Vitamin amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols. The thirteen vitamins required by human metabolism are: vitamin A (retinols and carotenoids), vitamin B (thiamine), vitamin B (riboflavin), vitamin B (niacin), vitamin B (pantothenic acid), vitamin B (pyridoxine), vitamin B (biotin), vitamin B (folic acid or folate), vitamin B (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (quinones). Vitamins have diverse biochemical functions. Some forms of vitamin A function as regulators of cell and tissue
B2 (classification) recognise the shape of a hand up to a visual acuity of 2/60 and/or visual field of less than 5 degrees." This classification has parallels in other sports. The comparative classification in adaptive rowing is LTA-B2. In equestrian, Grade 4 is equivalent to B2. The B2 equivalent for swimming is S12. IBSA handles classification for a number of sports internationally including five-a-side football, goalball and judo. Part of being classified involves assessing vision for factors including visual acuity, contrast sensitivity, color vision, motion detections and visual field. When being assessed into this class by the IBSA, the process first includes