Lipid Metabolism And Ketone Bodies Practice Test

A 4-year-old boy presents with progressive muscle weakness and an enlarged, poorly contracting heart on echocardiogram. Laboratory studies during a period of fasting show hypoglycemia, low serum ketone levels, and elevated creatine kinase. A muscle biopsy reveals lipid droplets accumulating within the sarcoplasm. The transport of which of the following molecules into the mitochondria is most likely impaired in this patient?

A 30-year-old man is participating in a clinical study that requires a 36-hour fast. During this period, his hormonal state is characterized by low insulin and high glucagon levels. This hormonal milieu promotes the breakdown of fatty acids in the liver to provide energy. The primary regulatory step that ensures active beta-oxidation in this state involves the inhibition of which of the following enzymes?