrane potential
Osmotic pressure
Thermodynamic tension
Proton-motive force refers to the combined chemical and electrical potential created by a proton gradient. It drives ATP synthesis and transport processes. Membrane potential is only the electrical component. More info.
Secondary active transport uses _____ gradients to drive movement of other substances.
Ion
ATP
Glucose
Protein
Secondary active transport harnesses the energy stored in an existing ion gradient, usually created by primary active transport, to move another molecule against its gradient. It does not directly use ATP. Learn more.
Which form of transport would be most directly inhibited by a lack of ATP?
Osmosis
Facilitated diffusion
Sodium-potassium pump
Simple diffusion
The Na+/K+ ATPase requires ATP hydrolysis to function. Without ATP, this primary active transport stops, collapsing ion gradients. Passive processes like osmosis and diffusion do not use ATP directly. Read more.
In cotransport, a symporter moves two substances in ______ direction(s).
One at a time
Opposite
Random
The same
Symporters transport two different molecules or ions simultaneously in the same direction across a membrane. Antiporters move substances in opposite directions. Symport is a form of secondary active transport. Details.
Which statement best explains why ion channels can be selective for specific ions?
They bind ions irreversibly
They pump ions using ATP
They open permanently regardless of conditions
The size and charge of the channel pore fit only certain ions
Ion channels have selectivity filters composed of specific amino acid residues that match an ion's size and charge, allowing only certain ions to pass. They do not use ATP directly and are gated rather than permanently open. Irreversible binding would block the channel. More details.
A chemical uncoupler like DNP disrupts ATP synthesis by ________.
Blocking electron transport
Inhibiting ATP synthase directly
Allowing protons to flow back without using ATP synthase
Increasing membrane rigidity
DNP dissipates the proton gradient by carrying protons across the membrane, bypassing ATP synthase and releasing energy as heat. Electron transport may continue but ATP generation stops. It does not directly inhibit the enzyme or alter membrane rigidity. Read more.
Which of the following describes primary active transport?
Bulk movement via vesicles
Use of an ion gradient to drive transport
Passive movement down a gradient
Direct use of ATP to move substances against a gradient
Primary active transport uses ATP hydrolysis directly to translocate molecules or ions against their electrochemical gradient. Secondary active transport uses ion gradients. Passive transport does not use energy, and bulk transport involves vesicle formation. Learn more.
An antiporter that exchanges Na+ for Ca2+ in cardiac cells uses which type of transport?
Facilitated diffusion
Primary active transport
Secondary active transport
Endocytosis
The Na+/Ca2+ exchanger uses the energy from the Na+ electrochemical gradient, established by the Na+/K+ pump, to export Ca2+ against its gradient without directly using ATP. This is secondary active transport. Reference.
Opening of K+ leak channels primarily affects which cellular property?
ATP levels
Membrane potential
pH gradient
Overall solute concentration
K+ leak channels allow potassium to move down its concentration gradient, making the inside of the cell more negative and setting the resting membrane potential. They do not directly affect ATP levels or pH. More info.
Which barrier most significantly slows simple diffusion of hydrophilic molecules?
The cytoskeleton
The hydrophobic core of the lipid bilayer
The cell wall
The extracellular matrix
The hydrophobic interior of the lipid bilayer repels polar and charged molecules, hindering their passive diffusion. Other structures do not form continuous impermeable barriers to small solutes. Transport proteins are required for hydrophilic passage. Learn more.
The sodium-proton antiporter helps regulate intracellular pH by exchanging intracellular H+ for extracellular Na+. What drives this exchange?
Direct ATP hydrolysis
Sodium electrochemical gradient
Osmotic pressure
Proton motive force
The Na+ gradient created by the Na+/K+ ATPase provides the energy for the antiporter to export H+ out of the cell in exchange for Na+ entering. No direct ATP is consumed by the exchanger. Proton motive force refers to mitochondrial or bacterial membranes. Reference.
Which equation correctly expresses the electrochemical potential difference (??) for an ion across a membrane?
