Why is the Krebs cycle also called the final common pathway of the degradation of organic compounds?
The Krebs cycle is known as the final common pathway of the degradation of organic compounds because it is also possible to generate acetyl CoA from the degradation of lipids and proteins. As acetyl CoA is the substrate that triggers the Krebs cycle, this process is known as the final common pathway for being activated by other organic molecules (lipids and proteins) and not only by glucose.
The organism uses energetic reserves of fat and proteins to cycle the Krebs cycle when undergoing malnutrition or when there is no glucose available for the cells.