Question

Uphill transport i.e., movement of substances from their lower concentration to their higher concentration occurs in

• A. simple diffusion
• B. facilitated diffusion
• C. active transport
• D. both (b) and (c)

Answer 1

Answer: (C)

active transport

Answer 2

In active transport, the movable carrier proteins are called pumps. They employ $ATP$ energy for transport across the membrane. It is uphill transport, i.e., against concentration gradient and is faster than passive transport. The rate of active transport reaches the maximum when all the protein pumps are being used in transport (saturation effect). Carrier proteins are highly specific like enzymes. They are also sensitive to inhibitors that react with protein side chains.