Photosynthetic in the context of "Biological rhythm"

The Silurian-Devonian Terrestrial Revolution, also known as the Devonian Plant Explosion (DePE) and the Devonian explosion, was a period of rapid colonization, diversification and radiation of land plants (particularly vascular plants) and fungi (especially dikaryans) on dry lands that occurred 428 to 359 million years ago (Mya) during the Silurian and Devonian periods, with the most critical phase occurring during the Late Silurian and Early Devonian.

This diversification of terrestrial photosynthetic florae had vast impacts on the biotic composition of the Earth's surface, especially upon the Earth's atmosphere by oxygenation and carbon fixation. Their roots also eroded into the rocks, creating a layer of water-holding and mineral/organic matter-rich soil on top of Earth's crust known as the pedosphere, and significantly altering the chemistry of Earth's lithosphere and hydrosphere. The floral activities following the Silurian-Devonian plant revolution also exerted significant influences on changes in the water cycle and global climate, as well as driving the biosphere by creating diverse layers of vegetations that provide both sustenance and refuge for both upland and wetland habitats, paving the way for all terrestrial and aquatic biomes that would follow.

Plankton are organisms that drift in water (or air) but are unable to actively propel themselves against currents (or wind). Marine plankton include drifting organisms that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in lakes and rivers. An individual plankton organism in the plankton is called a plankter. In the ocean plankton provide a crucial source of food, particularly for larger filter-feeding animals, such as bivalves, sponges, forage fish and baleen whales.

Plankton includes organisms from species across all the major biological kingdoms, ranging in size from the microscopic (such as bacteria, archaea, protozoa and microscopic algae and fungi) to larger organisms (such as jellyfish and ctenophores). This is because plankton are defined by their ecological niche and level of motility rather than by any phylogenetic or taxonomic classification. The plankton category differentiates organisms from those that can swim against a current, called nekton, and those that live on the deep sea floor, called benthos. Organisms that float on or near the water's surface are called neuston. Neuston that drift as water currents or wind take them, and lack the swimming ability to counter this, form a special subgroup of plankton. Mostly plankton just drift where currents take them, though some, like jellyfish, swim slowly but not fast enough to generally overcome the influence of currents.

The Purple Earth hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin-based chlorophyll, making the surface biosphere appear purplish rather than its current greenish color. It is estimated to have occurred between 3.5 and 2.4 billion years ago during the Archean eon, prior to the Great Oxygenation Event and Huronian glaciation.

Retinal-containing cell membranes exhibit a single light absorption peak centered in the energy-rich green-yellow region of the visible spectrum, but transmit and reflect red and blue light, resulting in a magenta color. Chlorophyll pigments, in contrast, absorb red and blue light, but little or no green light, which results in the characteristic green reflection of plants, cyanobacteria, green algae, and other organisms with chlorophyllic organelles. The simplicity of retinal pigments in comparison to the more complex chlorophyll, their association with isoprenoid lipids in the cell membrane, as well as the discovery of archaeal membrane components in ancient sediments on the Early Earth are consistent with an early appearance of life forms with purple membranes prior to the turquoise of the Canfield ocean and later green photosynthetic organisms.

Paleobotany or palaeobotany, also known as paleophytology, is the branch of botany dealing with the recovery and identification of plant fossils from geological contexts, and their use for the biological reconstruction of past environments (paleogeography), and the evolutionary history of plants, with a bearing upon the evolution of life in general. It is a component of paleontology and paleobiology. The prefix palaeo- or paleo- means "ancient, old", and is derived from the Greek adjective παλαιός, palaios. Paleobotany includes the study of land plants, as well as the study of prehistoric marine photoautotrophs such as photosynthetic algae, seaweeds or kelp. A closely related field is palynology, which is the study of fossilized and extant spores and pollen.

Paleobotany is important in the reconstruction of ancient ecological and climate systems, known as paleoecology and paleoclimatology respectively. It is fundamental to the study of green plant development and evolution. Paleobotany is a historical science much like its adjacent, paleontology. Because of the understanding that paleobotany gives to archeologists, it has become important to the field of archaeology as a whole. primarily for the use of phytoliths in relative dating and in paleoethnobotany.

