Like all batteries, eventually it gets depleted and needs to be replaced; this can be expected to happen after 5-10 years, depending on system usage. CMOS checksum error (and similar messages) or the system clock being reset are classic signs of the battery having been depleted. The BIOS settings contain several system-critical values.
In order to grow, yeast need glucose (C 6 H 12 O 6) or sucrose (table sugar, C 12 H 22 O 11), water (H 2 O) and warm temperatures. As yeast digest sugar, they turn into alcohol. In the process they give off carbon dioxide (CO 2) gas. The alcohol dissolves in the water and the gas escapes into the air. Yeast is used to make bread.
3 +H 2 O+CO 2 Ca(HCO 3) 2. The heat of the oven kills the yeast and burns off the alcohol. You can test for carbon dioxide with limewater. When you feed yeast in the presence of limewater, the calcium in the limewater reacts with carbon dioxide gas from the yeast to form calcium carbonate. Calcium carbonate stays in suspension and creates a milky colour.