The necessary starting ingredient for autotrophs energy pathway is sunlight for photo autotrops and chemical energy for oxidation of inorganic chemicals for chemo autotrops.
Step-by-step explanation:
The autotrophs are the ones using sunlight as the primary source to gain energy and nutrition by using photosynthesis mechanism. Sometimes chemical energy can also be used to oxidate the glucose into sucrose.
Even sunlight is used to convert the glucose into energy by photosynthesis process. The autotrophs which uses sunlight as the main source for creating nutrition is termed as photo autotrophs. The autotrophs which used chemical energy for getting energy is termed as chemo autotrophs.