This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
During prolonged starvation, the rate of gluconeogenesis depends on 
Select and explain. 
A. Increased alanine levels in liver, B. Decreased cGMP in liver, C. ADP in liver, D. Decreased essential fatty acids in liver
A: Increased alanine levels in liver
Answer: A: Increased alanine levels in liver 
Explanation: Increased alanine levels in liver 

In the fasting state, there is a considerable output of alanine from skeletal muscle, far in excess of its concentration in the muscle proteins that are being catabolized.
It is formed by transamination of pyruvate produced by glycolysis of muscle glycogen and is exported to the liver, where, after transamination back to pyruvate, it is a substrate for gluconeogenesis.
This is the glucose-alanine cycle. Which has two major functions:-


Transport of α -amino groups of amino acids (ammonium ion/ammonia) from muscle to liver
Transport of alanine as a substrate for gluconeogenesis