Yes, actually it does.
The yeast cells in bread dough ferment sugars and produce gas (carbon dioxide). This makes the dough rise.
When yeast dough rises, the process is called rising or leavening. The first phase of rising, when yeast is dissolved in warm water and sugar until it foams, is called proofing.
The gas produced by yeast during the fermentation process when bread rises is carbon dioxide. As yeast metabolizes sugars, it releases carbon dioxide and alcohol, causing the dough to expand and rise. This gas creates the characteristic airy texture of the bread.
chemical
The gas released by yeast, CO2, creates bubbles, as the bubbles expand in the dough, the bread rises. As the bread bakes, the bubbles set and give the bread its light, airiness.
Because it is. as you know bread is yeast therefore yeast rises to the top and expands leaving the bread bigger than it was. Source: www.eatmypooanddrinkmypee.co.uk
Bread is traditionally made from various products combined with copious amounts of yeast. This concotion is then placed into an oven, and the yeast rises to yield bread.
A chemical change
carbon dioxide
The amount of yeast used in white bread typically ranges from 1 to 2 tablespoons per 4 cups of flour, which is about 0.25 to 0.5 ounces of active dry yeast. This quantity can vary based on the recipe, the type of yeast used, and the desired fermentation time. For instant yeast, a slightly smaller amount may be sufficient, as it is more potent. Adjusting the yeast can also affect the bread's texture and rise.
Bread rises more quickly when it's warm, so it will rise a noticeable amount in just a few minutes in the oven, until it gets hot enough (inside the bread) to kill the yeast, at which point it stops rising.
Yeast is a natural fungus with starts to grow when temperature rises, therefore making bread larger (for example). Yeast is most commonly used in bread making, helping it to rise.