1.
Taxonomy (biology)
–
Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
Taxonomy (biology)
–
Title page of
Systema Naturae, Leiden, 1735
Taxonomy (biology)
–
Evolution of the
vertebrates at class level, width of spindles indicating number of families. Spindle diagrams are typical for
Evolutionary taxonomy
Taxonomy (biology)
–
The same relationship, expressed as a
cladogram typical for
cladistics
Taxonomy (biology)
–
Type specimen for
Nepenthes smilesii, a tropical
pitcher plant.
2.
Plantae
–
Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. The term is generally limited to the green plants, which form an unranked clade Viridiplantae. This includes the plants, conifers and other gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts and their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic and have lost the ability to produce amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although reproduction is also common. There are about 300–315 thousand species of plants, of which the great majority, green plants provide most of the worlds molecular oxygen and are the basis of most of Earths ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food. Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts. When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae. Each of these groups also includes various microscopic and single-celled organisms
Plantae
–
Green algae from
Ernst Haeckel 's
Kunstformen der Natur, 1904.
Plantae
–
Had'n
Plantae
–
Dicksonia antarctica, a species of
tree fern
Plantae
–
A petrified log in
Petrified Forest National Park.
3.
Angiosperms
–
The flowering plants, also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 416 families, approx. 13,164 known genera and a total of c.295,383 known species, etymologically, angiosperm means a plant that produces seeds within an enclosure, in other words, a fruiting plant. The term angiosperm comes from the Greek composite word meaning enclosed seeds, the ancestors of flowering plants diverged from gymnosperms in the Triassic Period, during the range 245 to 202 million years ago, and the first flowering plants are known from 160 mya. They diversified extensively during the Lower Cretaceous, became widespread by 120 mya, angiosperms differ from other seed plants in several ways, described in the table. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, the amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms. The vascular bundles of the stem are arranged such that the xylem and phloem form concentric rings, in the dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium, the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Among the monocotyledons, the bundles are more numerous in the stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases, the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species, the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf, occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. There are two kinds of cells produced by flowers. Microspores, which divide to become pollen grains, are the male cells and are borne in the stamens. The female cells called megaspores, which divide to become the egg cell, are contained in the ovule. The flower may consist only of parts, as in willow. Usually, other structures are present and serve to protect the sporophylls, the individual members of these surrounding structures are known as sepals and petals. The outer series is usually green and leaf-like, and functions to protect the rest of the flower, the inner series is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators, attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower
Angiosperms
Angiosperms
–
Bud of a pink
rose
Angiosperms
–
Flowers of
Malus sylvestris (crab apple)
Angiosperms
–
Flowers and leaves of
Oxalis pes-caprae (Bermuda buttercup)
4.
Eudicots
–
The eudicots, Eudicotidae or eudicotyledons are a monophyletic clade of flowering plants that had been called tricolpates or non-magnoliid dicots by previous authors. The close relationships among flowering plants with tricolpate pollen grains was initially seen in studies of shared derived characters. These plants have a trait in their pollen grains of exhibiting three colpi or grooves paralleling the polar axis. Later molecular evidence confirmed the basis for the evolutionary relationships among flowering plants with tricolpate pollen grains. The term means true dicotyledons, as it contains the majority of plants that have been considered dicots and have characteristics of the dicots, the term eudicots has subsequently been widely adopted in botany to refer to one of the two largest clades of angiosperms, monocots being the other. The remaining angiosperms are sometimes referred to as basal angiosperms or paleodicots, the other name for the eudicots is tricolpates, a name which refers to the grooved structure of the pollen. Members of the group have tricolpate pollen, or forms derived from it and these pollens have three or more pores set in furrows called colpi. In contrast, most of the seed plants produce monosulcate pollen. The name tricolpates is preferred by some botanists to avoid confusion with the dicots, numerous familiar plants are eudicots, including many common food plants, trees, and ornamentals. Most leafy trees of midlatitudes also belong to eudicots, with exceptions being magnolias and tulip trees which belong to magnoliids, and Ginkgo biloba. The name eudicots is used in the APG system, of 1998 and it is applied to a clade, a monophyletic group, which includes most of the dicots. The eudicots can be divided into two groups, the basal eudicots and the core eudicots, basal eudicot is an informal name for a paraphyletic group. The core eudicots are a monophyletic group, a 2010 study suggested the core eudicots can be divided into two clades, Gunnerales and a clade called Pentapetalae, comprising all the remaining core eudicots
Eudicots
–
Eudicots Temporal range:
Early Cretaceous - recent
Eudicots
–
Arabis pollen has three colpi.
5.
Brassicales
–
The Brassicales are an order of flowering plants, belonging to the eurosids II group of dicotyledons under the APG II system. One character common to members of the order is the production of glucosinolate compounds. Most systems of classification have included this order, although sometimes under the name Capparales, the only families included were the Brassicaceae and Capparaceae, the Tovariaceae, Resedaceae, and Moringaceae. Other taxa now included here were placed in other orders. The families Capparaceae and Brassicaceae are closely related, one group, consisting of Cleome and related genera, was traditionally included in the Capparaceae but doing so results in a paraphyletic Capparaceae. Therefore, this group is now either included in the Brassicaceae or as its own family. Media related to Brassicales at Wikimedia Commons
Brassicales
–
Brassicales
Brassicales
–
Cleome hassleriana
6.
Brassicaceae
–
Brassicaceae or Cruciferae is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. The name Brassicaceae is derived from the included genus Brassica, the alternative older name, Cruciferae, meaning cross-bearing, describes the four petals of mustard flowers, which resemble a cross. Cruciferae is one of eight plant family names without the suffix -aceae that are authorized alternative names, the family contains 372 genera and 4060 accepted species. The largest genera are Draba, Erysimum, Lepidium, Cardamine, pieris rapae and other butterflies of the family Pieridae are some of the best-known pests of Brassicaceae species planted as commercial crops. The family is included in the Brassicales according to the APG system, older systems placed them into the Capparales, a now-defunct order that had a similar definition. This family comprises about 375 genera and 2500 species all over the world,94 species of 38 genera are found in Nepal, a close relationship has long been acknowledged between the Brassicaceae and the caper family, Capparaceae, in part because members of both groups produce glucosinolate compounds. The APG II system, therefore, has merged the two families under the name Brassicaceae, the APG III system has recently adopted this last solution, but this may change as a consensus arises on this point. This article deals with Brassicaceae sensu stricto, i. e. treating the Cleomaceae and Capparaceae as segregated families, the family consists mostly of herbaceous plants with annual, biennial, or perennial lifespans. The leaves are alternate, sometimes organized in basal rosettes, in rare shrubby crucifers of Mediterranean their leaves are mostly in terminal rosettes and they are very often pinnately incised and do not have stipules. The structure of the flowers is extremely uniform throughout the family and they have four free saccate sepals and four clawed free petals, staggered. They can be disymmetric or slightly zygomorphic, with a typical cross-like arrangement and they have six stamens, four of which are longer and are arranged in a cross like the petals and the other two are shorter. The pistil is made up of two fused carpels and the style is short, with two lobes. The flowers form ebracteate racemose inflorescences, often apically corymb-like, pollination occurs by entomogamy, nectar is produced at the base of the stamens and stored on the sepals. The fruit is a kind of capsule named siliqua. It opens by two valves, which are the modified carpels, leaving the attached to a framework made up of the placenta. Often, an indehiscent beak occurs at the top of the style, where a siliqua is less than three times as long as it is broad, it is usually termed a silicula. The siliqua may break apart at constrictions occurring between the segments of the seeds, thus forming a sort of loment, it may eject the seeds explosively or may be evolved in a sort of samara. The fruit is often the most important diagnostic character for plants in this family, most members share a suite of glucosinolate compounds that have a typical pungent odour usually associated with cole crops
Brassicaceae
–
Brassicaceae
Brassicaceae
–
Aubrieta deltoidea (commonly known as purple rock cress) is a perennial wild flower that is used in gardening for its ornamental large inflorescence.
