1 Most cases of COPD, and therefore emphysema, are caused by cigarette smoking. 2  Emphysema is rarely caused by a congenital condition known as Î±1-antitrypsin deficiency, for which there is a lab test. 3  Shortness of breath and cough are the main symptoms of emphysema.
Most plants, most algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies all of the organic compounds and most of the energy necessary for life on Earth.
Supplement. In order to capture light as source of energy, photoautotrophs carry out photosynthesis, converting energy from sunlight, carbon dioxide and water into organic materials. Photoautotrophs provide nutrition for many forms of life. They include the plants, algae and certain protists bacteria.