AP BIOLOGY

Detailed explanation-1: -So, plants take in carbon dioxide from the atmosphere for preparing food. At night, photosynthesis does not occur hence they take in oxygen and give out carbon dioxide. Therefore, it is said that during the daytime, plants take in carbon dioxide and give out oxygen, and during the night it is vice-versa.

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.

Detailed explanation-4: -But during night time, plants perform only respiration and no photosynthesis (since absence of sunlight). Thus concentration of CO2 released is higher during night time.

Detailed explanation-5: -Plants typically absorb CO2 and release oxygen, but they also “exhale” CO2, particularly at night, when photosynthesis ceases due to the lack of sunlight. Forests also emit more CO2 when they are stressed by increasing temperatures.