Brassicaceae
–
Siliquae of
Cardamine impatiens
Brassicaceae
–
Lunaria annua with ripe seed pods
7.
Arabidopsis
–
Arabidopsis is a genus in the family Brassicaceae. They are small flowering plants related to cabbage and mustard and this genus is of great interest since it contains thale cress, one of the model organisms used for studying plant biology and the first plant to have its entire genome sequenced. Changes in thale cress are easily observed, making it a useful model. Currently, the genus Arabidopsis has nine species and a further eight subspecies recognised and this delimitation is quite recent and is based on morphological and molecular phylogenies by OKane and Al-Shehbaz and others. Their findings confirm the species included in Arabidopsis made it polyphyletic. All of the species in Arabidopsis are indigenous to Europe, while two of the species have broad ranges also extending into North America and Asia. In the last two decades, Arabidopsis thaliana has gained much interest from the community as a model organism for research on numerous aspects of plant biology. The ordering system for ABRC was incorporated into The Arabidopsis Information Resource database in June 2001 whilst NASC has always hosted its own ordering system and genome browser. In 1982, the crew of the Soviet Salyut 7 space station grew some Arabidopsis, thus becoming the first plants to flower and they had a life span of 40 days. Recently, A. thaliana tissues have been cultivated in microfluidic devices, plant-on-chip devices show promise for future research in understanding the mechanism of sexual reproduction in A. thaliana. Murray & S. I. Warwick Distribution, Greenland, Labrador, Nunavut, Québec, Ontario, Manitoba, Saskatchewan Arabidopsis arenosa Lawalrée, borbasii Distribution, E Belgium, Czech Republic, NE France, Germany, Hungary, Poland, Romania, Slovakia, Switzerland, Ukraine. Halleri Distribution, Austria, Croatia, Czech Republic, Germany, N and C Italy, Poland, Romania, Slovakia, Slovenia, Switzerland, probably introduced in N France and extinct in Belgium. Ovirensis Distribution, Albania, Austria, NE Italy, Romania, Slovakia, Slovenia, SW Ukraine, gemmifera Distribution, Russian Far East, northeastern China, Korea, Japan, and Taiwan. Arabidopsis lyrata OKane & Al-Shehbaz A. lyrata subsp, lyrata Distribution, NE European Russia, Alaska, Canada, and southeastern and central United States. Petraea OKane & Al-Shehbaz Distribution, Austria, Czech Republic, England, Germany, Hungary, Iceland, Ireland, N. Italy, Norway, Russia, Scotland, Sweden, Ukraine, boreal North America. Kamchatica OKane & Al-Shehbaz Distribution, boreal Alaska, Canada, Aleutian Islands, eastern Siberia, the Russian Far East, Korea, northern China, Japan, Arabidopsis pedemontana Distribution, northwestern Italy and, presumably extinct, in adjacent SW Switzerland. Distribution, Fennoscandinavia and the Baltic region, Distribution, native range almost all Europe to central Asia, now naturalized worldwide. Cytogenetic analysis has shown the haploid number is variable and can be 5,8 and 13
Arabidopsis
–
Arabidopsis
8.
Binomial nomenclature
–
Such a name is called a binomial name, a binomen, binominal name or a scientific name, more informally it is also called a Latin name. The first part of the name identifies the genus to which the species belongs, for example, humans belong to the genus Homo and within this genus to the species Homo sapiens. The formal introduction of system of naming species is credited to Carl Linnaeus. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus. Although the general principles underlying binomial nomenclature are common to these two codes, there are differences, both in the terminology they use and in their precise rules. Similarly, both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a name is usually given, at least when it is first mentioned. In zoology Patella vulgata Linnaeus,1758, the original name given by Linnaeus was Fringilla domestica, the parentheses indicate that the species is now considered to belong in a different genus. The ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, in botany Amaranthus retroflexus L. – L. is the standard abbreviation used in botany for Linnaeus. – Linnaeus first named this bluebell species Scilla italica, Rothmaler transferred it to the genus Hyacinthoides, the ICN does not require that the dates of either publication be specified. Prior to the adoption of the binomial system of naming species. Together they formed a system of polynomial nomenclature and these names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description, such polynomial names may sometimes look like binomials, but are significantly different. For example, Gerards herbal describes various kinds of spiderwort, The first is called Phalangium ramosum, Branched Spiderwort, is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia. The Latin phrases are short descriptions, rather than identifying labels, the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné. It was in his 1753 Species Plantarum that he first began using a one-word trivial name together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as an epithet or specific name
Binomial nomenclature
–
Carl Linnaeus (1707–1778), a Swedish botanist, invented the modern system of binomial nomenclature.
9.
Carl Linnaeus
–
Carl Linnaeus, also known after his ennoblement as Carl von Linné, was a Swedish botanist, physician, and zoologist, who formalised the modern system of naming organisms called binomial nomenclature. He is known by the father of modern taxonomy. Many of his writings were in Latin, and his name is rendered in Latin as Carolus Linnæus, Linnaeus was born in the countryside of Småland, in southern Sweden. He received most of his education at Uppsala University. He lived abroad between 1735 and 1738, where he studied and also published a first edition of his Systema Naturae in the Netherlands and he then returned to Sweden, where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on journeys through Sweden to find and classify plants. In the 1750s and 1760s, he continued to collect and classify animals, plants, and minerals, at the time of his death, he was one of the most acclaimed scientists in Europe. The philosopher Jean-Jacques Rousseau sent him the message, Tell him I know no man on earth. The German writer Johann Wolfgang von Goethe wrote, With the exception of Shakespeare and Spinoza, Swedish author August Strindberg wrote, Linnaeus was in reality a poet who happened to become a naturalist. Among other compliments, Linnaeus has been called Princeps botanicorum, The Pliny of the North and he is also considered as one of the founders of modern ecology. In botany, the abbreviation used to indicate Linnaeus as the authority for species names is L. In older publications, sometimes the abbreviation Linn. is found, Linnæus was born in the village of Råshult in Småland, Sweden, on 23 May 1707. He was the first child of Nicolaus Ingemarsson and Christina Brodersonia and his siblings were Anna Maria Linnæa, Sofia Juliana Linnæa, Samuel Linnæus, and Emerentia Linnæa. One of a line of peasants and priests, Nils was an amateur botanist, a Lutheran minister. Christina was the daughter of the rector of Stenbrohult, Samuel Brodersonius, a year after Linnæus birth, his grandfather Samuel Brodersonius died, and his father Nils became the rector of Stenbrohult. The family moved into the rectory from the curates house, even in his early years, Linnæus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which calmed him. Nils spent much time in his garden and often showed flowers to Linnaeus, soon Linnæus was given his own patch of earth where he could grow plants
Carl Linnaeus
–
Carl von Linné,
Alexander Roslin, 1775. Oil painting in the portrait collection at
Gripsholm Castle
Carl Linnaeus
–
The
coat of arms of Carl von Linné.
