To enter into the respiratory pathway,protein molecules must be converted into:

Describe the amphibolic pathway.

$A$: The tricarboxylic acid $(TCA)$ cycle is an amphibolic pathway.
$R$: $A$ number of $TCA$ cycle intermediates are used in various catabolic reactions only.

Where is $NADP^+$ reduced to $NADPH$?

When acting as a respiratory substrate,which of the following would be broken down to acetyl Co-$A$?

Given below are two statements:
Statement $I$ - $A$ stepwise release of chemical bond energy facilitates the utilization of a relatively higher proportion of that energy in $ATP$ synthesis.
Statement $II$ - Due to stepwise oxidation of respiratory substrate,the same pathway may be used for synthesis of another biomolecule.
In light of above statements,select the correct answer from the options given below.