An apicoplast is a derived non-photosynthetic plastid found in most Apicomplexa, including Toxoplasma gondii, and Plasmodium falciparum and other Plasmodium spp. (parasites causing malaria), but not in others such as Cryptosporidium. It originated from algae through secondary endosymbiosis; there is debate as to whether this was a green or red alga. The apicoplast is surrounded by four membranes within the outermost part of the endomembrane system. The apicoplast hosts important metabolic pathways like fatty acid synthesis, isoprenoid precursor synthesis and parts of the heme biosynthetic pathway.

Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll a. They include other forms of this pigment, such as chlorophyll b in green algal and vascular ("higher") plant antennae, while other algae may contain chlorophyll c or d. In addition, there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins, which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, in particular the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants. The large, physically associated group of chlorophylls and other accessory pigments is sometimes referred to as a pigment bed.

The different chlorophyll and non-chlorophyll pigments associated with the photosystems all have different absorption spectra, either because the spectra of the different chlorophyll pigments are modified by their local protein environment or because the accessory pigments have intrinsic structural differences. The result is that, in vivo, a composite absorption spectrum of all these pigments is broadened and flattened such that a wider range of visible and infrared radiation is absorbed by plants and algae. Most photosynthetic organisms do not absorb green light well, thus most remaining light under leaf canopies in forests or under water with abundant plankton is green, a spectral effect called the "green window". Organisms such as some cyanobacteria and red algae contain accessory phycobiliproteins that absorb green light reaching these habitats.

Phototrophs (from Ancient Greek φῶς, φωτός (phôs, phōtós) 'light' and τροφή (trophḗ) 'nourishment') are organisms that carry out photon capture to acquire energy. They use the energy from light to carry out various cellular metabolic processes. It is a common misconception that phototrophs are obligatorily photosynthetic. Many, but not all, phototrophs photosynthesize: they anabolically convert carbon dioxide into biomolecules to be utilized structurally (e.g. cellulose and membrane lipids), functionally (e.g. vitamins, nucleotides, and amino acids), or as a source for later catabolic processes (e.g. starches, sugars and fats). All phototrophs either use electron transport chains or direct proton pumping to establish an electrochemical gradient, which is utilized by ATP synthase to provide adenosine triphosphate (ATP) for the cell. Phototrophs can be either autotrophs or heterotrophs. If their electron and hydrogen donors are inorganic compounds (e.g., Na
₂S
₂O
₃, as in some purple sulfur bacteria, or H
₂S, as in some green sulfur bacteria) they can be also called lithotrophs, and so, some photoautotrophs are also called photolithoautotrophs. Examples of phototroph organisms are Rhodobacter capsulatus, Chromatium, and Chlorobium.

The silicoflagellates (order Dictyochales) are a small group of unicellular photosynthetic protists, or algae, belonging to the supergroup of eukaryotes known as Stramenopiles. They behave as plankton and are present in oceanic waters. They are well-known from harmful algal blooms that cause high mortality of fish. Additionally, they compose a rich fossil record represented by their silica skeletons.

Casuarina, also known as she-oak, Australian pine and native pine, is a genus of flowering plants in the family Casuarinaceae, and is native to Australia, the Indian subcontinent, Southeast Asia, islands of the western Pacific Ocean, and eastern Africa.

Plants in the genus Casuarina are monoecious or dioecious trees with green, pendulous, photosynthetic branchlets, the leaves reduced to small scales arranged in whorls around the branchlets, the male and female flowers arranged in separate spikes, the fruit a cone containing grey or yellowish-brown winged seeds.

