At the most basic level of matter conversion resulting in loss of gravity in the beer it must exit as a volatile (gas co2,o2), or be converted into a larger molecule that uses more space than before and increases dissolved volume.

With 10ppm o2 is only 0.001% of the mass. 

When oxygen is taken up by yeast but not part of making ethanol biomass is the byproduct. Biomass is not a factor adding to disolved solution volume, because it settles out as trub. In fact it increases a typical wort solutions specific gravity. Because yeast cell is 70% water. (Harden: note on the water content of the yeast cell pg. 608). Wort would need to have >30% of its mass as not water for this effect not to happen.

In practical brewing, I believe this is the culprit for many skewed readings in attenuation calculations. Not from uptake of sugar that doesn't result in ethanol.

**As for how much sugar is "wasted" and not converted to ethanol. I don't think it's measurable outside of lab conditions and is not a major concern to a homebrewer.**