Which statement correctly differentiates absorption and adsorption?

• A. Absorption is uptake of compounds needed for synthesis and respiration; Adsorption is when food or other bacteria get caught in the slime layer
• B. Adsorption is uptake; Absorption is catching in slime
• C. Both are the same
• D. Absorption is chemical reaction; Adsorption is a physical process unrelated to slime

Answer: (A)

Absorption vs adsorption describe two different ways substances interact with another material. Absorption is uptake into the interior of a substance or organism—things move from the surrounding medium into the bulk and are used or metabolized, such as nutrients entering a microorganism for growth and respiration. Adsorption, on the other hand, is the sticking of molecules to a surface, like contaminants attaching to the slime layer or to a solid surface without entering the interior.

The statement that absorption is the uptake of compounds needed for synthesis and respiration, while adsorption is when substances get caught on the slime layer, captures this distinction clearly. It emphasizes interior uptake for metabolic needs versus surface adhesion to a boundary like slime.

Why the other ideas don’t fit: reversing the terms would mislabel the processes, saying uptake is adsorption and sticking is absorption. Saying they’re the same ignores the fundamental difference between moving into a interior versus remaining on a surface. And claiming absorption is always a chemical reaction with adsorption as a separate physical process not related to slime overlooks that absorption can involve diffusion or chemical uptake, and adsorption is commonly a surface phenomenon that can occur on slime or other surfaces.