Answer:
production of a gas
Step-by-step explanation:
What makes the cake grow is the action caused by yeast. When added in the dough the yeast undergoes a chemical transformation releasing carbon dioxide, for example from the reaction between sodium bicarbonate and monoacid phosphate. It is the carbon dioxide that makes the cake grow, making the dough light and soft. This reaction is favored by heating, so the use of frozen ingredients in the preparation of the dough can harm the end result.