NEET 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: -Answer and Explanation: The movement of a substance across a biological membrane against its concentration gradient with the help of energy input is active transport, which is option b.

Detailed explanation-3: -Osmosis. Osmosis is the diffusion of water through a semipermeable membrane according to the concentration gradient of water across the membrane.

Detailed explanation-4: -When a cell expands energy to move a solute across its membrane against a concentration gradient, this process is called active transport. Active transport is a movement of substances from lower to higher concentration and requires cellular energy to achieve this movement.