What is not a characteristic of passive transport?

Passive transport is a process through which substances move across cell membranes without the input of energy from the cell. Understanding the characteristics of passive transport is essential to grasp how materials are transported in biological systems.

The correct answer highlights that passive transport does not require cellular energy. This is a fundamental principle of passive transport; substances move along their concentration gradient, meaning they move from areas of higher concentration to areas of lower concentration until equilibrium is reached. This gradient-driven movement relies on inherent kinetic energy of molecules rather than any additional energy source provided by the cell.

In passive transport, molecular diffusion can occur, where molecules spread out evenly in a space. Additionally, because this process does not require energy, it is efficient for transporting small molecules like oxygen and carbon dioxide, which can easily pass through cell membranes.

The characteristics of passive transport help maintain various cellular functions and homeostasis without expending the cell's energy resources. Understanding these principles is critical in studying cellular behavior and transport mechanisms.