in cellular respiration, how does the hydrogen necessary in the electron transport chain come from the splitting of carbon dioxide molecules and why is this necessary? also does FADH or NADH2 come into play somewhere here?

Urgent. the table shows the relative blood flow through some organs in the human body that is, the percentage of blood that flows through a given organ, through which organ(s) does all the blood flow? explain the effect of exercise on blood flow to skeletal muscles.