Question

why yeast is added to the batter used to me dosas

Answer 1

Yeast when added to batter undergoes anaerobic respiration whose end products are energy,carbondioxide and alcohol. The carbon dioxide produced makes the batter rise .And the alcohol produced gives it a sour taste which makes dosa batter better.

Answer 2

hey mate....
here is your answer......

yeast is added to make better dosa because it reproduce very rapidly by
fragmentation
budding
fission
and it also release co2 that make the dough of dosa fluffy and tasty.

hope it helps......