Substances can be transported across cell membranes via active transport, passive diffusion, facilitated diffusion, co-transport, and endocytosis. Active and co-transport require energy, typically in the form of ATP, while passive diffusion and facilitated diffusion do not. Endocytosis involves the cell membrane engulfing materials, also requiring energy.
In biology, substances can be transported across cell membranes using various mechanisms: active transport, passive diffusion, facilitated diffusion, co-transport (or secondary active transport), and endocytosis. Active transport involves moving a substance against its concentration gradient using energy, commonly ATP, whereas passive diffusion allows substances to move along the concentration gradient without the use of cellular energy. Facilitated diffusion is a subtype of passive transport where substances move down their concentration gradient through specific carrier proteins in the cell membrane. Co-transport is another form of active transport where the movement of one substance down its concentration gradient is used to drive the movement of another substance against its gradient. Lastly, endocytosis is an energy-requiring process where substances are engulfed by the cell membrane to enter the cell.
The question probable may be:
What are the various mechanisms involved in the transport of substances across cell membranes, and how do active transport, passive diffusion, facilitated diffusion, co-transport, and endocytosis differ in terms of energy requirements and direction of substance movement?