Plants exchange gases with their environment, a process that varies significantly with light. Understanding this helps clarify what plants release into the atmosphere, especially in darkness. This article explores the gases plants exchange and specifically answers what they give off at night.
Plants’ Daytime Role: Photosynthesis
During the day, plants engage in photosynthesis to produce their own food. This process occurs primarily in the leaves, where chloroplasts capture light energy. Plants take in carbon dioxide from the atmosphere through tiny pores on their leaves called stomata, and absorb water through their roots. Using light energy, they convert carbon dioxide and water into glucose (a sugar for energy) and release oxygen as a byproduct. Thus, during the day, plants are net producers of oxygen.
Plants at Night: Cellular Respiration and Carbon Dioxide Release
When darkness falls, photosynthesis stops because it requires light, but plants continue cellular respiration. This process occurs continuously in all living cells, including roots and non-green parts. During respiration, plants take in oxygen and break down sugars produced during photosynthesis to release energy. Carbon dioxide is a byproduct of this energy release. Therefore, the gas plants primarily give off in the dark is carbon dioxide.
Why Respiration is Essential for Plants
Cellular respiration is important for a plant’s survival and growth. This process converts stored chemical energy from glucose into a usable form called adenosine triphosphate (ATP). ATP powers all metabolic activities within the plant, such as nutrient uptake, cell division, and substance transport. Even without light for photosynthesis, plants require a constant energy supply to maintain cellular functions and continue growing. Respiration ensures plants sustain life during darkness.
Implications for Our Environment
While plants release carbon dioxide at night, the amount is small and not considered harmful to humans indoors. A single houseplant releases significantly less carbon dioxide than a sleeping human or a pet. Plants are net oxygen producers over a 24-hour cycle, meaning the oxygen they produce during the day through photosynthesis far outweighs the carbon dioxide they release through respiration. Therefore, having plants indoors, even in a bedroom, is safe and can offer benefits like improved air quality and a sense of well-being.