Final answer:
Fat must be broken down into fatty acyl CoA and then into acetyl CoA through fatty acid oxidation before it can enter the Krebs cycle for energy production.
Step-by-step explanation:
The two extra steps that must occur before "fat" can enter the Krebs cycle involve the breakdown of fatty acids through a process known as fatty acid oxidation or beta-oxidation.
Firstly, fatty acids are converted into fatty acyl CoA molecules in the cytoplasm.
These fatty acyl CoA then combine with carnitine to form fatty acyl carnitine, which helps transport the fatty acid across the mitochondrial membrane.
Once inside the mitochondrial matrix, the fatty acyl carnitine is converted back into fatty acyl CoA.
This is then transformed into acetyl CoA, which can enter the Krebs cycle.
From here, the acetyl CoA participates in the citric acid cycle to ultimately produce ATP, as well as reduced coenzymes NADH and FADH2 that enter the electron transport chain for further energy production.