Question

Why do leaves fall down from tree when they turn into yellow ?

Answer 1

Because the yellow leaves does not have more amount of chlorophyll . slowly this chlorophyll is reduced and leaf turns into yellowish . As it was not used for preparation of food slowly it falls down.
MARK AS BRAINLINEST IF IT IS HELPFULL

Answer 2

Yellow colors that were always present in leaves become unmasked as the chlorophyll is broken down and absorbed.