Phycotoxins (from Ancient Greek φῦκος (phûkos) 'seaweed' and τοξικόν (toxikón) 'poison, toxin') are complex allelopathic chemicals produced by eukaryotic and prokaryotic algal secondary metabolic pathways. More simply, these are toxic chemicals synthesized by photosynthetic organisms. These metabolites are (in most cases) not harmful to the producer but may be toxic to either one or many members of the marine food web. This page focuses on phycotoxins produced by marine microalgae; however, freshwater algae and macroalgae are known phycotoxin producers and may exhibit analogous ecological dynamics.In the pelagic marine food web, phytoplankton are subjected to grazing by macro- and micro-zooplankton as well as competition for nutrients with other phytoplankton species. Marine bacteria try to obtain a share of organic carbon by maintaining symbiotic, parasitic, commensal, or predatory interactions with phytoplankton. Other bacteria will degrade dead phytoplankton or consume organic carbon released by viral lysis. The production of toxins is one strategy that phytoplankton use to deal with this broad range of predators, competitors, and parasites. Smetacek suggested that "planktonic evolution is ruled by protection and not competition. The many shapes of plankton reflect defense responses to specific attack systems". Indeed, phytoplankton retain an abundance of mechanical and chemical defense mechanisms including cell walls, spines, chain/colony formation, and toxic chemical production. These morphological and physiological features have been cited as evidence for strong predatory pressure in the marine environment. However, the importance of competition is also demonstrated by the production of phycotoxins that negatively impact other phytoplankton species.Flagellates (especially dinoflagellates) are the principle producers of phycotoxins; however, there are known toxigenic diatoms, cyanobacteria, prymnesiophytes, and raphidophytes. Because many of these allelochemicals are large and energetically expensive to produce, they are synthesized in small quantities. However, phycotoxins are known to accumulate in other organisms and can reach high concentrations during algal blooms. Additionally, as biologically active metabolites, phycotoxins may produce ecological effects at low concentrations. These effects may be subtle, but have the potential to impact the biogeographic distributions of phytoplankton and bloom dynamics.

The purple sulfur bacteria (PSB) are part of a group of Pseudomonadota capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in stratified water environments including hot springs, stagnant water bodies, as well as microbial mats in intertidal zones. Unlike plants, algae, and cyanobacteria, purple sulfur bacteria do not use water as their reducing agent, and therefore do not produce oxygen. Instead, they can use sulfur in the form of sulfide or thiosulfate as the electron donor in their photosynthetic pathways. Some species can use H₂, Fe, or NO₂ as well. The sulfur is oxidized to produce granules of elemental sulfur. This, in turn, may be oxidized to form sulfuric acid.

The purple sulfur bacteria are largely divided into two families, the Chromatiaceae and the Ectothiorhodospiraceae, which produce internal and external sulfur granules respectively, and show differences in the structure of their internal membranes. They make up part of the order Chromatiales, included in the Gammaproteobacteria. The genus Halothiobacillus is also included in the Chromatiales, in its own family, but it is not photosynthetic.

In biology, phototropism, formerly called heliotropism, is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism occurs. This causes the plant to have elongated cells on the furthest side from the light. Phototropism is one of the many plant tropisms, or movements, which respond to external stimuli. Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism. Negative phototropism is not to be confused with skototropism, which is defined as the growth towards darkness, whereas negative phototropism can refer to either the growth away from a light source or towards the darkness. Most plant shoots exhibit positive phototropism, and rearrange their chloroplasts in the leaves to maximize photosynthetic energy and promote growth. Some vine shoot tips exhibit negative phototropism, which allows them to grow towards dark, solid objects and climb them. The combination of phototropism and gravitropism allow plants to grow in the correct direction.

Algae eater or algivore is a common name for any bottom-dwelling or filter-feeding aquatic animal species that specialize in feeding on algae and phytoplanktons. Algae eaters are important for the fishkeeping hobby and many are commonly kept by aquarium hobbyists to improve water quality. They are also important primary consumers that relay the biomass and energy from photosynthetic autotrophes up into the food web, as well as protecting the aquatic ecosystem against algae blooms.

An ecosystem model is an abstract, usually mathematical, representation of an ecological system (ranging in scale from an individual population, to an ecological community, or even an entire biome), which is studied to better understand the real system.

Using data gathered from the field, ecological relationships—such as the relation of sunlight and water availability to photosynthetic rate, or that between predator and prey populations—are derived, and these are combined to form ecosystem models. These model systems are then studied in order to make predictions about the dynamics of the real system. Often, the study of inaccuracies in the model (when compared to empirical observations) will lead to the generation of hypotheses about possible ecological relations that are not yet known or well understood. Models enable researchers to simulate large-scale experiments that would be too costly or unethical to perform on a real ecosystem. They also enable the simulation of ecological processes over very long periods of time (i.e. simulating a process that takes centuries in reality, can be done in a matter of minutes in a computer model).