Carl Linnaeus
–
Birthplace of Linnæus at
Råshult
Carl Linnaeus
–
Statue of Linnaeus as a University student in
Lund
10.
Synonym (taxonomy)
–
For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies. This name is no longer in use, it is now a synonym of the current scientific name which is Picea abies, unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms are not equals, but have a different status, for any taxon with a particular circumscription, position, and rank, only one scientific name is considered to be the correct one at any given time. A synonym cannot exist in isolation, it is always an alternative to a different scientific name, given that the correct name of a taxon depends on the taxonomic viewpoint used a name that is one taxonomists synonym may be another taxonomists correct name. Synonyms may arise whenever the same taxon is described and named more than once, independently. They may also arise when existing taxa are changed, as when two taxa are joined to one, a species is moved to a different genus. To the general user of scientific names, in such as agriculture, horticulture, ecology, general science. A synonym is a name that was used as the correct scientific name but which has been displaced by another scientific name. Thus Oxford Dictionaries Online defines the term as a name which has the same application as another. In handbooks and general texts, it is useful to have mentioned as such after the current scientific name. Synonyms used in this way may not always meet the strict definitions of the synonym in the formal rules of nomenclature which govern scientific names. Changes of scientific name have two causes, they may be taxonomic or nomenclatural, a name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight. A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature, the earliest such name is called the senior synonym, while the later name is the junior synonym. One basic principle of zoological nomenclature is that the earliest correctly published name, synonyms are important because if the earliest name cannot be used, then the next available junior synonym must be used for the taxon. Objective synonyms refer to taxa with the type and same rank. For example, John Edward Gray published the name Antilocapra anteflexa in 1855 for a species of pronghorn, however, it is now commonly accepted that his specimen was an unusual individual of the species Antilocapra americana published by George Ord in 1815. Ords name thus takes precedence, with Antilocapra anteflexa being a subjective synonym. Objective synonyms are common at the level of genera, because for various reasons two genera may contain the type species, these are objective synonyms
Synonym (taxonomy)
–
The
Latin Caudata and
Greek Urodela both mean "tailed" and have been used as a scientific name at the rank of order for the
salamanders (as opposed to the tail-less
frogs). Thus they are synonyms.
Synonym (taxonomy)
–
The common dandelion
Taraxacum officinale sensu lato is an extremely widespread group of
apomictic lineages, and some scientists apply the "biological species concept" to divide it into many distinct species; other scientists regard all the names for those independent species as synonyms.
11.
Flowering plant
–
The flowering plants, also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 416 families, approx. 13,164 known genera and a total of c.295,383 known species, etymologically, angiosperm means a plant that produces seeds within an enclosure, in other words, a fruiting plant. The term angiosperm comes from the Greek composite word meaning enclosed seeds, the ancestors of flowering plants diverged from gymnosperms in the Triassic Period, during the range 245 to 202 million years ago, and the first flowering plants are known from 160 mya. They diversified extensively during the Lower Cretaceous, became widespread by 120 mya, angiosperms differ from other seed plants in several ways, described in the table. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, the amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms. The vascular bundles of the stem are arranged such that the xylem and phloem form concentric rings, in the dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium, the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Among the monocotyledons, the bundles are more numerous in the stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases, the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species, the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf, occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. There are two kinds of cells produced by flowers. Microspores, which divide to become pollen grains, are the male cells and are borne in the stamens. The female cells called megaspores, which divide to become the egg cell, are contained in the ovule. The flower may consist only of parts, as in willow. Usually, other structures are present and serve to protect the sporophylls, the individual members of these surrounding structures are known as sepals and petals. The outer series is usually green and leaf-like, and functions to protect the rest of the flower, the inner series is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators, attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower
Flowering plant
Flowering plant
–
Bud of a pink
rose
Flowering plant
–
Flowers of
Malus sylvestris (crab apple)
Flowering plant
–
Flowers and leaves of
Oxalis pes-caprae (Bermuda buttercup)
12.
Eurasia
–
Eurasia /jʊˈreɪʒə/ is a combined continental landmass of Europe and Asia. The term is a portmanteau of its constituent continents, in geology, Eurasia is often considered as a single rigid megablock. However, the rigidity of Eurasia is debated based on the paleomagnet data, Eurasia covers around 55,000,000 square kilometres, or around 36. 2% of the Earths total land area. The landmass contains around 5.0 billion people, equating to approximately 70% of the human population, humans first settled in Eurasia between 60,000 and 125,000 years ago. Physiographically, Eurasia is a single continent, the concepts of Europe and Asia as distinct continents date back to antiquity and their borders are geologically arbitrary. Eurasia is connected to Africa at the Suez Canal, and Eurasia is sometimes combined with Africa as the largest contiguous landmass on Earth called Afro-Eurasia. Eurasia formed 375 to 325 million years ago with the merging of Siberia, Kazakhstania, and Baltica, chinese cratons collided with Siberias southern coast. Eurasia has been the host of ancient civilizations, including those based in Mesopotamia. In the Axial Age, a belt of civilizations stretched through the Eurasian subtropical zone from the Atlantic to the Pacific. This belt became the mainstream of world history for two millennia, originally, “Eurasia” is a geographical notion, in this sense, it is simply the biggest continent, the combined landmass of Europe and Asia. However, geopolitically, the word has different meanings, reflecting the specific geopolitical interests of each nation. “Eurasia” is one of the most important geopolitical concepts, as Zbigniew Brzezinski observed, how America manages Eurasia is critical. A power that dominates “Eurasia” would control two of the three most advanced and economically productive regions. About 75 per cent of the people live in “Eurasia”. “Eurasia” accounts for about three-fourths of the known energy resources. ”At the moment one of the most prominent projects of the European Union is the Russia - EU Four Common Spaces Initiative. A political and economic union of former Soviet states named the Eurasian Economic Union was established in 2015, the Russian concept of “Eurasia” corresponded initially more or less to the land area of Imperial Russia in 1914, including parts of Eastern Europe. One of Russias main geopolitical interests lies in ever closer integration with those countries that it considers part of “Eurasia. ”Every two years since 1996 a meeting of most Asian and European countries is organised as the Asia-Europe Meeting. In ancient times, the Greeks classified Europe and Asia as separate lands, where to draw the dividing line between the two regions is still a matter of discussion
Eurasia
–
Eurasia with surrounding areas of
Africa and
Australasia visible
Eurasia
–
Eurasia
Eurasia
–
Afro-Eurasian aspect of
Earth
13.
