Question

Active transport of the plasma membrane involves the movement of molecules

• A. along the concentration gradient
• B. against the concentration gradient
• C. both along and against the concentration gradient
• D. neither along nor against the concentration gradient

Answer 1

The correct option is B against the concentration gradient

Active transport involves the expenditure of energy in the form of ATP as the movement of molecules is against the concentration gradient (from low to high concentration) and with the help of special proteins called carrier proteins.

When molecules are transported along the concentration gradient (from higher to lower concentration), there is no utilization of energy. This is called passive transport.