It is a respiratory irritant and a factor in the creation of smog. Paleobotanical characteristics Paleobotany is the study of early, ancient, or primitive plants. Scientists can study ancient plants by observing fossils of those plants or by examining residue left by the plant's decomposition. Photosynthesis Photosynthesis is a complex chemical process that is unique to green plants. Chlorophyll-containing cells in green plants convert light to chemical energy and synthesize carbohydrates from carbon dioxide and water.
Plants release oxygen during photosynthesis.
The pressure which water exerts equally in all directions increases with increasing depth. The rate of change in the water pressure is a pressure gradient. Pressure gradients in ocean water contribute to the formation of ocean currents. The less pressurized surface water is moved by winds over the more pressurized deeper water. Other factors that contribute to ocean currents are water temperature and density.