The dinoflagellates are a classification subgroup of protista. They are a large group of flagellate eukaryotes. Most are marine plankton, but they are common in freshwater habitats, their populations are distributed depending on salinity, or depth. Many dinoflagellates are known to be photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey. In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although this group is smaller than diatoms; some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, a few forms are parasitic; some dinoflagellates produce resting stages, called dinoflagellate cysts or dinocysts, as part of their lifecycles. Dinoflagellates are considered to be protists, with Dinoflagellata. About 1,555 species of free-living marine dinoflagellates are described. Another estimate suggests about 2,000 living species, of which more than 1,700 are marine and about 220 are from fresh water.
The latest estimates suggest a total of 2,294 living dinoflagellate species, which includes marine and parasitic dinoflagellates. A bloom of certain dinoflagellates can result in a visible coloration of the water colloquially known as red tide, which can cause shellfish poisoning if humans eat contaminated shellfish; some dinoflagellates exhibit bioluminescence—primarily emitting blue-green light. In 1753, the first modern dinoflagellates were described by Henry Baker as "Animalcules which cause the Sparkling Light in Sea Water", named by Otto Friedrich Müller in 1773; the term derives from the Greek word δῖνος, meaning whirling, Latin flagellum, a diminutive term for a whip or scourge. In the 1830s, the German microscopist Christian Gottfried Ehrenberg examined many water and plankton samples and proposed several dinoflagellate genera that are still used today including Peridinium and Dinophysis; these same dinoflagellates were first defined by Otto Bütschli in 1885 as the flagellate order Dinoflagellida.
Botanists treated them as a division of algae, named Pyrrophyta or Pyrrhophyta after the bioluminescent forms, or Dinophyta. At various times, the cryptomonads and ellobiopsids have been included here, but only the last are now considered close relatives. Dinoflagellates have a known ability to transform from noncyst to cyst-forming strategies, which makes recreating their evolutionary history difficult. Dinoflagellates are unicellular and possess two dissimilar flagella arising from the ventral cell side, they have a ribbon-like transverse flagellum with multiple waves that beats to the cell's left, a more conventional one, the longitudinal flagellum, that beats posteriorly. The transverse flagellum is a wavy ribbon in which only the outer edge undulates from base to tip, due to the action of the axoneme which runs along it; the axonemal edge has simple hairs. The flagellar movement produces forward propulsion and a turning force; the longitudinal flagellum is conventional in appearance, with few or no hairs.
It beats with two periods to its wave. The flagella lie in surface grooves: the transverse one in the cingulum and the longitudinal one in the sulcus, although its distal portion projects behind the cell. In dinoflagellate species with desmokont flagellation, the two flagella are differentiated as in dinokonts, but they are not associated with grooves. Dinoflagellates have a complex cell covering called an amphiesma or cortex, composed of a series of membranes, flattened vesicles called alveolae and related structures. In armoured dinoflagellates, these support overlapping cellulose plates to create a sort of armor called the theca, as opposed to athecate dinoflagellates; these occur in various shapes and arrangements, depending on the species and sometimes on the stage of the dinoflagellate. Conventionally, the term tabulation has been used to refer to this arrangement of thecal plates; the plate configuration can be denoted with the plate tabulation formula. Fibrous extrusomes are found in many forms.
Together with various other structural and genetic details, this organization indicates a close relationship between the dinoflagellates, the Apicomplexa, ciliates, collectively referred to as the alveolates. Dinoflagellate tabulations can be grouped into six "tabulation types": gymnodinoid, gonyaulacoid–peridinioid, nannoceratopsioid and prorocentroid; the chloroplasts in most photosynthetic dinoflagellates are bound by three membranes, suggesting they were derived from some ingested algae. Most photosynthetic species contain chlorophylls a and c2, the carotenoid beta-carotene, a group of xanthophylls that appears to be unique to dinoflagellates peridinin and diadinoxanthin; these pigments give many dinoflagellates their typical golden brown color. However, the dinoflagellates Karenia brevis, Karenia mikimotoi, Karlodinium micrum have acquired other pigments through endosymbiosis, including fucoxanthin; this suggests their chloroplasts were incorporated by several endosymbiotic events involving colored or secondarily colorless forms.
