Summary:
- Active transport uses energy in the form of ATP (adenosine triphosphate) that is produced by cellular respiration.
- In active transport, the particles move across a cell membrane from a lower concentration to a higher concentration.
- Active transport is the energy-requiring process of pumping molecules and ions across membranes "uphill" - against a concentration gradient.
- Keeping a stable internal environment requires constant adjustments as conditions change inside and outside the cell.
- The adjusting of systems within a cell is called homeostatic regulation.