Which of the following is not an Amphibolic pathway?
Electron transport system
Calvin cycle
TCA cycle
Both a and b
The Electron Transport System (ETS) is the one of the non-amphibolic pathway mentioned above. The ETS is completely catabolic in nature because it results in the oxidative phosphorylation that produces ATP, and the byproducts of this process are water and carbon dioxide, which cannot be used for producing any biomolecules.
Acetyl CoA enters the TCA cycle, where it releases carbon dioxide. This is a catabolic process, however acetyl CoA can also be employed in the anabolic pathway for the production of fatty acids. Consequently, the TCA cycle is an amphibolic pathway.
The Calvin cycle is an anabolic path since it only requires the production of glucose from carbon dioxide during photosynthesis. As a result, the Calvin cycle isn't an amphibolic route.
Option d is the correct answer.