What term describes the synthesis of carbohydrates from carbon dioxide and water, limited to certain bacteria and fungi?

The synthesis of carbohydrates from carbon dioxide and water, particularly in certain bacteria and fungi, is known as chemosynthesis. This process is distinct from photosynthesis, which relies on sunlight to convert carbon dioxide and water into glucose and oxygen. In chemosynthesis, organisms use chemical energy obtained from inorganic compounds (such as hydrogen sulfide) instead of sunlight to create organic compounds.

Certain bacteria and archaea, particularly those found in extreme environments like hydrothermal vents, utilize chemosynthesis to produce carbohydrates, supporting unique ecosystems that thrive without sunlight. This process allows these organisms to convert carbon from their inorganic sources into the energy-rich organic compounds they need for growth and reproduction.

In contrast, fermentation and respiration are processes related to breaking down organic substances for energy rather than synthesizing carbohydrates from inorganic sources. Thus, chemosynthesis is the correct term that represents the process described in the question.