Final answer:
Passive transport, simple diffusion is the type of transport that requires no ATP and molecules move freely from high to low concentration.
Step-by-step explanation:
The type of transport described as requiring no ATP and in which molecules move freely from high to low concentration is called passive transport, simple diffusion. In this process, molecules such as gases and small non-polar molecules move across the cell membrane without the need for energy. One example of simple diffusion is the movement of oxygen and carbon dioxide across the respiratory membrane in the lungs.
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