AP Biology Flashcards: Plasma Membrane
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
Describe the hydrophilic part of a phospholipid.
The hydrophilic part is the polar head, which is oriented toward the aqueous environments found inside and outside of the cell.
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Describe the hydrophilic part of a phospholipid.
The hydrophilic part is the polar head, which is oriented toward the aqueous environments found inside and outside of the cell.
Why do the hydrophilic heads of phospholipids face the cell's cytoplasm and the extracellular fluid?
The hydrophilic heads face these areas because both the cytoplasm and the extracellular fluid are aqueous environments, which attract the polar heads.
What is the primary role of the cell membrane's components?
The components of the cell membrane work together to maintain the internal environment of the cell.
What determines the orientation of proteins within the plasma membrane?
Embedded proteins have both hydrophilic and hydrophobic regions that determine their orientation and interaction within the phospholipid bilayer.
Besides phospholipids and proteins, what other molecules are part of the fluid mosaic model?
The fluid mosaic model also includes steroids and carbohydrates embedded within or attached to the dynamic structure.
How are phospholipids oriented to form the plasma membrane?
Phospholipids have hydrophilic polar heads oriented toward the aqueous environments and hydrophobic nonpolar tails facing inward, forming the membrane's core.
A protein is found spanning the entire membrane. What can be inferred about its structure?
The protein must have hydrophobic regions that interact with the membrane's nonpolar core and hydrophilic regions exposed to the aqueous environments on both sides.
Describe the hydrophobic part of a phospholipid.
The hydrophobic part consists of nonpolar tails that face inward, forming the core of the membrane away from aqueous environments.
What is the fluid mosaic model?
The fluid mosaic model describes the plasma membrane as a dynamic structure of phospholipid molecules embedded with proteins, steroids, and carbohydrates that can move laterally.
Why is the plasma membrane described as 'dynamic'?
It is considered dynamic because its components, such as phospholipids and embedded proteins, are not fixed in place and can move laterally.