Biology Honors Study Guide: Cell Membrane, Transport, Circulatory & Respiratory Systems

Comprehensive vocabulary flashcards covering cell membrane components, types of cellular transport, and the coordinated functions of the respiratory and circulatory systems.

Selectively permeable

A property of the cell membrane that allows some substances to pass through while blocking others.

Phospholipid

The main molecule that forms the cell membrane, consisting of a hydrophilic head and hydrophobic tails.

Bilayer

The double layer of phospholipids that forms the structure of the cell membrane.

Hydrophilic

Water-attracted; describes the heads of phospholipids that face outward toward water.

Hydrophobic

Water-avoiding; describes the tails of phospholipids that face inward toward one another.

Protein channel

A membrane protein that helps large or charged molecules cross the cell membrane.

Receptor protein

A protein located in the cell membrane that receives signals from outside the cell.

Cholesterol

A lipid molecule that helps stabilize the cell membrane and maintain its flexibility.

ATP

The molecule that directly supplies energy for many cellular activities, including active transport.

Concentration gradient

A difference in the concentration of a substance between two areas.

Equilibrium

The state reached when molecules are evenly distributed and there is no net movement from one area to another.

Diffusion

The passive movement of molecules from an area of high concentration to an area of low concentration without using energy.

Osmosis

The movement of water across a selectively permeable membrane from higher water concentration to lower water concentration.

Facilitated diffusion

The passive movement of substances from high to low concentration with the help of a membrane protein, requiring no cellular energy.

Active transport

The movement of substances against a concentration gradient from low concentration to high concentration using energy, often supplied by ATP.

Passive transport

Transport that moves substances down a concentration gradient without requiring cellular energy (ATP), such as diffusion, osmosis, and facilitated diffusion.

Endocytosis

The movement of materials into a cell by forming a vesicle.

Exocytosis

The release of materials from a cell when a vesicle fuses with the cell membrane.

Alveoli

Tiny air sacs in the lungs where gas exchange occurs, characterized by very thin walls and a large surface area.

Capillaries

Small blood vessels that surround the alveoli to facilitate gas exchange.

Hemoglobin

The protein in red blood cells that binds to and carries oxygen.

Cellular respiration

The process in which body cells use oxygen and produce carbon dioxide as a waste product.