Final answer:
Transport within an organism includes active transport, passive diffusion, facilitated diffusion, co-transport, and endocytosis, with large molecules requiring vesicle transport.
Explanation:
Transport within an organism, particularly at the cellular level, involves various mechanisms that enable the movement of substances across cell membranes. Active transport requires energy to move substances against their concentration gradient, using protein pumps that utilize ATP. Passive diffusion is the movement of substances from a higher to a lower concentration without the use of cellular energy. Similarly, facilitated diffusion involves carrier proteins or channels in the cell membrane to assist the movement of molecules down their concentration gradient without requiring energy.
Co-transport, or secondary active transport, uses the passive transport of one molecule to drive the active transport of another. Endocytosis is a form of active transport where the cell membrane engulfs material to bring it into the cell. Another key aspect of transport mechanisms is vesicle transport, including endocytosis and exocytosis, which is used for large molecules that cannot pass through the plasma membrane.