Final answer:
A bone marrow transplant replaces diseased or damaged bone marrow with healthy bone marrow. It is used to treat severe forms of anemia and certain types of cancer. The transplant improves the patient's condition by restoring the production of healthy blood cells.
Step-by-step explanation:
A bone marrow transplant replaces diseased or damaged bone marrow with healthy bone marrow from a donor. This procedure is used to treat various severe forms of anemia, such as thalassemia major and sickle cell anemia, as well as some types of cancer, specifically leukemia. One of the main effects of a successful bone marrow transplant is the improvement in the patient's condition as the new bone marrow starts producing healthy blood cells.