Annual plant
–
An annual plant is a plant that completes its life cycle, from germination to the production of seed, within one year, and then dies. Summer annuals germinate during spring or early summer and mature by autumn of the same year, winter annuals germinate during the autumn and mature during the spring or summer of the following calendar year. One seed-to-seed life cycle for an annual can occur in as little as a month in some species, oilseed rapa can go from seed-to-seed in about five weeks under a bank of fluorescent lamps. This style of growing is used in classrooms for education. Many desert annuals are therophytes, because their life cycle is only weeks. In cultivation, many plants are, or are grown as, annuals. Some perennials and biennials are grown in gardens as annuals for convenience, carrot, celery and parsley are true biennials that are usually grown as annual crops for their edible roots, petioles and leaves, respectively. Tomato, sweet potato and bell pepper are tender perennials usually grown as annuals, ornamental perennials commonly grown as annuals are impatiens, wax begonia, snapdragon, Pelargonium, coleus and petunia. Examples of true annuals include corn, wheat, rice, lettuce, peas, watermelon, beans, zinnia, summer annuals sprout, flower, produce seed, and die, during the warmer months of the year. The lawn weed crabgrass is a summer annual, winter annuals germinate in autumn or winter, live through the winter, then bloom in winter or spring. The plants grow and bloom during the season when most other plants are dormant or other annuals are in seed form waiting for warmer weather to germinate. Winter annuals die after flowering and setting seed, the seeds germinate in the autumn or winter when the soil temperature is cool. Winter annuals typically grow low to the ground, where they are sheltered from the coldest nights by snow cover. Some common winter annuals include henbit, deadnettle, chickweed, ironically, the property that they prevent the soil from drying out can also be problematic for commercial agriculture. In 2008, it was discovered that the inactivation of only two genes in one species of annual plant leads to the conversion into a perennial plant, researchers deactivated the SOC1 and FUL genes in Arabidopsis thaliana, which control flowering time. This switch established phenotypes common in plants, such as wood formation
Annual plant
–
Peas are an annual plant.
14.
Model organism
–
Model organisms are in vivo models and are widely used to research human disease when human experimentation would be unfeasible or unethical. This strategy is made possible by the descent of all living organisms. Studying model organisms can be informative, but care must be taken when extrapolating from one organism to another, in researching human disease, model organisms allow for better understanding the disease process without the added risk of harming an actual human. The species chosen will usually meet a determined taxonomic equivalency to humans, although biological activity in a model organism does not ensure an effect in humans, many drugs, treatments and cures for human diseases are developed in part with the guidance of animal models. There are three types of disease models, homologous, isomorphic and predictive. Homologous animals have the same causes, symptoms and treatment options as would humans who have the same disease, isomorphic animals share the same symptoms and treatments. Predictive models are similar to a human disease in only a couple of aspects. The use of animals in research dates back to ancient Greece, with Aristotle, research using animal models has been central to most of the achievements of modern medicine. It has contributed most of the knowledge in fields such as human physiology and biochemistry. For example, the results have included the near-eradication of polio and the development of organ transplantation, from 1910 to 1927, Thomas Hunt Morgans work with the fruit fly Drosophila melanogaster identified chromosomes as the vector of inheritance for genes. Drosophila became one of the first, and for some time the most widely used, model organisms, D. melanogaster remains one of the most widely used eukaryotic model organisms. The mouse has since been used extensively as an organism and is associated with many important biological discoveries of the 20th. In the late 19th century, Emil von Behring isolated the diphtheria toxin and he went on to develop an antitoxin against diphtheria in animals and then in humans, which resulted in the modern methods of immunization and largely ended diphtheria as a threatening disease. The diphtheria antitoxin is famously commemorated in the Iditarod race, which is modeled after the delivery of antitoxin in the 1925 serum run to Nome. The success of animal studies in producing the diphtheria antitoxin has also attributed as a cause for the decline of the early 20th-century opposition to animal research in the United States. This led to the 1922 discovery of insulin and its use in treating diabetes, modern general anaesthetics, such as halothane and related compounds, were also developed through studies on model organisms, and are necessary for modern, complex surgical operations. In the 1940s, Jonas Salk used rhesus monkey studies to isolate the most virulent forms of the polio virus, the vaccine, which was made publicly available in 1955, reduced the incidence of polio 15-fold in the United States over the following five years. It has been estimated that developing and producing the vaccines required the use of 100,000 rhesus monkeys, models are those organisms with a wealth of biological data that make them attractive to study as examples for other species and/or natural phenomena that are more difficult to study directly
Model organism
–
Escherichia coli is a
Gram-negative prokaryotic model organism
Model organism
–
Drosophila melanogaster, one of the most famous subjects for
genetics experiments
Model organism
–
Saccharomyces cerevisiae, one of the most intensively studied
eukaryotic model organisms in
molecular and
cell biology
Model organism
–
Electron microphotograph of
tobacco mosaic virus (TMV) particles
15.
Plant biology
–
Botany, also called plant science, plant biology or phytology, is the science of plant life and a branch of biology. A botanist or plant scientist is a scientist who specialises in this field, the term botany comes from the Ancient Greek word βοτάνη meaning pasture, grass, or fodder, βοτάνη is in turn derived from βόσκειν, to feed or to graze. Nowadays, botanists study approximately 410,000 species of plants of which some 391,000 species are vascular plants. Medieval physic gardens, often attached to monasteries, contained plants of medical importance and they were forerunners of the first botanical gardens attached to universities, founded from the 1540s onwards. One of the earliest was the Padua botanical garden and these gardens facilitated the academic study of plants. Efforts to catalogue and describe their collections were the beginnings of plant taxonomy, in the last two decades of the 20th century, botanists exploited the techniques of molecular genetic analysis, including genomics and proteomics and DNA sequences to classify plants more accurately. Modern botany is a broad, multidisciplinary subject with inputs from most other areas of science, dominant themes in 21st century plant science are molecular genetics and epigenetics, which are the mechanisms and control of gene expression during differentiation of plant cells and tissues. Botany originated as herbalism, the study and use of plants for their medicinal properties, many records of the Holocene period date early botanical knowledge as far back as 10,000 years ago. This early unrecorded knowledge of plants was discovered in ancient sites of human occupation within Tennessee, the early recorded history of botany includes many ancient writings and plant classifications. Examples of early works have been found in ancient texts from India dating back to before 1100 BC, in archaic Avestan writings. His major works, Enquiry into Plants and On the Causes of Plants, constitute the most important contributions to science until the Middle Ages. De Materia Medica was widely read for more than 1,500 years, important contributions from the medieval Muslim world include Ibn Wahshiyyas Nabatean Agriculture, Abū Ḥanīfa Dīnawarīs the Book of Plants, and Ibn Bassals The Classification of Soils. In the early 13th century, Abu al-Abbas al-Nabati, and Ibn al-Baitar wrote on botany in a systematic and scientific manner and these gardens continued the practical value of earlier physic gardens, often associated with monasteries, in which plants were cultivated for medical use. They supported the growth of botany as an academic subject, lectures were given about the plants grown in the gardens and their medical uses demonstrated. Botanical gardens came much later to northern Europe, the first in England was the University of Oxford Botanic Garden in 1621, throughout this period, botany remained firmly subordinate to medicine. German physician Leonhart Fuchs was one of the three German fathers of botany, along with theologian Otto Brunfels and physician Hieronymus Bock, Fuchs and Brunfels broke away from the tradition of copying earlier works to make original observations of their own. Bock created his own system of plant classification, physician Valerius Cordus authored a botanically and pharmacologically important herbal Historia Plantarum in 1544 and a pharmacopoeia of lasting importance, the Dispensatorium in 1546. Naturalist Conrad von Gesner and herbalist John Gerard published herbals covering the medicinal uses of plants, naturalist Ulisse Aldrovandi was considered the father of natural history, which included the study of plants
Plant biology
–
The fruit of
Myristica fragrans, a species native to
Indonesia, is the source of two valuable spices, the red aril (
mace) enclosing the dark brown
nutmeg.
Plant biology
–
The
Linnaean Garden of Linnaeus' residence in Uppsala, Sweden, was planted according to his Systema sexuale.
Plant biology
–
Micropropagation of transgenic plants
Plant biology
–
Biologist and statistician Ronald Fisher
16.
