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.
Basically, each sugar needs to be converted to glucose to enable it to feed into respiration and it is this process which produces the gas which causes the foaming. Yeast is able to synthesise a range of enzymes to do this:-. Sucrose is a disaccharide:- GLUCOSE-FRUCTOSE = SUCROSE. Sucrase will split sucrose.