AP Biology Flashcards: Membrane Transport
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
What is exocytosis?
Exocytosis is a process requiring energy where vesicles containing large substances fuse with the plasma membrane to release their contents outside of the cell.
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What is exocytosis?
Exocytosis is a process requiring energy where vesicles containing large substances fuse with the plasma membrane to release their contents outside of the cell.
What mechanisms do organisms use to transport large molecules across the plasma membrane?
Organisms use endocytosis and exocytosis, which are energy-requiring processes that use vesicles to move large substances into and out of cells.
How does active transport differ from passive transport regarding concentration gradients?
Passive transport moves molecules down their concentration gradient (high to low), while active transport moves molecules against their concentration gradient (low to high).
A cell needs to export a large protein molecule. Which transport mechanism would it most likely use?
The cell would use exocytosis, an energy-dependent process where a vesicle containing the protein fuses with the plasma membrane to release it.
What is active transport?
Active transport is a process that requires a direct input of energy to move molecules across a membrane, often from a region of low concentration to one of high concentration.
What is a key similarity between active transport and processes like endocytosis?
Both active transport and endocytosis/exocytosis require a direct input of energy to move substances across the plasma membrane.
How do organisms maintain solute and water balance across a membrane?
Organisms use both passive and active transport mechanisms, governed by the selective permeability of the membrane, to control the movement of solutes and water.
If a molecule moves from high to low concentration without the cell expending ATP, what type of transport is occurring?
This is an example of passive transport, as the movement is down the concentration gradient and does not require metabolic energy.
What property of a membrane allows for the formation of concentration gradients?
The selective permeability of membranes, which controls which solutes can pass through, enables the formation and maintenance of concentration gradients.
What is endocytosis?
Endocytosis is a process requiring energy where the cell membrane engulfs large substances to form vesicles and bring them into the cell.
What is passive transport?
Passive transport is the net movement of molecules from a region of high concentration to one of low concentration without requiring metabolic energy.