Question

Why flowers chang into fruits

Answer 1

No, ovary change into food as it is the reproductive part.
and ovules change into seed.

Answer 2

When a grain of pollen reaches the stigma, it creates a pollen tube for the sperm to journey down the style and fertilize the ovule; fertilized ovules become seeds. Fertilization is the death of the flower, as the petals drop or wither at this point and the ovary starts to enlarge and ripen intowhat we know as fruit.

Hope its help you