What gases do plants take in and give off during photosynthesis?

During photosynthesis, plants primarily take in carbon dioxide and give off oxygen. This process occurs in the chloroplasts of plant cells where chlorophyll captures sunlight, which is then used to convert carbon dioxide and water into glucose and oxygen. The carbon dioxide needed for photosynthesis is absorbed from the atmosphere through small openings on the leaves called stomata.

The oxygen produced is a byproduct of this reaction and is released back into the atmosphere, which is critical for the survival of aerobic organisms that depend on oxygen. This function of plants plays an essential role in maintaining atmospheric balance, making them vital for supporting life on Earth.

The other combinations listed do not accurately represent the gases involved in photosynthesis. Nitrogen, while an essential nutrient for plants in other contexts, is not directly involved in this process, nor is methane—an organic gas not produced by photosynthesis. Therefore, the accurate association of carbon dioxide intake and oxygen output confirms the correct choice.