What Active Transport Fix -
In biology, cells must constantly move substances across their membranes to maintain life. Some substances move passively, like rolling downhill. However, cells often need to move substances in the opposite direction—from a low concentration to a high concentration. This process is called . Think of it as pushing a ball uphill; it requires energy.
Antiport (move opposite directions) – Sodium-calcium exchanger. | what active transport
is the movement of molecules or ions across a cell membrane against their concentration gradient (from an area of low concentration to an area of high concentration). Because this movement opposes the natural tendency of diffusion, it requires an input of chemical energy . In biology, cells must constantly move substances across
| Feature | Active Transport | Passive Transport (Diffusion/Osmosis) | | :--- | :--- | :--- | | Direction | Low → High (against gradient) | High → Low (down gradient) | | Energy Required | Yes (ATP) | No | | Protein Carriers | Yes (pumps) | Maybe (channels or carriers for facilitated diffusion) | | Equilibrium | Creates or maintains disequilibrium | Reaches equilibrium | This process is called