Final answer:
Autotrophs obtain CO2 from the air during photosynthesis, and N2 from the soil through their roots. They use these substances to make their own food.
Step-by-step explanation:
Autotrophs obtain CO2 from the air during photosynthesis. They also obtain N2 from the soil through their roots. Autotrophs use CO2 and N2 to make their own food through the process of photosynthesis, where they convert sunlight into chemical energy and use that energy to combine CO2 and N2 to produce glucose and other organic molecules.