<prompt> Which enzyme converts Testosterone to dihydroxytestosterone?Aromatase5 a reductase5 a hydroxylase7 a hydroxylase  <response>: Ans. is b i.e., 5 a reductase 5 a reductase is the enzyme which converts testosterone to dihydroxytestosterone DHT. Testosterone is sufficient to support male secondary sexual characteristics Dihydroxytestosterone DHT is however, essential for male type external genitalia to get established. DHT is found to have higher affinity for the receptors, which are responsible for male external genital development, than testosterone. In addition DHT is found to cause prostrate hyperplasia. Hence 5 a reductase is necessary for male type external genitalia to get established 