Plants "breathe" by exchanging gases (oxygen and carbon dioxide) through tiny pores called stomata on their leaves. They take in carbon dioxide from the air for photosynthesis (using sunlight to make food) and release oxygen as a waste product during the day. At the same time, they also take in oxygen for respiration (breaking down food for energy) and release carbon dioxide as a waste product. This gas exchange happens by diffusion, where gases move from higher to lower concentration. At night, when photosynthesis stops due to lack of sunlight, plants mainly respire, taking in oxygen and releasing carbon dioxide. Roots also breathe by absorbing oxygen from air spaces in the soil through root hairs. Stomata regulate this process while minimizing water loss by closing when the soil is dry.
In summary, plants breathe in carbon dioxide and breathe out oxygen during the day (photosynthesis dominant), and breathe in oxygen and breathe out carbon dioxide at night (respiration dominant) through stomata on leaves and lenticels on woody stems, with roots absorbing oxygen from soil air spaces.
