Final answer:
In stage II of metabolic pathways, the building blocks are further broken down through different reaction pathways to produce ATP and form Acetyl-coenzyme A.
Step-by-step explanation:
In stage II of metabolic pathways, the building blocks are further broken down through different reaction pathways. One of these pathways produces ATP and forms a common end product called Acetyl-coenzyme A, which can then be used in stage III to produce even more ATP.