All of the following are true EXCEPT

Analyse each option:- Nutritionally non-essential amino acids can be synthesised in the body. So, their absence from the diet in proteins is not deleterious to human health - option a is correct statement. Selenocysteine is present in Thioredoxin reductase, Glutathione peroxidase, 5' deiodinase, Selenoprotein P - option c is correct statement. Oxaloacetate and alpha ketoglutarate are precursors of aspaate and glutamate. 3-phosphoglycerate is the precursor of serine which in turn can produce glycine - option d is also correct. We are left with option b. Tetrahydrobiopterin is needed for tyrosine biosynthesis, not for tryptophan. Moreover, tryptophan cannot be synthesized in human body!