Here's a breakdown:

* Autotrophs are organisms that can produce their own food from inorganic sources. They are the base of most food chains.

* Organic nutrients are complex molecules containing carbon, hydrogen, and often oxygen. They are essential for life.

The most common type of autotrophs are photoautotrophs, which use sunlight as their energy source to convert carbon dioxide and water into glucose (a sugar) through photosynthesis. Examples include plants, algae, and some bacteria.

Let me know if you have any other questions!