Final answer:
The procedure in which a man donates part of his liver to his daughter with cystic fibrosis is known as a liver transplant. This is necessary when the liver is significantly affected by the disease and other treatments are inadequate.
Step-by-step explanation:
The procedure you are referring to, where a man donates part of his liver to his daughter who suffers from cystic fibrosis, is called a liver transplant. Cystic fibrosis is a genetic disease that causes damage not only to the lungs, resulting in breathing difficulties and chronic lung infections, but also to other organs, including the liver. If the liver is affected to the point of failure, and no other treatments can compensate for the loss of liver function, a liver transplant may be necessary.
In this case, a living-donor liver transplant is being considered, which implies that a portion of the donor's liver is transplanted to replace the damaged liver of the recipient. Because the liver has a remarkable ability to regenerate, both the donor and recipient can potentially have full liver function after surgery and recovery.