The discovery of plastids in the Apicomplexa has led some to suggest they were inherited from an ancestor common to the two groups, b
Microbiology is the study of microorganisms, those being unicellular, multicellular, or acellular. Microbiology encompasses numerous sub-disciplines including virology, parasitology and bacteriology. Eukaryotic microorganisms possess membrane-bound cell organelles and include fungi and protists, whereas prokaryotic organisms—all of which are microorganisms—are conventionally classified as lacking membrane-bound organelles and include Bacteria and Archaea. Microbiologists traditionally relied on culture and microscopy. However, less than 1% of the microorganisms present in common environments can be cultured in isolation using current means. Microbiologists rely on molecular biology tools such as DNA sequence based identification, for example 16s rRNA gene sequence used for bacteria identification. Viruses have been variably classified as organisms, as they have been considered either as simple microorganisms or complex molecules. Prions, never considered as microorganisms, have been investigated by virologists, however, as the clinical effects traced to them were presumed due to chronic viral infections, virologists took search—discovering "infectious proteins".
The existence of microorganisms was predicted many centuries before they were first observed, for example by the Jains in India and by Marcus Terentius Varro in ancient Rome. The first recorded microscope observation was of the fruiting bodies of moulds, by Robert Hooke in 1666, but the Jesuit priest Athanasius Kircher was the first to see microbes, which he mentioned observing in milk and putrid material in 1658. Antonie van Leeuwenhoek is considered a father of microbiology as he observed and experimented with microscopic organisms in 1676, using simple microscopes of his own design. Scientific microbiology developed in the 19th century through the work of Louis Pasteur and in medical microbiology Robert Koch; the existence of microorganisms was hypothesized for many centuries before their actual discovery. The existence of unseen microbiological life was postulated by Jainism, based on Mahavira’s teachings as early as 6th century BCE. Paul Dundas notes that Mahavira asserted the existence of unseen microbiological creatures living in earth, water and fire.
Jain scriptures describe nigodas which are sub-microscopic creatures living in large clusters and having a short life, said to pervade every part of the universe in tissues of plants and flesh of animals. The Roman Marcus Terentius Varro made references to microbes when he warned against locating a homestead in the vicinity of swamps "because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and thereby cause serious diseases."In the golden age of Islamic civilization, Iranian scientists hypothesized the existence of microorganisms, such as Avicenna in his book The Canon of Medicine, Ibn Zuhr who discovered scabies mites, Al-Razi who gave the earliest known description of smallpox in his book The Virtuous Life. In 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or vehicle transmission.
In 1676, Antonie van Leeuwenhoek, who lived most of his life in Delft, observed bacteria and other microorganisms using a single-lens microscope of his own design. He is considered a father of microbiology as he pioneered the use of simple single-lensed microscopes of his own design. While Van Leeuwenhoek is cited as the first to observe microbes, Robert Hooke made his first recorded microscopic observation, of the fruiting bodies of moulds, in 1665, it has, been suggested that a Jesuit priest called Athanasius Kircher was the first to observe microorganisms. Kircher was among the first to design magic lanterns for projection purposes, so he must have been well acquainted with the properties of lenses, he wrote "Concerning the wonderful structure of things in nature, investigated by Microscope" in 1646, stating "who would believe that vinegar and milk abound with an innumerable multitude of worms." He noted that putrid material is full of innumerable creeping animalcules. He published his Scrutinium Pestis in 1658, stating that the disease was caused by microbes, though what he saw was most red or white blood cells rather than the plague agent itself.
The field of bacteriology was founded in the 19th century by Ferdinand Cohn, a botanist whose studies on algae and photosynthetic bacteria led him to describe several bacteria including Bacillus and Beggiatoa. Cohn was the first to formulate a scheme for the taxonomic classification of bacteria, to discover endospores. Louis Pasteur and Robert Koch were contemporaries of Cohn, are considered to be the father of microbiology and medical microbiology, respectively. Pasteur is most famous for his series of experiments designed to disprove the widely held theory of spontaneous generation, thereby solidifying microbiology's identity as a biological science. One of his students, Adrien Certes, is considered the founder of marine microbiology. Pasteur designed methods for food preservation and vaccines against several diseases such as anthrax, fowl cholera and rabies. Koch is best known for his contributions to the germ theory of disease, proving that specific diseases were caused by specific pathogenic microorganisms.
He developed a series of criteria. Koch was one of the first scientists to focus on the i
In food preparation, maceration is softening or breaking into pieces using a liquid. Raw, dried or preserved fruit or vegetables are soaked in a liquid to soften the food and/or absorb the flavor of the liquid into the food. In the case of fresh fruit soft fruit such as strawberries and raspberries, they are just sprinkled with sugar and left to sit and release their own juices; this process makes the food easier to chew and digest. Maceration is confused with marination, the process of soaking foods in a seasoned acidic, liquid before cooking; some herbal preparations call for maceration, as it is one way to extract delicate or volatile herbal essences "cold" and thus preserve their signature more accurately. Sometimes a cooking oil is used as the liquid for maceration – olive or some other vegetable oil. Maceration is the chief means of producing a flavored alcoholic beverage, such as cordials and liqueurs. Maceration of byproducts from food processing plants sometimes involves the use of a chopper pump to create a "blended" slurry of food waste and other organic byproducts.
