Hint: Living organisms are constantly required to carry out the life processes in order to remain alive. One such life process is excretion in which toxic metabolites are removed out of the body. Many such excretory products of plants are of great importance to human beings.
Complete Answer: Metabolism is defined as the chemical reactions taking place in the body of a living organism. There are many end products of such reactions known as metabolic wastes. There are many metabolic wastes produced in plants through the process of respiration, photosynthesis, etc. - The major excretory products found in plants are carbon dioxide, water due to respiration, nitrogenous compounds due to protein metabolism, and oxygen due to photosynthesis. - This oxygen is very important for human beings as it is required for aerobic respiration which leads to the production of ATP. Without oxygen, no aerobic organism can survive. - Excess water is released from the body through the process of transpiration. By this process, moisture is lost to the atmosphere which helps set out the monsoon cycle. Droughts rarely occur in places with good plant coverage. - Plants also produce some secondary metabolites whose purpose is not fully known in the plants but are very useful to humans. - These secondary metabolites include pigments such as carotenoids and anthocyanins, alkaloids such as morphine and codeine, terpenoids, essential oils such as lemongrass oil, toxins such as abrin and ricin, lectins such as concanavalin A, drugs such as vinblastine curcumin, etc.
Note: - Plants do not have a well-defined excretory system as seen in animals as they do not have such complex toxin that needs to be excreted out. - Transpiration occurs through stomata and lenticels. - Some organic wastes are stored in the bark of the plant instead of being excreted out.