Animals carry out active breathing movements to obtain the energy they need for life activities. Through this breathing movement, oxygen is absorbed and carbon dioxide is released.
Like animals, plants do respiration. However, plant respiration is performed through leaf pores, and active breathing movement is not observed.
Plants always respiration during all day and night. However, photosynthesis in plants occurs only when there is sufficient light.
Plants can use carbon dioxide generated by respiration for photosynthesis, and oxygen produced by photosynthesis can be used for respiration.
For example, during the day when there is strong light, it photosynthesizes more than breathing. At this time, plants seem doing only photosynthetic because they absorb carbon dioxide from the pores and release the extra oxygen.
However, at night, plants do not photosynthesize and only respiration, so they absorb oxygen and release carbon dioxide.