Eukaryote
–
A eukaryote is any organism whose cells contain a nucleus and other organelles enclosed within membranes. Eukaryotes belong to the taxon Eukarya or Eukaryota, the presence of a nucleus gives eukaryotes their name, which comes from the Greek εὖ and κάρυον. Eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the Golgi apparatus, in addition, plants and algae contain chloroplasts. Eukaryotic organisms may be unicellular or multicellular, only eukaryotes form multicellular organisms consisting of many kinds of tissue made up of different cell types. Eukaryotes can reproduce asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two identical cells. In meiosis, DNA replication is followed by two rounds of division to produce four daughter cells each with half the number of chromosomes as the original parent cell. These act as sex cells resulting from genetic recombination during meiosis, the domain Eukaryota appears to be monophyletic, and so makes up one of the three domains of life. The two other domains, Bacteria and Archaea, are prokaryotes and have none of the above features, eukaryotes represent a tiny minority of all living things. However, due to their larger size, eukaryotes collective worldwide biomass is estimated at about equal to that of prokaryotes. Eukaryotes first developed approximately 1. 6–2.1 billion years ago, in 1905 and 1910, the Russian biologist Konstantin Mereschkowsky argued three things about the origin of nucleated cells. Firstly, plastids were reduced cyanobacteria in a symbiosis with a non-photosynthetic host, secondly, the host had earlier in evolution formed by symbiosis between an amoeba-like host and a bacteria-like cell that formed the nucleus. Thirdly, plants inherited photosynthesis from cyanobacteria, the split between the prokaryotes and eukaryotes was introduced in the 1960s. The concept of the eukaryote has been attributed to the French biologist Edouard Chatton, the terms prokaryote and eukaryote were more definitively reintroduced by the Canadian microbiologist Roger Stanier and the Dutch-American microbiologist C. B. van Niel in 1962. In his 1938 work Titres et Travaux Scientifiques, Chatton had proposed the two terms, calling the bacteria prokaryotes and organisms with nuclei in their cells eukaryotes. However he mentioned this in one paragraph, and the idea was effectively ignored until Chattons statement was rediscovered by Stanier. In 1967, Lynn Margulis provided microbiological evidence for endosymbiosis as the origin of chloroplasts and mitochondria in cells in her paper. In the 1970s, Carl Woese explored microbial phylogenetics, studying variations in 16S ribosomal RNA and this helped to uncover the origin of the eukaryotes and the symbiogenesis of two important eukaryote organelles, mitochondria and chloroplasts
Eukaryote
–
Had'n
Eukaryote
–
Longitudinal section through the flagellum of
Chlamydomonas reinhardtii
17.
Genome
–
In modern molecular biology and genetics, a genome is the genetic material of an organism. The genome includes both the genes, the noncoding DNA and the material of the mitochondria and chloroplasts. The term genome was created in 1920 by Hans Winkler, professor of botany at the University of Hamburg, the Oxford Dictionary suggests the name is a blend of the words gene and chromosome. However, see omics for a thorough discussion. A few related -ome words already existed—such as biome, rhizome, Some organisms have multiple copies of chromosomes, diploid, triploid, tetraploid and so on. In classical genetics, in a sexually reproducing organism the gamete has half the number of chromosomes of the somatic cell, the halving of the genetic material in gametes is accomplished by the segregation of homologous chromosomes during meiosis. Additionally, the genome can comprise non-chromosomal genetic elements such as viruses, plasmids, even in species that exist in only one sex, what is described as a genome sequence may be a composite read from the chromosomes of various individuals. Colloquially, the genetic makeup is sometimes used to signify the genome of a particular individual or organism. Both the number of pairs and the number of genes vary widely from one species to another. The only exception in humans is found in red blood cells which become enucleated during development. In 1976, Walter Fiers at the University of Ghent was the first to establish the complete sequence of a viral RNA-genome. The next year Fred Sanger completed the first DNA-genome sequence, Phage Φ-X174, the first genome sequence for an archaeon, Methanococcus jannaschii, was completed in 1996, again by The Institute for Genomic Research. The development of new technologies has made it easier and cheaper to do sequencing. The US National Institutes of Health maintains one of several databases of genomic information. Among the thousands of completed genome sequencing projects include those for rice, a mouse, the plant Arabidopsis thaliana, the fish. In December 2013, scientists first sequenced the genome of a Neanderthal. The genome was extracted from the toe bone of a 130, new sequencing technologies, such as massive parallel sequencing have also opened up the prospect of personal genome sequencing as a diagnostic tool, as pioneered by Manteia Predictive Medicine. A major step toward that goal was the completion in 2007 of the genome of James D. Watson
Genome
–
An image of the 46 chromosomes making up the diploid genome of a human male. (The
mitochondrial chromosome is not shown.)
18.
Base pair
–
A base pair is a unit consisting of two nucleobases bound to each other by hydrogen bonds. They form the blocks of the DNA double helix. Dictated by specific hydrogen bonding patterns, Watson-Crick base pairs allow the DNA helix to maintain a regular helical structure that is dependent on its nucleotide sequence. The complementary nature of this structure provides a backup copy of all genetic information encoded within double-stranded DNA. Many DNA-binding proteins can recognize specific base pairing patterns that identify particular regulatory regions of genes, intramolecular base pairs can occur within single-stranded nucleic acids. The size of a gene or an organisms entire genome is often measured in base pairs because DNA is usually double-stranded. Hence, the number of base pairs is equal to the number of nucleotides in one of the strands. The haploid human genome is estimated to be about 3.2 billion bases long and to contain 20, a kilobase is a unit of measurement in molecular biology equal to 1000 base pairs of DNA or RNA. The total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037, in comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC. Hydrogen bonding is the interaction that underlies the base-pairing rules described above. Appropriate geometrical correspondence of hydrogen donors and acceptors allows only the right pairs to form stably. Purine-pyrimidine base pairing of AT or GC or UA results in proper duplex structure, the only other purine-pyrimidine pairings would be AC and GT and UG, these pairings are mismatches because the patterns of hydrogen donors and acceptors do not correspond. The GU pairing, with two bonds, does occur fairly often in RNA. Higher GC content results in higher melting temperatures, it is, therefore, on the converse, regions of a genome that need to separate frequently — for example, the promoter regions for often-transcribed genes — are comparatively GC-poor. GC content and melting temperature must also be taken into account when designing primers for PCR reactions, the following DNA sequences illustrate pair double-stranded patterns. By convention, the top strand is written from the 5 end to the 3 end, thus and this is due to their isosteric chemistry. One common mutagenic base analog is 5-bromouracil, which resembles thymine, most intercalators are large polyaromatic compounds and are known or suspected carcinogens. Examples include ethidium bromide and acridine, an unnatural base pair is a designed subunit of DNA which is created in a laboratory and does not occur in nature
Base pair
–
Depiction of the
adenine -
thymine Watson-Crick base pair.
19.
