Photosynthesis carried out by diatoms comprises about one fifth of the total photosynthesis. Carotenes are photosynthetic pigments important for photosynthesis. Modern photosynthesis in plants and most photosynthetic prokaryotes is oxygenic. In green plants, the carbon dioxide released during respiration gets utilized during photosynthesis. Refer to (cellular respiration, anaerobic respiration and photosynthesis). Plants require magnesium to synthesize chlorophyll, essential for photosynthesis. Water is fundamental to photosynthesis and respiration. Potassium serves as an activator of enzymes used in photosynthesis and respiration. These changes provide a balance of carbon between photosynthesis and respiration. Mature leaves contain chloroplasts that are essential in photosynthesis. It is also used to replace water lost during transpiration and photosynthesis. Organisms capable of assimilating energy by photosynthesis or through inorganic fixation of HS are autotrophs. Phytoplankton manufacture their own food using a process of photosynthesis. Photoautotrophs evolved from heterotrophic bacteria by developing photosynthesis. This nutrient is involved in photosynthesis and plant structure.