The movement of substances across a cell membrane without the use of energy by the cell.

• A. Osmosis
• B. Passive Transport
• C. Endoplasmic Reticulum
• D. Diffusion

Answer: (B)

Movement without energy means passive transport. Substances move down their concentration gradient without the cell expending ATP. Osmosis and diffusion are both forms of passive transport: diffusion is the spread of particles from higher to lower concentration, while osmosis is the diffusion of water across a semipermeable membrane. Endoplasmic Reticulum is a cell organelle involved in synthesis and trafficking, not a transport process across the membrane, so it doesn’t fit. Because the question asks for the general process describing movement across the membrane without energy, the broad term passive transport best captures this concept since it includes both diffusion and osmosis.