Answer:
Water
Explanation:
Molecular oxygen is the terminal electron acceptor and serves to receive electrons from reduced NADH and FADH2 to reoxidize them. NADH and FADH2 are formed during glycolysis and Kreb's cycle. These reducing powers should be re-oxidized to enter in the first two steps of aerobic respiration again.
For the purpose, NADH, and FADH2 transfer their electrons to the molecular oxygen via electron transport chain. After accepting the electrons, molecular oxygen is oxidized into the water molecule. Therefore, radioactive oxygen isotope would appear in the form of a water molecule after completion of cellular respiration.

The nephron loops of the juxtamedullary nephrons are surrounded by a looping, ladder-like blood vessel called the

The nephron loops of the juxtamedullary nephrons are surrounded by a looping, ladder-like blood vessel called the Peritubular Capillary network
This network is formed by the Efferent artiole to absorb the non waste martial which is flown out in the ultrafiltration of Glomerular capsule .