Answer:
The growing yeast gives off carbon dioxide gas.
Explanation:
Ancient Egypt first use this idea of growing yeast.
Growing yeast like to eat sugar,starch.
When they eat these food materials,they release a gas called carbon dioxide gas which gradually forms lots of tiny bubbles.
Using this idea, bread is made.As it form tinny bubbles in the bread dough,it pop during the time of baking and leaving tiny holes.
So for their growth and development,water and sugar is an important factor.
