Question

How come plants produce oxygen even though they need oxygen for respiration?

Answer 1

Hint: Respiration or cellular respiration is a metabolic process that involves the generation of ATP molecules as an energy source. Nutrients that the organism consumed are converted to energy. There are two types of respiration- aerobic and anaerobic. Aerobic respiration, which occurs in the presence of oxygen. Some microorganisms can respire in the absence of oxygen; this type of respiration is called anaerobic respiration.

Complete answer:
Green plants and some microorganisms can synthesize their food. They use carbon dioxide and water to prepare carbohydrates (sugar). This is done in the presence of sunlight. Hence, the process is called photosynthesis. The pigment called chlorophyll, present in the chloroplast (a cell organelle) is required for photosynthesis to take place.
Photosynthesis occurs in two phases, the light-dependent phase, and the light-independent phase. Both occur in different parts of the chloroplast. In the light-dependent phase, the water molecule gets split up to give oxygen. The electrons produced due to this reaction are carried by the electron transport chain and the process continues.
In the light-independent phase finally, sugar is formed. The oxygen that was produced during the light-dependent phase is utilized by the plant for aerobic respiration. Respiration and photosynthesis are opposing processes. During respiration, the plant utilizes the sugar, or its stored starch resource to generateATP molecules. This ATP molecule is its energy source.
Not all of the oxygen produced is utilized by the plant; the remaining oxygen is released into the atmosphere.

Note: Plants respire throughout the day; however photosynthesis occurs only in the presence of sunlight. The byproduct of respiration is carbon dioxide. During the day the plant can use carbon dioxide for photosynthesis. But, that does not happen at night; the plant exhales carbon dioxide. Therefore, it is advisable to not sleep under the trees at night.