The absorption process where nutrients can freely pass across the intestinal wall is called:

The absorption process where nutrients can freely pass across the intestinal wall is called:

• A. Pinocytosis
• B. Passive diffusion
• C. Facilitated diffusion
• D. Active transport

Answer: (B)

The main idea here is how substances move across the intestinal lining without energy input or specialized carriers. Passive diffusion describes nutrients moving down their concentration gradient directly through the cell membranes, without any energy expenditure or transporter proteins. This is why some small, lipophilic molecules can be absorbed freely. It contrasts with facilitated diffusion, which still goes down the gradient but requires a carrier protein; pinocytosis, which engulfs fluid or particles into vesicles; and active transport, which uses energy to move substances against their gradient. So the absorption process that allows nutrients to pass freely without energy or carriers is passive diffusion.

The main idea here is how substances move across the intestinal lining without energy input or specialized carriers. Passive diffusion describes nutrients moving down their concentration gradient directly through the cell membranes, without any energy expenditure or transporter proteins. This is why some small, lipophilic molecules can be absorbed freely. It contrasts with facilitated diffusion, which still goes down the gradient but requires a carrier protein; pinocytosis, which engulfs fluid or particles into vesicles; and active transport, which uses energy to move substances against their gradient. So the absorption process that allows nutrients to pass freely without energy or carriers is passive diffusion.