What is the process called when certain bacteria use chemical energy to produce carbohydrates?

Chemosynthesis is the process by which certain bacteria and other organisms use chemical energy, typically derived from inorganic molecules, to produce carbohydrates. This process fundamentally differs from photosynthesis, which relies on light energy from the sun to convert carbon dioxide and water into glucose and oxygen. In contrast, chemosynthetic organisms often inhabit extreme environments, such as deep-sea hydrothermal vents, where they harness energy from chemical reactions involving substances like hydrogen sulfide or methane. This ability allows them to synthesize organic compounds without relying on sunlight, thus forming the base of ecosystems in nutrient-poor areas.

Respiration refers to the metabolic processes by which organisms convert food into energy, while fermentation is a specific type of anaerobic respiration that produces energy and various byproducts in the absence of oxygen. Though they contribute to energy production and carbon cycling, neither directly involves the synthesis of carbohydrates through chemical energy, as seen in chemosynthesis.