Which of the following is NOT part of the passive transport process?

• A. Simple diffusion
• B. Osmosis
• C. Facilitated diffusion
• D. Endocytosis

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of passive transport. Passive transport is the movement of molecules across a cell membrane without the use of energy (ATP). It relies on the concentration gradient, moving substances from areas of high concentration to areas of low concentration.
2. Step 2: Review the processes listed in the question: Simple diffusion, osmosis, facilitated diffusion, and endocytosis. Determine which of these processes require energy and which do not.
3. Step 3: Define each term: Simple diffusion is the movement of small, nonpolar molecules directly through the lipid bilayer. Osmosis is the diffusion of water molecules across a selectively permeable membrane. Facilitated diffusion involves the use of protein channels or carriers to move molecules across the membrane, still without energy. Endocytosis, however, is an active transport process that requires energy to engulf substances into the cell via vesicles.
4. Step 4: Compare the characteristics of passive transport processes (simple diffusion, osmosis, facilitated diffusion) with endocytosis. Note that endocytosis does not fit the definition of passive transport because it requires energy input.
5. Step 5: Conclude that the correct answer is endocytosis, as it is not part of the passive transport process.