Question

multiple choice question which of the transport mechanisms relies only on concentration gradients to provide the \force\ to move materials across the plasma membrane? secondary active transport passive diffusion group translocation transport primary active transport

Explanation:

To solve this, we analyze each option:

• Secondary active transport: Uses energy from ion gradients (often from primary active transport), not just concentration gradients.
• Passive diffusion: Molecules move from high to low concentration (down concentration gradient) without energy, relying only on concentration gradient.
• Group translocation: Involves chemical modification of the substance being transported and requires energy.
• Primary active transport: Uses ATP (energy) to move molecules against concentration gradient.

So passive diffusion relies only on concentration gradients.

Answer:

B. Passive diffusion