Molecular biology
–
Writing in Nature in 1961, William Astbury described molecular biology as. It is concerned particularly with the forms of biological molecules and is predominantly three-dimensional and structural—which does not mean, however and it must at the same time inquire into genesis and function. Researchers in molecular biology use specific techniques native to molecular biology but increasingly combine these techniques and ideas from genetics. There is not a line between these disciplines. Biochemists focus heavily on the role, function, and structure of biomolecules, the study of the chemistry behind biological processes and the synthesis of biologically active molecules are examples of biochemistry. Genetics is the study of the effect of differences on organisms. This can often be inferred by the absence of a normal component, the study of mutants – organisms which lack one or more functional components with respect to the so-called wild type or normal phenotype. Genetic interactions can often confound simple interpretations of such knockout studies, molecular biology is the study of molecular underpinnings of the processes of replication, transcription, translation, and cell function. This picture, however, is undergoing revision in light of emerging novel roles for RNA, much of molecular biology is quantitative, and recently much work has been done at its interface with computer science in bioinformatics and computational biology. In the early 2000s, the study of structure and function. There is also a tradition of studying biomolecules from the ground up in biophysics. One of the most basic techniques of molecular biology to study protein function is molecular cloning, in this technique, DNA coding for a protein of interest is cloned using PCR and/or restriction enzymes into a plasmid. A vector has 3 distinctive features, an origin of replication, a multiple cloning site, the origin of replication will have promoter regions upstream from the replication/transcription start site. This plasmid can be inserted into either bacterial or animal cells, introducing DNA into bacterial cells can be done by transformation via uptake of naked DNA, conjugation via cell-cell contact or by transduction via viral vector. Introducing DNA into eukaryotic cells, such as cells, by physical or chemical means is called transfection. Several different transfection techniques are available, such as calcium phosphate transfection, electroporation, microinjection, the plasmid may be integrated into the genome, resulting in a stable transfection, or may remain independent of the genome, called transient transfection. DNA coding for a protein of interest is now inside a cell, a variety of systems, such as inducible promoters and specific cell-signaling factors, are available to help express the protein of interest at high levels. Large quantities of a protein can then be extracted from the bacterial or eukaryotic cell, polymerase chain reaction is an extremely versatile technique for copying DNA
Molecular biology
–
Schematic relationship between
biochemistry,
genetics and molecular biology
20.
Flower
–
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in plants that are floral. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs, Flowers may facilitate outcrossing or allow selfing. Some flowers produce diaspores without fertilization, Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds, the essential parts of a flower can be considered in two parts, the vegetative part, consisting of petals and associated structures in the perianth, and the reproductive or sexual parts. A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk, each of these kinds of parts is arranged in a whorl on the receptacle. The four main whorls are as follows, Collectively the calyx, corolla, the next whorl toward the apex, composed of units called petals, which are typically thin, soft and colored to attract animals that help the process of pollination. Androecium, the whorl, consisting of units called stamens. Stamens consist of two parts, a called a filament, topped by an anther where pollen is produced by meiosis. Gynoecium, the innermost whorl of a flower, consisting of one or more units called carpels, the carpel or multiple fused carpels form a hollow structure called an ovary, which produces ovules internally. Ovules are megasporangia and they in turn produce megaspores by meiosis which develop into female gametophytes and these give rise to egg cells. The gynoecium of a flower is described using an alternative terminology wherein the structure one sees in the innermost whorl is called a pistil. A pistil may consist of a carpel or a number of carpels fused together. The sticky tip of the pistil, the stigma, is the receptor of pollen, the supportive stalk, the style, becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma. The relationship to the gynoecium on the receptacle is described as hypogynous, perigynous, although the arrangement described above is considered typical, plant species show a wide variation in floral structure. These modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species, the four main parts of a flower are generally defined by their positions on the receptacle and not by their function. Many flowers lack some parts or parts may be modified into other functions and/or look like what is typically another part, in some families, like Ranunculaceae, the petals are greatly reduced and in many species the sepals are colorful and petal-like. Other flowers have modified stamens that are petal-like, the flowers of Peonies and Roses are mostly petaloid stamens
Flower
–
A poster with flowers or clusters of flowers produced by twelve species of flowering plants from different families
Flower
–
Main parts of a mature flower (
Ranunculus glaberrimus)
Flower
–
Reproductive parts of Easter Lily (Lilium longiflorum). 1. Stigma, 2. Style, 3. Stamens, 4. Filament, 5. Petal
Flower
–
Left: A normal zygomorphic Streptocarpus flower. Right: An aberrant peloric Streptocarpus flower. Both of these flowers appeared on the Streptocarpus hybrid 'Anderson's Crows' Wings'.
21.
Phototropism
–
Phototropism is the growth of an organism which responds to a light stimulus. It is most often observed in plants, but can occur in other organisms such as fungi. The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs and this causes the plant to have elongated cells on the farthest 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. Most plant shoots exhibit positive phototropism, and rearrange their chloroplasts in the leaves to maximize photosynthetic energy, roots usually exhibit negative phototropism, although gravitropism may play a larger role in root behavior and growth. Some vine shoot tips exhibit negative phototropism, which allows them to grow dark, solid objects. The combination of phototropism and gravitropism allow plants to grow in the correct direction, the very tip of the plant known as the coleoptile is necessary in light sensing. The middle portion of the coleoptile is the area where the shoot curvature occurs, auxins activate proton pumps, decreasing the pH in the cells on the dark side of the plant. This acidification of the wall region activates enzymes known as expansins which break bonds in the cell wall structure. In addition, the environment causes disruption of hydrogen bonds in the cellulose that makes up the cell wall. The decrease in cell wall strength causes cells to swell, exerting the mechanical pressure that drives phototropic movement, a second group of genes, PIN genes, have been found to play a major role in phototropism. They are auxin transporters, so it is thought that they are responsible for the polarization of auxin, specifically PIN3 has been identified as the primary auxin carrier. It is possible that phototropins receive light and inhibit the activity of PINOID kinase and this activation of PIN3 leads to asymmetric distribution of auxin, which then leads to asymmetric elongation of cells in the stem. Pin3 mutants had shorter hypocotyls and roots than the wild-type, using anti-PIN3 immunogold labeling, movement of the PIN3 protein was observed. PIN3 is normally localized to the surface of hypocotyl and stem, but is also internalized in the presence of Brefeldin A and this mechanism allows PIN3 to be repositioned in response to an environmental stimulus. PIN3 and PIN7 proteins were thought to play a role in pulse-induced phototropism, the curvature responses in the pin3 mutant were reduced significantly, but only slightly reduced in pin7 mutants. There is some redundancy among PIN1, PIN3, and PIN7, there are phototropins that are highly expressed in the upper region of coleoptiles. The two main phototropins are phot1 and phot2, phot2 single mutants have phototropic responses like that of the wild-type, but phot1 phot2 double mutants do not show any phototropic responses
Phototropism
–
The Thale Cress (
Arabidopsis thaliana) is regulated by blue to UV light
Phototropism
–
The light from the lamp (1.) functions as a detectable change in the plant's environment. As a result, the plant exhibits a reaction of phototropism--directional growth (2.) toward the light stimulus
Phototropism
–
Phycomyces, a fungus, also exhibit phototropism
Phototropism
–
Example on a
Phalaenopsis
22.
Biennial plant
–
A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year, the plant grows leaves, stems, usually the stem remains very short and the leaves are low to the ground, forming a rosette. Many biennials require a treatment, or vernalization, before they will flower. During the next spring or summer, the stem of the biennial plant elongates greatly and this typically makes biennial vegetables such as spinach, fennel and lettuce unusable as food. The plant then flowers, producing fruits and seeds before it finally dies, there are far fewer biennials than either perennial plants or annual plants. Under extreme climatic conditions, a plant may complete its life cycle rapidly. This is quite common in vegetable or flower seedlings that were vernalized before they were planted in the ground and this behavior leads to many normally biennial plants being treated as annuals in some areas. From a gardeners perspective, a status as annual, biennial. Biennials grown for flowers, fruits, or seeds need to be grown for two years, biennials that are grown for edible leaves or roots are grown for just one year. Plant breeders have produced annual cultivars of several biennials that will flower the first year from seed, for example, foxglove and stock
Biennial plant
–
Parsley is a common example of a biennial plant.
