Substrate Breakdown and Entry Points Respiratory Pathway Entry Points A. Fats 1. Broken down into glycerol and fatty acids; enters pathway as PGAL or acetyl CoA. B. Fatty Acids 2. Degraded to acetyl CoA and enters the Krebs cycle. C. Proteins 3. Degraded by proteases into amino acids; enters as pyruvate, acetyl CoA, or directly into the Krebs cycle. D. Glycerol 4. Converted into PGAL before entering the glycolytic pa

Step-by-step solution

A - 4: Glycerol is converted into PGAL before entering the glycolytic pathway. B - 2: Fatty acids are degraded to acetyl CoA before entering the Krebs cycle. C - 3: Proteins are degraded into amino acids, which enter the pathway as pyruvate, acetyl CoA, or directly into the Krebs cycle. D - 1: Fats are broken down into glycerol and fatty acids; they enter the respiratory pathway as PGAL or acetyl CoA.