All of the following are true EXCEPT
Absence from the diet of ceain amino acids that are present in most proteins is not deleterious to human health Tetrahydrobiopterin is involved in tryptophan biosynthesis Selenocysteine is an essential component of several mammalian proteins Intermediates of the citric acid cycle and of glycolysis acts as precursors of aspaate, asparagine, glutamate, glutamine, glycine, and serine