What is the full form of $LAB$?

Statement $P$: Baker's yeast is used to make bread.
Statement $Q$: $LAB$ (Lactic Acid Bacteria) increases the quality of vitamin $B_{12}$.

Milk is converted into curd by . . . . . . .

Besides curdling milk,what other function does $LAB$ (Lactic Acid Bacteria) perform?

Milk is converted into curd $(yoghurt)$ by the biological activity of:

$A$: Cheese is one of the oldest food items in which microbes are used.
$R$: Different varieties of cheese are known by their characteristic texture,flavour,and taste.