Final answer:
The statement is true; unconjugated bilirubin is indeed converted to conjugated bilirubin in the liver by the enzyme UDP-glucuronyl transferase, which makes it water-soluble and excretable.
Step-by-step explanation:
The statement that in the liver, unconjugated bilirubin is converted to conjugated bilirubin via the enzyme UDP-glucuronyl transferase is True. Unconjugated bilirubin, a product of heme breakdown, is transported to the liver bound to albumin. Once in the liver, it is conjugated with glucuronic acid by the enzyme UDP-glucuronyl transferase to form bilirubin monoglucuronide and subsequently bilirubin diglucuronide.
This process allows the formerly water-insoluble unconjugated bilirubin to become water-soluble, facilitating its excretion into the bile duct and eventually into the intestine. Conditions such as Crigler-Najjar syndrome and Gilbert's disease involve deficits in UDP-glucuronyl transferase activity, leading to an accumulation of unconjugated bilirubin in the blood, a condition known as unconjugated hyperbilirubinemia.