Photosynthesis is a biological process used by many cellular organisms to convert light energy into chemical energy, which is stored in organic compounds that can later be metabolized through cellular respiration to fuel the organism's activities. The term usually refers to oxygenic photosynthesis, where oxygen is produced as a byproduct, and some of the chemical energy produced is stored in carbohydrate molecules such as sugars, starch and cellulose, which are synthesized from endergonic reaction of carbon dioxide with water. Most plants, 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 most of the biological energy necessary for complex life on Earth.
Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type genus Amaranthus. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making it the most species-rich lineage within its parent order, Caryophyllales.
Ribulose-1,5-bisphosphate carboxylase/oxygenase, commonly known by the abbreviations RuBisCo, rubisco, RuBPCase, or RuBPco, is an enzyme involved in light-independent part of photosynthesis, including the carbon fixation by which atmospheric carbon dioxide is converted by plants and other photosynthetic organisms to energy-rich molecules such as glucose. It emerged approximately four billion years ago in primordial metabolism prior to the presence of oxygen on earth. It is probably the most abundant enzyme on Earth. In chemical terms, it catalyzes the carboxylation of ribulose-1,5-bisphosphate.
C4 carbon fixation or the Hatch–Slack pathway is one of three known photosynthetic processes of carbon fixation in plants. It owes the names to the 1960s discovery by Marshall Davidson Hatch and Charles Roger Slack that some plants, when supplied with 14CO2, incorporate the 14C label into four-carbon molecules first.
Photorespiration (also known as the oxidative photosynthetic carbon cycle or C2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis. The desired reaction is the addition of carbon dioxide to RuBP (carboxylation), a key step in the Calvin–Benson cycle, but approximately 25% of reactions by RuBisCO instead add oxygen to RuBP (oxygenation), creating a product that cannot be used within the Calvin–Benson cycle. This process lowers the efficiency of photosynthesis, potentially lowering photosynthetic output by 25% in C3 plants. Photorespiration involves a complex network of enzyme reactions that exchange metabolites between chloroplasts, leaf peroxisomes and mitochondria.
C3 carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being C4 and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosphoglycerate through the following reaction:
The Gomphrenoideae are a subfamily of the Amaranthaceae.
The evolution of plants has resulted in a wide range of complexity, from the earliest algal mats, through multicellular marine and freshwater green algae, terrestrial bryophytes, lycopods and ferns, to the complex gymnosperms and angiosperms of today. While many of the earliest groups continue to thrive, as exemplified by red and green algae in marine environments, more recently derived groups have displaced previously ecologically dominant ones; for example, the ascendance of flowering plants over gymnosperms in terrestrial environments.
Axonopus is a genus of plants in the grass family, known generally as carpet grass. They are native primarily to the tropical and subtropical regions of the Americas with one species in tropical Africa and another on Easter Island. They are sometimes rhizomatous and many are tolerant of periodic submersion.
The BOP clade (sometimes BEP clade) is one of two major lineages (or clades) of undefined taxonomic rank in the grasses (Poaceae), containing more than 5,400 species, about half of all grasses. Its sister group is the PACMAD clade; contrary to many species of that group who have evolved C4 photosynthesis, the BOP grasses all use the C3 photosynthetic pathway.
Alloteropsis semialata, known commonly as black seed grass, cockatoo grass, donkersaad gras, swartsaadgras, tweevingergras, and isi quinti, is a perennial grass distributed across much of tropical and subtropical Africa, Asia and Australia, as well as Papuasia and Madagascar. The genus name Allopteropsis comes from the Greek words "allotrios", meaning "belonging to another", and "opsis", meaning appearance. The specific epithet semialata comes from the Latin "semi" (half) and "ala" (wing), referring to the winged margins of the upper glume.
Oryzoideae (syn. Ehrhartoideae) is a subfamily of the true grass family Poaceae. It has around 120 species in 19 genera, notably including the major cereal crop rice. Within the grasses, this subfamily is one of three belonging to the species-rich BOP clade, which all use C3 photosynthesis; it is the basal lineage of the clade.
The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP clade. The PACMAD lineage is the only group within the grasses in which the C4 photosynthesis pathway has evolved; studies have shown that this happened independently multiple times.
Paniceae is a large tribe of the subfamily Panicoideae in the grasses (Poaceae), the only in the monotypic supertribe Panicodae. It includes roughly 1,500 species in 84 genera, primarily found in tropical and subtropical regions of the world. Paniceae includes species using either of the C4 and C3 photosynthetic pathways, as well as presumably intermediate species. Most of the millets are members of tribe Paniceae.
The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy is used to assemble sugars from carbon dioxide and a hydrogen and electron source such as water. The process of photosynthesis was discovered by Jan Ingenhousz, a Dutch-born British physician and scientist, first publishing about it in 1779.
Cathestecum is a genus of the North American plants in the grass family.
Micrairoideae is a subfamily of the grass family Poaceae, distributed in tropical and subtropical regions. Within the PACMAD clade, it is sister to subfamily Arundinoideae.
Euploca is an almost cosmopolitan genus of plants with around 100 species. It was first described by Thomas Nuttall in 1837. While part of the broadly defined Boraginaceae in the APG IV system from 2016, a revision of the order Boraginales from the same year includes Euploca in the separate family Heliotropiaceae. Its species used to be classified in the genera Hilgeria and Schleidenia and in Heliotropium sect. Orthostachys, but were found to form an independent lineage in a molecular phylogenetic analysis, more closely related to Myriopus than to Heliotropium. While many species use the C4 photosynthetic pathway, there are also C3–C4 intermediate species. Species have leaves with a C4-typical Kranz anatomy.
