On the utilization of carbon sources by autotrophs
Autotrophs can start with inorganic carbon sources and convert them into organic substances through unique biochemical pathways for their own growth and metabolism. This process is of crucial significance in the material cycle and energy conversion of the ecosystem.

The carbon source used by autotrophs is carbon dioxide. It is widely present in the atmosphere and is the main inorganic carbon source available to many autotrophs. Green plants use the delicate mechanism of photosynthesis to use light energy as a driving force in the chloroplast to cause carbon dioxide to react with water. During this process, light energy is captured and converted into chemical energy, which is fixed in organic compounds such as sugars. The reaction formula is roughly as follows: Carbon dioxide and water generate glucose and oxygen under the action of light energy and chloroplast-related enzymes. This not only provides the substances and energy required for plant growth and development, but also lays the foundation for the survival of heterotrophic organisms.

Another type of autotrophic organisms, such as chemoautotrophic bacteria, can use the chemical energy contained in reduced inorganic compounds to drive the fixation of carbon dioxide. For example, nitrifying bacteria, in the soil, obtain energy from ammonia oxide or nitrous acid to synthesize carbon dioxide into organic carbon compounds. Although this process does not rely on light energy, it also uses carbon dioxide as a carbon source to achieve the transition from inorganic carbon to organic carbon.

Autotrophs use carbon sources in different ways, but they can convert simple inorganic carbon sources into complex organic matter. This ability makes autotrophs producers of ecosystems, at the bottom of the food chain, providing material and energy support for the entire ecosystem. And the fixation of carbon sources by autotrophs is also crucial to the global carbon cycle, affecting the concentration of carbon dioxide in the atmosphere, which is closely related to the stability of climate.