AP BIOLOGY

Detailed explanation-1: -Plants release oxygen during the day in the presence of natural light through the process of photosynthesis. While at night, the plants uptake oxygen and release carbon dioxide, which is called respiration.

Detailed explanation-2: -But at night, plants do not uptake CO2 for photosynthesis. Maintaining artificially high levels of CO2 at night may, therefore, be wasteful. Low cost technology is now available to automatically switch on and off the CO2 gas supply during the day and night.

Detailed explanation-3: -During daylight hours, plants take in carbon dioxide and release oxygen through photosynthesis, and at night only about half that carbon is then released through respiration. However, plants still remain a net carbon sink, meaning they absorb more than they emit.

Detailed explanation-4: -These plants do release some oxygen at night when the stomata open and the oxygen can escape. Carbon dioxide is not released during photosynthesis, but small amounts of that gas are emitted both day and night as a by-product of cellular respiration.