Question

Rising of dough is due to:
a. Multiplication of yeast
b. Production of CO2
c. Emulsification
d. Hydrolysis of wheat flour starch into sugars.


NCERT Class XII
Biology - Main Course Book

Chapter 11. Biotechnology: Princeples and Processes

Answer 1

B. The production of Carbon dioxide

In bread making, yeast is added to the dough in order to facilitate the rising of the bread. The yeast cells use the carbohydrates present in flour as an energy source in the process of cellular respiration. In aerobic respiration (respiration in the presence of oxygen), water and carbon dioxide are produced as by-products. In anaerobic respiration (respiration in the absence of oxygen), alcohol and carbon dioxide are produced. It is the carbon dioxide gas which causes the dough to rise. The yeast die due to the alcohol content of the dough and the alcohol evaporates while the bread is baking.  

 

Answer 2

Answer:

a)

Multiplication of yeast