Question

conversion of milk to yoghurt

Answer 1

the bacteria called lactobacillus reproduces in the milk and change the sugar lactose into the lactic acid
due to this conversion curd is formed
hope it will help you

Answer 2

To turn milk into yogurt, these bacteria ferment the milk, turning the lactose sugars in the milk into lactic acid. The lactic acid is what causes the milk, as it ferments, to thicken and taste tart.