The macerated substance, which can be described as a protein-rich slurry, is used for animal feed, co-digestion feedstock in biogas plants. Food processor
Petrology is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous and sedimentary petrology. Igneous and metamorphic petrology are taught together because they both contain heavy use of chemistry, chemical methods, phase diagrams. Sedimentary petrology is, on the other hand taught together with stratigraphy because it deals with the processes that form sedimentary rock. Lithology was once synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale description of rocks while petrography is the speciality that deals with microscopic details. In the petroleum industry, lithology, or more mud logging, is the graphic representation of geological formations being drilled through, drawn on a log called a mud log; as the cuttings are circulated out of the borehole they are sampled and tested chemically when needed. Petrology utilizes the fields of mineralogy, optical mineralogy, chemical analysis to describe the composition and texture of rocks.
Petrologists include the principles of geochemistry and geophysics through the study of geochemical trends and cycles and the use of thermodynamic data and experiments in order to better understand the origins of rocks. There are three branches of petrology, corresponding to the three types of rocks: igneous and sedimentary, another dealing with experimental techniques: Igneous petrology focuses on the composition and texture of igneous rocks. Igneous rocks include plutonic rocks. Sedimentary petrology focuses on the texture of sedimentary rocks. Metamorphic petrology focuses on the composition and texture of metamorphic rocks Experimental petrology employs high-pressure, high-temperature apparatus to investigate the geochemistry and phase relations of natural or synthetic materials at elevated pressures and temperatures. Experiments are useful for investigating rocks of the lower crust and upper mantle that survive the journey to the surface in pristine condition, they are one of the prime sources of information about inaccessible rocks such as those in the Earth's lower mantle and in the mantles of the other terrestrial planets and the Moon.
The work of experimental petrologists has laid a foundation on which modern understanding of igneous and metamorphic processes has been built. Important publications in petrology Ore Pedology Atlas of Igneous and metamorphic rocks and textures – Geology Department, University of North Carolina Metamorphic Petrology Database – Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute Petrological Database of the Ocean Floor - Center for International Earth Science Information Network, Columbia University
A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot. Leaves are collectively referred to as foliage, as in "autumn foliage". A leaf is a thin, dorsiventrally flattened organ borne above ground and specialized for photosynthesis. In most leaves, the primary photosynthetic tissue, the palisade mesophyll, is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves have distinct upper surface and lower surface that differ in colour, the number of stomata, the amount and structure of epicuticular wax and other features. Leaves can have many different shapes and textures; the broad, flat leaves with complex venation of flowering plants are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants. In the clubmosses, with different evolutionary origins, the leaves are simple and are known as microphylls.
Some leaves, such as bulb scales, are not above ground. In many aquatic species the leaves are submerged in water. Succulent plants have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls and spines. Furthermore, several kinds of leaf-like structures found in vascular plants are not homologous with them. Examples include flattened plant stems called phylloclades and cladodes, flattened leaf stems called phyllodes which differ from leaves both in their structure and origin; some structures of non-vascular plants function much like leaves. Examples include the phyllids of liverworts. Leaves are the most important organs of most vascular plants. Green plants are autotrophic, meaning that they do not obtain food from other living things but instead create their own food by photosynthesis, they capture the energy in sunlight and use it to make simple sugars, such as glucose and sucrose, from carbon dioxide and water. The sugars are stored as starch, further processed by chemical synthesis into more complex organic molecules such as proteins or cellulose, the basic structural material in plant cell walls, or metabolised by cellular respiration to provide chemical energy to run cellular processes.
The leaves draw water from the ground in the transpiration stream through a vascular conducting system known as xylem and obtain carbon dioxide from the atmosphere by diffusion through openings called stomata in the outer covering layer of the leaf, while leaves are orientated to maximise their exposure to sunlight. Once sugar has been synthesized, it needs to be transported to areas of active growth such as the plant shoots and roots. Vascular plants transport sucrose in a special tissue called the phloem; the phloem and xylem are parallel to each other but the transport of materials is in opposite directions. Within the leaf these vascular systems branch to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to the transportation system. Leaves are broad and thin, thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts, thus promoting photosynthesis.
They are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications. For instance plants adapted to windy conditions may have pendent leaves, such as in many willows and eucalyptss; the flat, or laminar, shape maximises thermal contact with the surrounding air, promoting cooling. Functionally, in addition to carrying out photosynthesis, the leaf is the principal site of transpiration, providing the energy required to draw the transpiration stream up from the roots, guttation. Many gymnosperms have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and frost; these are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. Some leaf forms are adapted to modulate the amount of light they absorb to avoid or mitigate excessive heat, ultraviolet damage, or desiccation, or to sacrifice light-absorption efficiency in favour of protection from herbivory.
