What gas is essential for the process of photosynthesis?

The gas essential for the process of photosynthesis is carbon dioxide. During photosynthesis, plants, algae, and some bacteria convert carbon dioxide from the atmosphere, along with water, into glucose and oxygen, using sunlight as energy. The overall equation for photosynthesis reflects this, where carbon dioxide and water are transformed into glucose and oxygen, highlighting the critical role of carbon dioxide as a carbon source for producing organic molecules.

In contrast, oxygen is a byproduct of photosynthesis rather than a raw material, helium is not utilized by plants in any biological processes, and nitrogen, while important for various plant functions, is primarily involved in the synthesis of amino acids and nucleotides and does not play a direct role in the photosynthetic process itself. Thus, carbon dioxide is fundamental to the creation of energy-rich compounds that sustain plant life and, by extension, life on Earth.