Some yeasts process xylitol and some cannot. The ability to process xylitol is dominant… so what would you cross a xylitol processing yeast with in other to determine if it is heterozygous or homozygous dominant? Solution A xylitol processing yeast will be crossed with another xylitol processing yeast. If they are homozygous dominant all offspring will be xylitol processing but if they are heterozygous dominant then 25% of the offspring will not process xylitol..