Fill in the following concept map to review the processes by which molecules move across membranes.

Verified step by step guidance

1. Identify the two main types of transport across cell membranes: passive transport and active transport.
2. Recognize that passive transport includes diffusion and facilitated diffusion, which do not require energy.
3. Understand that diffusion involves the movement of molecules from an area of higher concentration to an area of lower concentration, typically involving small or nonpolar molecules.
4. Facilitated diffusion involves the use of transport proteins to move polar molecules and ions across the membrane without energy input.
5. Active transport requires energy, usually in the form of ATP, to move molecules against their concentration gradient, often using transport proteins like pumps.

Key Concepts

Passive Transport

Passive transport is the movement of molecules across a cell membrane without the use of energy. This process occurs along the concentration gradient, meaning substances move from areas of higher concentration to areas of lower concentration. Common examples include diffusion and facilitated diffusion, where specific proteins assist in the transport of molecules.

Active Transport

Active transport is the process by which molecules move across a cell membrane against their concentration gradient, requiring energy input, typically in the form of ATP. This mechanism is crucial for maintaining cellular concentrations of ions and other substances, allowing cells to uptake necessary nutrients and expel waste products efficiently.

Diffusion

Diffusion is a type of passive transport where molecules spread from an area of high concentration to an area of low concentration until equilibrium is reached. This process is essential for the movement of small, nonpolar molecules, such as oxygen and carbon dioxide, across cell membranes, facilitating vital biological functions like respiration.