Part 1: Autotrophs
Organisms that are capable of preparing their own food are called autotrophs. Example - green plants
Part 2: Photosynthesis
Most of the green plants utilise the energy from the sun to convert carbon dioxide and water to glucose, oxygen and water. This process is called photosynthesis. Glucose is the food for the plants. Thus plants are autotrophs that obtain their food by the process called photosynthesis