The absorption process where nutrients need a protein carrier & energy to pass across the intestinal wall is called:

The absorption process where nutrients need a protein carrier & energy to pass across the intestinal wall is called:

• A. Diffusion
• B. Osmosis
• C. Active transport
• D. Facilitated diffusion

Answer: (B)

The process described is active transport. Substances move across the intestinal lining using a carrier protein and energy, typically because they are going against their concentration gradient. This energy-driven transport is essential for absorbing nutrients that would not move efficiently by diffusion alone. A common example is glucose uptake in the small intestine, which can involve a sodium-dependent transporter that uses the sodium gradient (established by the Na+/K+-ATPase) to bring glucose into cells. This differs from diffusion, which is passive and relies on movement down a concentration gradient without energy. Facilitated diffusion also uses carrier proteins but does not require energy. Osmosis specifically refers to the diffusion of water across a membrane, not nutrient absorption.

The process described is active transport. Substances move across the intestinal lining using a carrier protein and energy, typically because they are going against their concentration gradient. This energy-driven transport is essential for absorbing nutrients that would not move efficiently by diffusion alone. A common example is glucose uptake in the small intestine, which can involve a sodium-dependent transporter that uses the sodium gradient (established by the Na+/K+-ATPase) to bring glucose into cells.

This differs from diffusion, which is passive and relies on movement down a concentration gradient without energy. Facilitated diffusion also uses carrier proteins but does not require energy. Osmosis specifically refers to the diffusion of water across a membrane, not nutrient absorption.