Dr. Hodges notes that David's exhaled carbon dioxide levels are elevated. List all the metabolic pathways that function to synthesize ATP for skeletal muscle contraction. Which of these pathways produces carbon dioxide as a by-product?

Explanation:

The production of ATPs for skeletal muscle contraction  depends on the conditions that the muscles are exposed to.

In presence of abundant oxygen, to the cells  Aerobic respiration-cellular respiration is the most ideal. 32 ATPs and 4 C02 are produced as by-products during the process as by products majorly two C02 from each  of the 2 acetyl Co A that enters the  kerb's cycle.

Likewise direct phosphoryaltion of ADP to ATP gives 32.0 kj/mol of heat liberated but no C02 was produced. This takes place during chemiosmosis. with 28ATPs produced.

In absence of oxygen, anaerobic respiration of skeletal muscles produced ATPs  from  glycolysis, heat and  2C02 as products, but not as by-product.Through alcoholic fermentation pathway.

Therefore ,the correct answer is Aerobic respiration, because it gives out C02 which is a by-product, released out of the body as waste from the lungs,and not use up  in  the body.