Photosynthesis, Respiration, Transpiration
Plants are self-sufficient. They make their own food thru the process of photosynthesis using light energy to make sugars from carbon dioxide (C02) and water (H20). The three major functions that are basic to plant growth and development are: • Photosynthesis – the process of capturing light energy and converting it to sugar energy, in the presence of chlorophyll using CO2 and H2O, • Respiration – the process of metabolizing (burning) sugars to yield energy for growth, reproduction and other life processes, and • Transpiration – the loss of water vapor through the stomata of leaves. Photosynthesis
A primary difference between plants and animals is the plant’s ability to manufacture its own food. In photosynthesis carbon dioxide from the air and water from the soil react with the sun’s energy to form carbohydrates (sugars and starches). Photosynthesis literally means to put together with light. The photosynthetic process occurs only in the chloroplasts, tiny subcellular structures contained in the cells of leaves and green stems. In photosynthesis, the sun’s energy combines hydrogen from water (H20) with carbon dioxide (CO2) turning them into carbohydrates. Oxygen (O2) is given off as a by-product of photosynthesis. The chemical equation for the process of photosynthesis is: 6CO2 + 6H20 + light C6H12O6 + 6O2 This process is directly dependent on the supply of water, light and carbon dioxide. Any one of the factors on the left side of the equation (carbon dioxide, water, or light) can limit photosynthesis regardless of the availability of the other factors. If any one of these factors is limiting, then the whole process slows down or stops. An implication of drought or severe restrictions on landscape irrigation is a reduction in photosynthesis and thus a decrease in plant vigor. In a tightly closed greenhouse there can be very little fresh air infiltration and CO2 levels can become limiting. This in turn limits plant...
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