Riesling grapes are naturally very high in acid, and the cool, northern climate of Germany means this ripping acid stays in the grapes even into the fall harvest season. So winemakers let the fermentations stop before the wine is completely dry, retaining a little sweetness in order to strike balance in the wine.
Oxygenation refers to the process of adding oxygen to the body system. There is no way to reliably measure arterial oxygenation via clinical signs alone. Cyanosis, pallor and other physical findings are not reliable.
Energy is obtained more efficiently in the presence of oxygen via the process called aerobic respiration. When there is no oxygen available to break the sugar molecules, some cells are still able to produce energy by the process called fermentation or anaerobic cellular respiration or anaerobic glycolysis. Certain organisms do not need molecular oxygen to produce the energy molecules called ATP.