Biennial plant
–
The Sweet William Dwarf plant is a biennial plant
23.
Leaf
–
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. Although leaves can be seen in different shapes, sizes and textures, typically a leaf is a thin, dorsiventrally flattened organ, borne above ground. Most leaves have distinctive upper surface and lower surface that differ in colour, hairiness, broad, flat leaves with complex venation are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants. In others, such as the clubmosses, with different evolutionary origins, some leaves, such as bulb scales are not above ground, and in many aquatic species the leaves are submerged in water. Succulent plants often have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls, furthermore, several kinds of leaf-like structures found in vascular plants are not totally homologous with them. Examples include flattened plant stems called phylloclades and cladodes, and flattened leaf stems called phyllodes which differ from both in their structure and origin. Many structures of plants, such as the phyllids of mosses and liverworts and even of some foliose lichens. Leaves are the most important organs of most vascular plants and these are then further processed by chemical synthesis into more complex organic molecules such as cellulose, the basic structural material in plant cell walls. The plant must therefore bring these three together in the leaf for photosynthesis to take place. Once sugar has been synthesized, it needs to be transported to areas of growth such as the plant shoots and roots. Vascular plants transport sucrose in a tissue called the phloem. The phloem and xylem are parallel to each other but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch to form veins which supply as much as the leaf as possible and 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, the flat, or laminar, shape also maximises thermal contact with the surrounding air, promoting cooling. Functionally, in addition to photosynthesis the leaf is the site of transpiration and guttation. Many gymnosperms have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and these are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. For xerophytes the major constraint is not light flux or intensity, 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
Leaf
–
The leaves of a
beech tree
Leaf
–
Near the ground these
Eucalyptus saplings have juvenile dorsiventral foliage from the previous year, but this season their newly sprouting foliage is isobilateral, like the mature foliage on the adult trees above
Leaf
–
A leaf shed in
autumn.
Leaf
–
Cross-section of a leaf
24.
Trichome
–
Trichomes, from the Greek τρίχωμα meaning hair, are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function, examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant is an indumentum, certain, usually filamentous, algae have the terminal cell produced into an elongate hair-like structure called a trichome. The same term is applied to structures in some cyanobacteria, such as Spirulina. Cyanobacteria trichomes may be unsheathed, as in Oscillatoria, or sheathed and these structures play an important role in preventing soil erosion, particularly in cold desert climates. The filamentous sheaths form a persistent sticky network that helps maintain soil structure, trichomes on plants are epidermal outgrowths of various kinds. The terms emergences or prickles refer to outgrowths that involve more than the epidermis and this distinction is not always easily applied. Also, there are nontrichomatous epidermal cells that protrude from the surface, a common type of trichome is a hair. Plant hairs may be unicellular or multicellular, branched or unbranched, multicellular hairs may have one or several layers of cells. Branched hairs can be dendritic as in kangaroo paw, tufted, or stellate, another common type of trichome is the scale or peltate hair, that has a plate or shield-shaped cluster of cells attached directly to the surface or borne on a stalk of some kind. Common examples are the scales of bromeliads such as the pineapple, Rhododendron. Any of the types of hairs may be glandular, producing some kind of secretion, such as the essential oils produced by mints. In describing the appearance of plant organs, such as stems and leaves, many terms are used in reference to the presence, form. The most basic terms used are glabrous—lacking hairs— and pubescent—having hairs, however, several basic functions or advantages of having surface hairs can be listed. It is likely that in cases, hairs interfere with the feeding of at least some small herbivores. Hairs on plants growing in areas subject to frost keep the frost away from the surface cells. In windy locations, hairs break up the flow of air across the plant surface, dense coatings of hairs reflect sunlight, protecting the more delicate tissues underneath in hot, dry, open habitats. In addition, in locations where much of the moisture comes from fog drip
Trichome
–
Flower bud of a
Capsicum pubescens plant, with many trichomes
Trichome
–
Sticky trichomes of a
carnivorous plant,
Drosera capensis with a trapped insect
Trichome
–
Trichomes on
Cannabis, rich in
cannabinoids.
Trichome
–
Trichomes on the surface of a
Solanum scabrum leaf
25.
Inflorescence
–
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the part of the shoot of seed plants where flowers are formed. Inflorescence can also be defined as the portion of a plant that bears a cluster of flowers in a specific pattern. The stem holding the whole inflorescence is called a peduncle and the major axis holding the flowers or more branches within the inflorescence is called the rachis, the stalk of each single flower is called a pedicel. A flower that is not part of an inflorescence is called a solitary flower, any flower in an inflorescence may be referred to as a floret, especially when the individual flowers are particularly small and borne in a tight cluster, such as in a pseudanthium. The fruiting stage of an inflorescence is known as an infructescence, inflorescences may be simple or complex. The rachis may be one of several types, including Single, Composite, Umbel and these terms are general representations as plants in nature can have a combination of types. Inflorescences usually have modified shoots foliage different from the part of the plant. Considering the broadest meaning of the term, any leaf associated with an inflorescence is called a bract. A bract is usually located at the node where the stem of the inflorescence forms, joined to the main stem of the plant. They serve a variety of functions which include attracting pollinators and protecting young flowers, according to the presence or absence of bracts and their characteristics we can distinguish, Ebracteate inflorescences, No bracts in the inflorescence. Bracteate inflorescences, The bracts in the inflorescence are very specialised, sometimes reduced to small scales and this use is not technically correct, as, despite their normal appearance, these leaves are considered, in fact, bracts, so that leafy inflorescence is preferable. Leafy-bracted inflorescences, Intermediate between bracteate and leafy inflorescence, if many bracts are present and they are strictly connected to the stem, like in the family Asteraceae, the bracts might collectively be called an involucre. If the inflorescence has a unit of bracts further up the stem. Plant organs can grow according to two different schemes, namely monopodial or racemose and sympodial or cymose, the terminal bud keeps growing and forming lateral flowers. A terminal flower is never formed, the terminal bud forms a terminal flower and then dies out. Other flowers then grow from lateral buds, indeterminate and determinate inflorescences are sometimes referred to as open and closed inflorescences respectively. In an indeterminate inflorescence there is no true terminal flower and the stem usually has a rudimentary end, in many cases the last true flower formed by the terminal bud straightens up, appearing to be a terminal flower
Inflorescence
–
Aloe hereroensis, showing inflorescence with branched
peduncle
Inflorescence
–
Ebracteate of
Wisteria sinensis
Inflorescence
–
Bracteate inflorescence of
Pedicularis verticillata.
Inflorescence
–
Leafy-bracted inflorescence of
Rhinanthus angustifolius.
26.
