The only gas given off during photosynthesis is oxygen. In order for photosynthesis to take place, the plant needs carbon dioxide gas, energy from light and water.
Photosynthesis is the process that plants use to transform energy from light into usable energy for common cell operations. The light energy is usually from sunlight, however, certain light bulbs can also be used. The light is absorbed in a pigment called chlorophyll, which then uses water collected from the roots of the plant and carbon dioxide from the air for photosynthesis. The end product is oxygen and adenosine tri-phosphate (ATP), which can be used by all cells for energy.