Photosynthesis is the process of conversion of light energy (sunlight) into chemical energy (food) by using carbon dioxide, water and chlorophyll, where oxygen is evolved as a by-product.
6 CO2 + 12 H2O → Glucose (C6H12O6) + 6 H2O + 6 O2
Starch (C6H10O5)n is a complex sugar formed on joining of glucose molecules.
The food produced in the leaves are stored in the form of starch as they are insoluble in water and acts as a reserve food supply.
It can be stored in different plant parts like leaves, stems, roots, etc.
Final answer: The food prepared by plants is stored as starch.