?? = F??/RT + ln([out]/[in])
?? = RT ln([in]/[out]) + zF??
?? = RT ([out] - [in])/F + z??
?? = RT ln([out]/[in]) + zF??
The electrochemical potential difference combines the concentration term RT ln([out]/[in]) with the electrical term zF??. This equation predicts the direction and energy of ion movement. Alternate forms either invert the ratio or misplace constants. See details.
The flow of protons through the F0 portion of ATP synthase is driven by torque that rotates which subunit to catalyze ATP formation?
Delta subunit
Alpha subunit
Gamma subunit
Beta subunit
Proton flow through F0 causes rotation of the central stalk, primarily the gamma subunit, within F1. This rotation induces conformational changes in the beta subunits where ATP is synthesized. Alpha subunits are structural, and delta links the complex. Learn more.
Uncoupling protein thermogenin in brown adipose tissue generates heat by:
Allowing protons to re-enter the matrix bypassing ATP synthase
Pumping protons out of the matrix
Blocking electron transport
Increasing ATP production
Thermogenin provides an alternative pathway for protons to re-enter the mitochondrial matrix without driving ATP synthase. The energy of the gradient is released as heat. Electron transport continues, but ATP yield decreases. Reference.
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Study Outcomes
Understand the mechanisms of diffusion and osmosis -
Learn how concentration gradients drive passive transport in cell biology quiz scenarios and predict solute movement across membranes.
Differentiate passive and active transport -
Compare diffusion, facilitated diffusion, and active transport processes as outlined in biology ch 5 to identify key regulatory steps.
Apply quantitative reasoning to diffusion rates -
Calculate net movement of molecules and solve sample problems from the diffusion osmosis quiz to reinforce math skills in membrane transport.
Analyze energy requirements for active transport -
Evaluate the role of ATP and proton gradients in moving substances against concentration gradients using active transport questions.
Interpret experimental data in cell biology -
Read and analyze graphs or tables from the biology chapter 5 practice quiz to draw evidence-based conclusions about transport mechanisms.
Evaluate your mastery of key concepts -
Use this free cell biology quiz to assess your understanding of chapter 5 topics and identify areas for further review before exams.
Cheat Sheet
Fick's Law and Diffusion Rates -
Master Fick's Law (J = - D ΔC/Δx) to calculate how fast molecules move across membranes based on concentration gradients. In a diffusion osmosis quiz, you'll use a steeper ΔC or thinner Δx to predict higher flux. Practicing these calculations solidifies your grasp on biology ch 5 quantitative problems.
Osmosis and Water Potential -
Use the water potential equation Ψ = Ψs + Ψp to determine the direction of water movement; remember that Ψs (solute potential) is always negative. A handy mnemonic is "Hippo" for hypotonic (cells swell like hippos) and "Prune" for hypertonic (cells shrink). Applying these concepts in a diffusion osmosis quiz ensures you can tackle any water balance scenario.
Active Transport and ATP Coupling -
Active transport questions often focus on the Na+/K+ pump, which moves 3 Na+ out and 2 K+ in per ATP hydrolyzed, creating an electrochemical gradient. Recognize that ATP hydrolysis provides the free energy needed to move solutes against their gradient (ΔG < 0 for the pump reaction). Practice these scenarios to ace energy-dependent transport items on a cell biology quiz.
Gibbs Free Energy and Metabolic Direction -
Understand ΔG = ΔH - TΔS to predict reaction spontaneity: negative ΔG means an exergonic reaction. ATP hydrolysis (ΔG ≈ - 30.5 kJ/mol) is a key exergonic process that drives endergonic cellular reactions. Familiarity with ΔG calculations anchors your understanding of energy flow in biology ch 5.
Fluid Mosaic Model and Membrane Permeability -
The fluid mosaic model describes membranes as dynamic bilayers of phospholipids with embedded proteins and cholesterol, influencing fluidity and permeability. Small nonpolar molecules cross easily, while large or charged solutes require specific transport proteins or channels. Reviewing common membrane-transport scenarios is essential for any biology chapter 5 practice quiz or cell biology quiz.
