Which type of membrane transport allows a client to absorb nutrients from the small intestine into the bloodstream without the use of cellular energy?

• A. Active transport
• B. Endocytosis
• C. Osmosis
• D. Simple diffusion

Answer: (D)

Verified step by step guidance

1. Understand the concept of membrane transport: Membrane transport refers to the movement of substances across the cell membrane. It can be classified into active transport (requires energy) and passive transport (does not require energy).
2. Review the characteristics of passive transport: Passive transport includes processes like simple diffusion, osmosis, and facilitated diffusion. These processes rely on the concentration gradient and do not require cellular energy (ATP).
3. Define simple diffusion: Simple diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration directly through the lipid bilayer of the cell membrane. This process does not require energy and is driven by the concentration gradient.
4. Apply the concept to nutrient absorption: In the small intestine, nutrients like oxygen, carbon dioxide, and small lipid-soluble molecules can move into the bloodstream via simple diffusion because they follow the concentration gradient and do not require cellular energy.
5. Eliminate other options: Active transport requires energy (ATP), endocytosis involves the engulfing of substances by the cell membrane (also energy-dependent), and osmosis specifically refers to the movement of water molecules. None of these match the description of simple diffusion for nutrient absorption.