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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 ...
-autotroph: Photo litho autotroph: Some bacteria (cyanobacteria), some eukaryotes (eukaryotic algae, land plants). Photosynthesis. Breaking Chemical Compounds Chemo-Organic-organo-Organic-heterotroph: Chemo organo heterotroph: Predatory, parasitic, and saprophytic prokaryotes. Some eukaryotes (heterotrophic protists, fungi, animals) Carbon ...
Cornelis Van Niel made key discoveries explaining the chemistry of photosynthesis. By studying purple sulfur bacteria and green bacteria , he was the first to demonstrate that photosynthesis is a light-dependent redox reaction in which hydrogen reduces (donates its atoms as electrons and protons to) carbon dioxide.
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]
Position in the food web, or trophic level, is used in ecology to broadly classify organisms as autotrophs or heterotrophs. This is a non-binary classification; some organisms (such as carnivorous plants) occupy the role of mixotrophs, or autotrophs that additionally obtain organic matter from non-atmospheric sources.
Autotrophic protists that make their own food without needing to consume other organisms, usually by photosynthesis (sometimes by chemosynthesis) Green algae, Pyramimonas: Red and brown algae, diatoms, coccolithophores and some dinoflagellates. Plant-like protists are important components of phytoplankton discussed below. Animal-like
Chloroplasts (from the Greek chloros for green, and plastes for "the one who forms" [31]) are organelles that conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules while freeing oxygen from water in plant and algal cells.