Autotrophic organisms, such as green plants, use photosynthesis to prepare their own food. This process requires:
- Carbon dioxide (CO$_2$) and water (H$_2$O) as raw materials.
- Sunlight as an energy source.
- Chlorophyll, a green pigment that captures sunlight and helps in the conversion of CO$_2$ and H$_2$O into glucose and oxygen.