In the process of photosynthesis it is evident that carbon dioxide, water and light are the reactants while glucose and oxygen are the products. This is equal to respiration but in reverse manner. The other difference in respiration and photosynthesis is that for the photosynthesis solar light is important but for the respiration days and nights are same. In dark the tree leaves instead of photosynthesised, they respire and use oxygen and release carbon dioxide. But what happens at dawn and dusk where light is present but low in intensity? Here oxygen is releases from photosynthesis in low quantity but at the same time respiration also occurs in the leaves and other metabolizing cells of the plant.
For a short time, respiration rate is equal to photosynthetic rate. The oxygen release from the plants at that point just equals the quantity that requires for respiring cells and the carbon dioxide releases by cells just sufficient for the photosynthesizing cells. So, there is no exchange of gasses by the plants with atmosphere. This is termed as compensation point. As the light intensity increases the photosynthetic cells need more carbon dioxide, which respiration only can not fulfil, so, intake of carbon dioxide increases, and gases exchange start to occur.
For a short time, respiration rate is equal to photosynthetic rate. The oxygen release from the plants at that point just equals the quantity that requires for respiring cells and the carbon dioxide releases by cells just sufficient for the photosynthesizing cells. So, there is no exchange of gasses by the plants with atmosphere. This is termed as compensation point. As the light intensity increases the photosynthetic cells need more carbon dioxide, which respiration only can not fulfil, so, intake of carbon dioxide increases, and gases exchange start to occur.
