What are the functions of a plant leaf?

The plant leaf contains chlorophyll which enables the plant to absorb oxygen and complete the photosynthesis process, which is like it's food and nourishment.or something like that :)

Regulating transcription, in mediating immune responses, in regulating cell growth, and in learning and memory.

For photosynthesis the leaf - using chlorophyll - converts the CO2 and sunlight into glucose and oxygen.

the leaf will store and give food to the plant cell