Question

what happened to the food that is not needed by plants

Answer 1

The food produced during the photosynthesis process is utilized by the plant.

The food which is not used by the plants is stored for later consumption.

Similarly, the water which is absorbed during the photosynthesis process is stored in the roots as well for later consumption.

The bi lateral product, that is the oxygen is let out by the leaves which is required by us to survive.