Membrane Transport Quiz
Questions: 16 · 10 minutes
1. A membrane protein moves calcium ions from a region of lower electrochemical potential to a region of higher electrochemical potential. What must this transport involve?
Simple diffusion through membrane lipids
An energy source coupled to active transport
Passive movement through an open ion channel
Osmosis driven by water concentration
2. A laboratory membrane contains phospholipids but no transport proteins. Which substance would cross it most readily by simple diffusion?
A sodium ion
A glucose molecule
An amino acid with a charged side chain
An oxygen molecule
3. Which statement correctly describes osmosis?
It is the ATP-driven movement of ions through a pump
It is the movement of any solute from high to low concentration
It is the net movement of water across a selectively permeable membrane toward the side with higher solute concentration
It is the uptake of extracellular fluid inside a vesicle
4. A cell must rapidly increase the movement of water across its membrane without moving water against its osmotic gradient. Which protein would help most directly?
A receptor that triggers endocytosis
A sodium-potassium pump
An ATP synthase enzyme
An aquaporin channel
5. How do channel proteins generally differ from carrier proteins in facilitated transport?
Channels form hydrophilic passageways, whereas carriers bind specific solutes and change shape
Channels always use ATP, whereas carriers never use energy
Channels transport only water, whereas carriers transport only ions
Channels move solutes against gradients, whereas carriers move them only down gradients
6. A neuron packages neurotransmitters in vesicles, which fuse with its plasma membrane and release their contents outside the cell. What is this process?
Receptor-mediated endocytosis
Facilitated diffusion
Exocytosis
Primary active transport
7. An animal cell is placed in a solution with a higher concentration of nonpenetrating solutes than the cell interior. What will most likely happen?
Solute will enter until the cell bursts
Water will enter and make the cell swell
Water will leave and the cell will shrink
There will be no net movement of water
8. A cotransporter moves glucose into a cell against its gradient while sodium moves into the cell down its electrochemical gradient. What directly powers glucose transport?
Energy stored in the sodium electrochemical gradient
Glucose diffusing through the phospholipid bilayer
ATP binding directly to the cotransporter
Fusion of a glucose-filled vesicle with the membrane
9. Oxygen concentration is higher outside a cell than inside it. How does oxygen usually enter the cell?
By receptor-mediated endocytosis
By an ATP-powered membrane pump
By simple diffusion through the phospholipid bilayer
By osmosis through an aquaporin
10. A glucose molecule moves into a cell down its concentration gradient through a carrier protein, without direct energy use. Which process is occurring?
Primary active transport
Facilitated diffusion
Simple diffusion through the lipid bilayer
Exocytosis
11. What best describes the net movement of particles during simple diffusion?
From lower concentration to higher concentration using ATP
Through vesicles that merge with the plasma membrane
In one direction regardless of the concentration gradient
From higher concentration to lower concentration because of random molecular motion
12. A cell is placed in an isotonic solution containing nonpenetrating solutes. What is expected?
Water continues moving both ways, but there is no net water movement
All movement of water across the membrane stops
Water enters until the cell bursts
Water leaves until the cell shrinks permanently
13. A white blood cell surrounds and internalizes a large bacterium. This is an example of which transport process?
Facilitated diffusion
Endocytosis, specifically phagocytosis
Exocytosis
Osmosis
14. What distinguishes active transport from passive transport?
Active transport applies only to water molecules
Active transport always uses membrane vesicles
Active transport moves substances only toward lower concentration
Active transport requires an energy source to move a substance against its electrochemical gradient
15. For each ATP molecule used, what does the sodium-potassium pump typically transport?
Two sodium ions out and three potassium ions in
Three sodium ions out and two potassium ions in
Equal numbers of sodium and potassium ions in the same direction
Three sodium ions in and two potassium ions out
16. Which feature of the phospholipid bilayer creates the main barrier to most ions and polar molecules?
Its hydrophobic interior formed by fatty acid tails
Its carbohydrate chains projecting from the surface
Its phosphate groups facing the surrounding water
Its cholesterol molecules carrying substances across