Aerobic respiration - HELP!

[KitKat]

I'm doing my A2 coursework on aerobic respiration. I tested 5 sugars: Glucose, Fructose, Galactose, Sucrose and Maltose with a yeast solution. For Galactose, Sucrose and Maltose, they emitted around 4cm3 of Co2 in 3 to 5 minutes. I don't understand how they can emit so much Co2 in such a short space of time and then stop so abruptly. I know it's something to do with disaccharides and the fact that even though galactose is a monosaccharide, it can't respire very well. It just baffles me!!!!!

[mith]

more likely there's too much waste