AP Bio Unit 2 Study Guide Flashcards

Vocabulary flashcards covering key concepts from the AP Biology Unit 2 test study guide including cell structures, transport mechanisms, membrane dynamics, and compartmentalization.

Universal Cellular Structures

Cellular structures that are present across all cells, both prokaryotic and eukaryotic.

Apoptosis

Programmed cell death that is mediated and executed by specific cellular organelles.

Surface Area to Volume Ratio

The relationship between a cell's exterior surface area and its internal volume, denoted as $\text{SA:V}$, which dictates cellular efficiency and rate of exchange with the environment.

Fluid Mosaic Model

A structural model of the cell membrane depicting a dynamic phospholipid bilayer containing integrated proteins, polar regions, and nonpolar regions.

Selective Permeability

The feature of the cell membrane that regulates which molecules can pass directly through the phospholipid bilayer versus those requiring protein transport.

Phospholipid Bilayer

The structural portion of the cell membrane responsible for creating a semi-permeable barrier between the internal cellular environment and extracellular surroundings.

Concentration Gradient

The gradual change in the concentration of solutes in a solution as a function of distance across a membrane, directing the movement of individual molecules.

Passive Transport

The movement of substances across a cell membrane along their concentration gradient without the expenditure of ATP.

Active Transport

The movement of substances across a cell membrane against their concentration gradient, requiring cellular energy in the form of ATP.

Aquaporins

Specialized transport proteins that allow water to move directly and rapidly across the plasma membrane.

Diffusion

The net passive movement of particles from a region of higher concentration to a region of lower concentration.

Facilitated Diffusion

A type of passive transport that uses specific membrane proteins to move polar or charged molecules across the membrane along their concentration gradient without ATP.

Osmosis

The passive movement of water molecules across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Tonicity

The capability of an extracellular solution to alter the volume of a cell by affecting osmosis.

Osmolarity

The measure of total solute concentration in a solution; a low osmolarity indicates a high water concentration and a high water potential.

Water Potential

The physical property predicting the direction in which water will flow, determined by solute potential and pressure potential equations.

Hypertonic Environment

An external solution with a higher concentration of solutes relative to the inside of a cell, causing water to flow out of the cell.

Hypotonic Environment

An external solution with a lower concentration of solutes relative to the inside of a cell, causing water to flow into the cell.

Isotonic Environment

An external solution with an equal solute concentration compared to the inside of a cell, resulting in no net water movement.

Sodium-Potassium Pump

A specific membrane-bound transport protein that uses ATP to perform active transport of sodium and potassium ions against their concentration gradients.

Compartmentalization

The organization of eukaryotic cells into distinct membrane-bound organelles to maximize the efficiency of specific biological processes.

Endosymbiotic Theory

The evolutionary theory stating that eukaryotic organelles such as mitochondria and chloroplasts originated from free-living prokaryotes, evidenced by their double membrane layers.