The body system responsible for eliminating waste as well as maintianing blood pressure, electrolyte, and acid-base balance is the

A. Cholesterols: Cholesterol is a lipid molecule involved in cell membrane structure and as a precursor for steroid hormones, not as a catalyst for biochemical reactions.

B. Triglycerides: Triglycerides are fats used primarily for energy storage and insulation, and they do not function as enzymes.

C. Proteins: Most enzymes are proteins composed of amino acids. Their three-dimensional structure allows them to bind substrates and catalyze biochemical reactions efficiently, making them essential for metabolic processes.

D. Carbohydrates: Carbohydrates serve as energy sources and structural molecules but do not act as enzymes to catalyze reactions.

A. Binding is limited to transport maximums: This concept applies to carrier-mediated transport where saturation can occur, but channel-mediated diffusion does not rely on binding and does not reach a transport maximum in the same way.

B. Substances bind to protein carriers: Carrier proteins facilitate movement by binding specific molecules and undergoing conformational changes. Channel-mediated facilitated diffusion does not involve this binding mechanism.

C. Substances move through fluid-filled, transmembrane proteins: In channel-mediated facilitated diffusion, specific substances pass through aqueous channels formed by transmembrane proteins. These channels allow ions or small polar molecules to move down their concentration gradients without energy input.

D. Facilitated active transport is necessary: Channel-mediated diffusion is passive and does not require ATP. Active transport involves energy to move substances against their concentration gradient, which is not the case here.