How much alcohol the yeast can tolerate depends partly on the type of yeast. And that’s another reason wine is stronger than beer: beer-yeast, with a lower tolerance for alcohol, is killed by the time the alcohol reaches about nine percent. Wine-yeast is hardier and can withstand concentrations up to around sixteen percent. Since most beer is less than six percent alcohol and wine is generally under twelve percent, yeast usually runs out of sugar before it creates enough alcohol to poison itself. Novice home-brewers and wine-makers often try to boost the alcohol content by using a lot of sugar. This works up to a point, but every strain of yeast has a limit to how much alcohol it can produce before quitting. Adding more sugar will make a sweeter beer or wine, but it won’t make it any stronger.