AP BIOLOGY

Detailed explanation-1: -To move substances against a concentration or electrochemical gradient, a cell must use energy. Active transport mechanisms do just this, expending energy (often in the form of ATP) to maintain the right concentrations of ions and molecules in living cells.

Detailed explanation-2: -Basic types of membrane transport, simple passive diffusion, facilitated diffusion (by channels and carriers), and active transport [8]. Even simple passive diffusion requires energy to cross a bilayer membrane.

Detailed explanation-3: -Active transport requires energy for the process by transporting molecules against a concentration or electrochemical gradient.

Detailed explanation-4: -Cell membrane follows the facilitated diffusion type of transport, where membrane proteins help in transportation by binding to the molecules on the surface. Diffusion with the help of transport protein is known as facilitated diffusion. Transport proteins transport the ions through the cell membrane.

Detailed explanation-5: -In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration-against the concentration gradient.