Category: Science
Question: One of these organic compounds is required for proteins to form blood clots, and sunlight is necessary for the body to produce another. The lack of one fat-soluble type results in night blindness, while beriberi (BARE-ee-BARE-ee) is caused by a diet deficient in one called thiamine. The ascorbic acid one in citrus fruit brought an end to scurvy. For 10 points, name these organic nutrients like A, C, and B1 (B-"ONE") that are only needed in small amounts.
Answer: {vitamins} [accept more specific answers of {Vitamin K, Vitamin D,} or {Vitamin A} until "thiamine" is read]

Vitamins are organic molecules (or a set of closely related molecules called vitamers) that are essential to an organism in small quantities for proper metabolic function. Essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through the diet. For example, vitamin C can be synthesized by some species but not by others; it is not considered a vitamin in the first instance but is in the second.  Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols.
The term vitamin does not include the three other groups of essential nutrients: minerals, essential fatty acids, and essential amino acids.
Major health organizations list thirteen vitamins:

Vitamin A (all-trans-retinols, all-trans-retinyl-esters, as well as all-trans-beta-carotene and other provitamin A carotenoids)
Vitamin B1 (thiamine)
Vitamin B2 (riboflavin)
Vitamin B3 (niacin)
Vitamin B5 (pantothenic acid)
Vitamin B6 (pyridoxine)
Vitamin B7 (biotin)
Vitamin B9 (folic acid and folates)
Vitamin B12 (cobalamins)
Vitamin C (ascorbic acid and ascorbates)
Vitamin D (calciferols)
Vitamin E (tocopherols and tocotrienols)
Vitamin K (phylloquinones, menaquinones, and menadiones)
Some sources include a fourteenth, choline.
Vitamins have diverse biochemical functions. Vitamin A acts as a regulator of cell and tissue growth and differentiation. Vitamin D provides a hormone-like function, regulating mineral metabolism for bones and other organs. The B complex vitamins function as enzyme cofactors (coenzymes) or the precursors for them. Vitamins C and E function as antioxidants. Both deficient and excess intake of a vitamin can potentially cause clinically significant illness, although excess intake of water-soluble vitamins is less likely to do so.
All the vitamins were discovered between 1913 and 1948. Historically, when intake of vitamins from diet was lacking, the results were vitamin deficiency diseases. Then, starting in 1935, commercially produced tablets of yeast-extract vitamin B complex and semi-synthetic vitamin C became available. This was followed in the 1950s by the mass production and marketing of vitamin supplements, including multivitamins, to prevent vitamin deficiencies in the general population. Governments have mandated the addition of some vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. Recommendations for folic acid supplementation during pregnancy reduced risk of infant neural tube defects.