For xerophytes the major constraint drought. Some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes. and Bulbine mesembryanthemoides. Leaves function to store chemical energy and water and may become specialised organs serving other functions, such as tendrils of peas and other legumes, the protective spines of cacti and the insect traps in carnivorous plants such as Nepenthes and Sarracenia. Leaves are the fundamental structural units from which cones are constructed in gymnosperms and from which flowers are constructed in flowering plants; the internal organisation of most kinds of leaves has evolved to maximise exposure of the photosynthetic organelles, the chloroplasts, to light and to increase the absorption of carbon dioxide while at the same time controlling water loss. Their surfaces are waterproofed by the plant cuticle and gas exchange between the mesophyll cells and the atmosphere is controlled by minute openings called stomata which open or close to regulate the rate exchange of carbon dioxide and water vapour into
Amber is fossilized tree resin, appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects. Amber is used in jewelry, it has been used as a healing agent in folk medicine. There are five classes of amber, defined on the basis of their chemical constituents; because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions. Amber occurring in coal seams is called resinite, the term ambrite is applied to that found within New Zealand coal seams; the English word amber derives from Arabic ʿanbar عنبر via Middle Latin ambar and Middle French ambre. The word was adopted in Middle English in the 14th century as referring to what is now known as ambergris, a solid waxy substance derived from the sperm whale. In the Romance languages, the sense of the word had come to be extended to Baltic amber from as early as the late 13th century. At first called white or yellow amber, this meaning was adopted in English by the early 15th century.
As the use of ambergris waned, this became the main sense of the word. The two substances conceivably became associated or confused because they both were found washed up on beaches. Ambergris is less dense than water and floats, whereas amber is too dense to float, though less dense than stone; the classical names for amber, Latin electrum and Ancient Greek ἤλεκτρον, are connected to a term ἠλέκτωρ meaning "beaming Sun". According to myth, when Phaëton son of Helios was killed, his mourning sisters became poplar trees, their tears became elektron, amber; the word elektron gave rise to the words electric and their relatives because of amber's ability to bear a static electricity charge. Theophrastus discussed amber in the 4th century BC, as did Pytheas, whose work "On the Ocean" is lost, but was referenced by Pliny the Elder, according to whose The Natural History: Pytheas says that the Gutones, a people of Germany, inhabit the shores of an estuary of the Ocean called Mentonomon, their territory extending a distance of six thousand stadia.
Earlier Pliny says that Pytheas refers to a large island - three days' sail from the Scythian coast and called Balcia by Xenophon of Lampsacus - as Basilia - a name equated with Abalus. Given the presence of amber, the island could have been Heligoland, the shores of Bay of Gdansk, the Sambia Peninsula or the Curonian Lagoon, which were the richest sources of amber in northern Europe, it is assumed that there were well-established trade routes for amber connecting the Baltic with the Mediterranean. Pliny states explicitly that the Germans exported amber to Pannonia, from where the Veneti distributed it onwards; the ancient Italic peoples of southern Italy used to work amber. Amber used in antiquity as at Mycenae and in the prehistory of the Mediterranean comes from deposits of Sicily. Pliny cites the opinion of Nicias, according to whom amberis a liquid produced by the rays of the sun. Besides the fanciful explanations according to which amber is "produced by the Sun", Pliny cites opinions that are well aware of its origin in tree resin, citing the native Latin name of succinum.
In Book 37, section XI of Natural History, Pliny wrote: Amber is produced from a marrow discharged by trees belonging to the pine genus, like gum from the cherry, resin from the ordinary pine. It is a liquid at first, which issues forth in considerable quantities, is hardened Our forefathers, were of opinion that it is the juice of a tree, for this reason gave it the name of "succinum" and one great proof that it is the produce of a tree of the pine genus, is the fact that it emits a pine-like smell when rubbed, that it burns, when ignited, with the odour and appearance of torch-pine wood, he states that amber is found in Egypt and in India, he refers to the electrostatic properties of amber, by saying that "in Syria the women make the whorls of their spindles of this substance, give it the name of harpax from the circumstance that it attracts leaves towards it, the light fringe of tissues". Pliny says that the German name of amber was glæsum, "for which reason the Romans, when Germanicus Caesar commanded the fleet in those parts, gave to one of these islands the name of Glæsaria, which by the barbarians was known as Austeravia".
This is confirmed by the recorded Old High German word glas and by the Old English word glær for "amber". In Middle Low German, amber was known as berne-, barn-, börnstēn; the Low German term became dominant in High Germ