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Cyanobacteria is the only prokaryotic group that performs oxygenic photosynthesis. Anoxygenic photosynthetic bacteria use PSI- and PSII-like photosystems, which are pigment protein complexes for capturing light. [5] Both of these photosystems use bacteriochlorophyll. There are multiple hypotheses for how oxygenic photosynthesis evolved.
An autotroph is an organism that can convert abiotic sources of energy into energy stored in organic compounds, which can be used by other organisms. Autotrophs produce complex organic compounds (such as carbohydrates , fats , and proteins ) using carbon from simple substances such as carbon dioxide, [ 1 ] generally using energy from light or ...
Photosynthesis usually refers to oxygenic photosynthesis, a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen , cellulose and starches .
Primary nutritional groups are groups of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction. The sources of energy can be light or chemical compounds; the sources of carbon can be of organic or inorganic origin.
Cyanobacteria are globally widespread photosynthetic prokaryotes and are major contributors to global biogeochemical cycles. [25] They are the only oxygenic photosynthetic prokaryotes, and prosper in diverse and extreme habitats. [26] They are among the oldest organisms on Earth with fossil records dating back at least 2.1 billion years. [27]
Cellular respiration is the overall relationship between autotrophs and heterotrophs.Autotrophs are organisms that produce their own food through the process of photosynthesis, whereas heterotrophs are organisms that cannot prepare their own food and depend on autotrophs for nutrition.
Phototrophs can be either autotrophs or heterotrophs. If their electron and hydrogen donors are inorganic compounds (e.g., Na 2 S 2 O 3, as in some purple sulfur bacteria, or H 2 S, as in some green sulfur bacteria) they can be also called lithotrophs, and so, some photoautotrophs are also called photolithoautotrophs.
Diatoms are one of the major photosynthetic producers, and as such produce much of the oxygen that we breathe, and also take in much of the carbon dioxide from the atmosphere. Brown algae, most specifically kelps, create underwater "forest" habitats for many marine creatures, and provide a large portion of the diet of coastal communities.