In channel mediated facilitated diffusion,

A. Molecular weight of a substance does not affect the rate: The molecular weight affects diffusion because larger molecules move more slowly than smaller ones. Heavier molecules have lower kinetic energy at a given temperature, which slows their movement across membranes.

B. The greater the concentration gradient, the faster the rate: Net diffusion is directly influenced by the difference in concentration between two areas. A steeper concentration gradient increases the driving force for molecules to move, resulting in a faster diffusion rate.

C. The rate is independent of temperature: Temperature affects diffusion because higher temperatures increase the kinetic energy of molecules, making them move faster. Therefore, diffusion rates are not independent of temperature.

D. The lower the temperature, the faster the rate: Lower temperatures reduce molecular motion and kinetic energy, which slows diffusion. Faster diffusion occurs at higher temperatures rather than lower ones.

A. Vitamin D: Vitamin D is fat-soluble and is absorbed along with dietary fats. It is stored in the liver and adipose tissue and plays a key role in calcium and phosphorus regulation.

B. Vitamin C: Vitamin C is water-soluble, not fat-soluble. It dissolves in water, is not stored extensively in the body, and must be obtained regularly through the diet. Its main functions include collagen synthesis and antioxidant protection.

C. Vitamin E: Vitamin E is a fat-soluble antioxidant that protects cell membranes from oxidative damage. It is stored in adipose tissue and the liver for long-term use.

D. Vitamin A: Vitamin A is fat-soluble and essential for vision, immune function, and epithelial tissue health. It is stored in the liver and released as needed.

E. Vitamin K: Vitamin K is fat-soluble and plays a critical role in blood clotting and bone metabolism. It is absorbed with dietary fats and stored in the liver.