<prompt> Amino acid required for formation of thyroxine?TryptophanTyrosineGlutamineCysteine  <response>: Ans. is b i.e., Tyrosine The term thyroid hormone denotes both thyroxine 74 and triodothyronine T3. Both T4 and T3 are iodine derivatives of thyronine. Thyronine is a condensation product of two molecules of amino acid tyrosine. Thyroxine is 3, 5, 3, 5 - tetraiodothyronine and T3 is 3, 5, 3 -triiodothyronine. Thyroid hormones are synthesized and stored in the thyroid follicles as apa of thyroglobulin molecule. 