What gas do plants absorb from the air during photosynthesis?

What gas do plants absorb from the air during photosynthesis? Plants absorb carbon dioxide from the air during photosynthesis.

Carbon dioxide enters leaves mainly through microscopic pores called stomata. Inside chloroplasts, the enzyme Rubisco helps incorporate its carbon into organic molecules during the Calvin cycle. Light-driven reactions supply ATP and NADPH, which provide the energy and reducing power needed to turn that captured carbon into carbohydrates.

The carbon in plant sugars therefore comes largely from atmospheric carbon dioxide, while the oxygen released by oxygenic photosynthesis comes from water split during the light-dependent reactions. This is why the familiar classroom equation can be misleading if it suggests that released oxygen comes from CO₂.

Plants do not absorb nitrogen gas as their main photosynthetic carbon source, although nitrogen is essential for making proteins and chlorophyll. Argon is chemically inert in this context, and oxygen is generally a product of the light reactions rather than the gas being consumed in the basic photosynthetic process. Joseph Priestley and Jan Ingenhousz helped establish the connection between plants, air, and light in the eighteenth century.