F.4 Bio bio勁人入黎

In the production of beer, the raw material used is barley grains, which contain a large amount of starch. When barley grains germinate, amylase is produced. The grains are then crushed and mixed with warm water. After several hours, yeast is added to the mixture of fermentation

1.I would want to ask that when barley grains germinate, why amylase is produced??
2.After the crushed grains are mixed with warm water, why is it necessary to wait for several hours before adding the yeast??