What is the difference between passive and active transport?

• A. Passive transport requires energy; active transport does not
• B. Passive transport requires facilitated diffusion; active transport does not
• C. Passive transport does not require energy; active transport requires energy
• D. There is no difference; both require ATP

Answer: (C)

The distinction between passive and active transport lies in the energy requirements for each process. Passive transport is characterized by the movement of substances across cell membranes without the use of cellular energy. This movement often occurs down a concentration gradient, meaning that substances will naturally move from areas of higher concentration to areas of lower concentration until equilibrium is reached. This process can include simple diffusion, facilitated diffusion, and osmosis.

On the other hand, active transport requires energy, typically in the form of ATP, to move substances against their concentration gradient, from areas of lower concentration to areas of higher concentration. This energy requirement is essential for maintaining concentration differences that are crucial for various cellular functions, such as nutrient uptake, waste removal, and the regulation of ion concentrations.

Thus, the correct answer accurately reflects this fundamental concept in physiology, underscoring that passive transport does not require energy while active transport does.