Any living organism must be able to excrete wastes or the build up of those materials could be harmful or deadly. Wastes form as a result of metabolic activities--the sum total of all chemical reactions that occur in the body of an organism. Plants are alive and must remove metabolic wastes or they would die.
Plants produce the wastes carbon dioxide and water due to aerobic cellular respiration.Their leaves contain stomates which allow...
Any living organism must be able to excrete wastes or the build up of those materials could be harmful or deadly. Wastes form as a result of metabolic activities--the sum total of all chemical reactions that occur in the body of an organism. Plants are alive and must remove metabolic wastes or they would die.
Plants produce the wastes carbon dioxide and water due to aerobic cellular respiration. Their leaves contain stomates which allow the diffusion of wastes out of the plant and into the environment. Some of the water vapor is excreted by the stomates in a process called transpiration. Some of the water can be reused as a reactant during the light reaction of photosynthesis. Also, the carbon dioxide can be reused as a starting material for the light independent reaction (Calvin Cycle) during photosynthesis to be fixed as an organic compound--ultimately a sugar called G3P. This sugar can be used to build more complex carbohydrates or other organic compounds needed by the plant.
During photosynthesis, carbon dioxide and water combine within the leaf cells, and with the addition of light, produce the products sugar, oxygen and ATP. The oxygen is a waste product. The G3P plants produce during photosynthesis can be used in the synthesis of glucose. The glucose can later be used as a fuel by the plant during respiration as a chemical energy source used to generate ATP. However, the waste product oxygen will be released and excreted into the environment as it exits the plant's stomates.
Plants can also use their root systems to remove metabolic wastes and excrete these into the soil. Some waste products can be stored in vacuoles, or in special cells in stems, leaves or barks. Plants also have lenticels which can allow the removal of wastes through tiny openings in the stem by the process of diffusion. In a cross section of a woody stem, some parts contain older, dead cells which is another area for waste storage known as the heart wood. Saps containing wastes can sometimes be released through various parts of the plant including its leaves.
I have included a link to a power point illustrating methods of waste removal in plants.
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