Question

How do autotrophs obtain CO2 & N2 to make their food

Answer 1

Autotrophs like plants takes in co2 from atmosphere as well as obtain from the process of respiration. In plant when there is no photosynthesis in plant during night, then they breathe in o2 and co2 gas is released from the process of respiration. Much of the co2 is released but some are stored. This stored co2 is used during the process of photosynthesis.

Another gas is N2 which the plant obtain it from atmosphere with the help of nitrogen fixing bacteria such as rhizobium in the root nodules of legume family of plants.