Fruit
–
In botany, a fruit is the seed-bearing structure in flowering plants formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds, accordingly, fruits account for a substantial fraction of the worlds agricultural output, and some have acquired extensive cultural and symbolic meanings. On the other hand, in usage, fruit includes many structures that are not commonly called fruits, such as bean pods, corn kernels, tomatoes. The section of a fungus that produces spores is called a fruiting body. Many common terms for seeds and fruit do not correspond to the botanical classifications, however, in botany, a fruit is the ripened ovary or carpel that contains seeds, a nut is a type of fruit and not a seed, and a seed is a ripened ovule. Examples of culinary vegetables and nuts that are botanically fruit include corn, cucurbits, eggplant, legumes, sweet pepper, in addition, some spices, such as allspice and chili pepper, are fruits, botanically speaking. g. Botanically, a grain, such as corn, rice, or wheat, is also a kind of fruit. However, the wall is very thin and is fused to the seed coat. The outer, often edible layer, is the pericarp, formed from the ovary and surrounding the seeds, the pericarp may be described in three layers from outer to inner, the epicarp, mesocarp and endocarp. Fruit that bears a prominent pointed terminal projection is said to be beaked, a fruit results from maturation of one or more flowers, and the gynoecium of the flower forms all or part of the fruit. Inside the ovary/ovaries are one or more ovules where the megagametophyte contains the egg cell, after double fertilization, these ovules will become seeds. The ovules are fertilized in a process starts with pollination. After pollination, a tube grows from the pollen through the stigma into the ovary to the ovule, later the zygote will give rise to the embryo of the seed, and the endosperm mother cell will give rise to endosperm, a nutritive tissue used by the embryo. As the ovules develop into seeds, the ovary begins to ripen and the ovary wall, in some multiseeded fruits, the extent to which the flesh develops is proportional to the number of fertilized ovules. The pericarp is often differentiated into two or three distinct layers called the exocarp, mesocarp, and endocarp, in some fruits, especially simple fruits derived from an inferior ovary, other parts of the flower, fuse with the ovary and ripen with it. In other cases, the sepals, petals and/or stamens and style of the fall off. When such other floral parts are a significant part of the fruit, it is called an accessory fruit, since other parts of the flower may contribute to the structure of the fruit, it is important to study flower structure to understand how a particular fruit forms. There are three modes of fruit development, Apocarpous fruits develop from a single flower having one or more separate carpels
Fruit
–
Culinary fruits
Fruit
–
Several
culinary fruits
Fruit
–
Mixed fruit
Fruit
–
Fruit shop in
Naggar,
Himachal Pradesh,
India
27.
Seed
–
A seed is an embryonic plant enclosed in a protective outer covering. The formation of the seed is part of the process of reproduction in seed plants, Seeds are the product of the ripened ovule, after fertilization by pollen and some growth within the mother plant. The embryo is developed from the zygote and the coat from the integuments of the ovule. Seed plants now dominate biological niches on land, from forests to both in hot and cold climates. The term seed also has a meaning that antedates the above—anything that can be sown, e. g. seed potatoes. In the case of sunflower and corn seeds, what is sown is the seed enclosed in a shell or husk, many structures commonly referred to as seeds are actually dry fruits. Plants producing berries are called baccate, sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Different groups of plants have other modifications, the stone fruits have a hardened fruit layer fused to. Nuts are the one-seeded, hard-shelled fruit of plants with an indehiscent seed. Seeds are produced in several related groups of plants, and their manner of production distinguishes the angiosperms from the gymnosperms, angiosperm seeds are produced in a hard or fleshy structure called a fruit that encloses the seeds, hence the name. Some fruits have layers of hard and fleshy material. In gymnosperms, no special structure develops to enclose the seeds, however, the seeds do become covered by the cone scales as they develop in some species of conifer. Seed production in natural plant populations varies widely from year-to-year in response to weather variables, insects and diseases, over a 20-year period, for example, forests composed of loblolly pine and shortleaf pine produced from 0 to nearly 5 million sound pine seeds per hectare. Over this period, there were six bumper, five poor, and nine good seed crops, right after fertilization, the zygote is mostly inactive, but the primary endosperm divides rapidly to form the endosperm tissue. This tissue becomes the food the young plant will consume until the roots have developed after germination, after fertilization the ovules develop into the seeds. The ovule consists of a number of components, The funicle or seed stalk which attaches the ovule to the placenta and hence ovary or fruit wall, the nucellus, the remnant of the megasporangium and main region of the ovule where the megagametophyte develops. The micropyle, a pore or opening in the apex of the integument of the ovule where the pollen tube usually enters during the process of fertilization. The chalaza, the base of the ovule opposite the micropyle, the shape of the ovules as they develop often affects the final shape of the seeds
Seed
–
Brown
flax seeds
Seed
–
The inside of a
Ginkgo seed, showing a well-developed embryo, nutritive tissue (
megagametophyte), and a bit of the surrounding seed coat
Seed
–
Layers within an endospermic maize seed
Seed
–
A collection of various vegetable and herb seeds
28.
Rhizosphere (ecology)
–
The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. Soil which is not part of the rhizosphere is known as bulk soil, the rhizosphere contains many bacteria that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots. Protozoa and nematodes that graze on bacteria are more abundant in the rhizosphere. Thus, much of the nutrient cycling and disease suppression needed by plants occurs immediately adjacent to roots, plants secrete many compounds through their roots to serve symbiotic functions in the rhizosphere. Strigolactones, secreted and detected by mycorrhizal fungi, stimulate the germination of spores, the parasitic plant, Striga also detects the presence of strigolactones and will germinate when it detects them, they will then move into the root, feeding off the nutrients present. In these nodules bacteria, sustained by nutrients from the plant, non-symbiotic nitrogen-fixing bacteria may reside in the rhizosphere just outside the roots of certain plants, and similarly fix nitrogen gas in the nutrient-rich plant rhizosphere. Even though these organisms are thought to be loosely associated with plants they inhabit. Although it goes beyond the area, it is to note that some plants secrete allelochemicals from their roots which inhibit the growth of other organisms. Trichoderma Root microbiome Soil respiration Allelopathy Bulk soil Root mucilage The Soil Habitat, digging in the Dirt, Is the Study of the Rhizosphere Ripe for a Systems Biology Approach. - A review from the Science Creative Quarterly The Rhizosphere - Roots, Soil and Everything In Between - Nature Education
Rhizosphere (ecology)
–
An illustration of the rhizosphere. A=
Amoeba consuming bacteria; BL=Energy limited
bacteria; BU=Non-energy limited bacteria; RC=Root derived carbon; SR=Sloughed root hair cells; F=Fungal
hyphae; N=
Nematode worm
29.
Bacillus megaterium
–
Bacillus megaterium is a rod-like, Gram-positive, mainly aerobic spore forming bacterium found in widely diverse habitats. With a cell length of up to 4 µm and a diameter of 1.5 µm, the cells often occur in pairs and chains, where the cells are joined together by polysaccharides on the cell walls. Recently, its popularity has started increasing in the field of biotechnology for its recombinant protein production capacity, B. megaterium grows at temperatures from 3 °C to 45 °C, with the optimum around 30 °C. Nitrogen fixation has been demonstrated in some strains of B. megaterium, B. megaterium has been an important industrial organism for decades. It produces penicillin amidase used to make synthetic penicillin, various amylases used in the baking industry, further, it is used for the production of pyruvate, vitamin B12, drugs with fungicidal and antiviral properties, etc. It produces enzymes for modifying corticosteroids, as well as amino acid dehydrogenases. B. megaterium is known to produce poly-γ-glutamic acid, the accumulation of the polymer is greatly increased in a saline environment, in which the polymer comprises largely of L-glutamate. At least one strain of B. megaterium can be considered a halophile, phylogenetically, based on 16S rRNA, B. megaterium is strongly linked with B. flexus, the latter distinguished from B. megaterium a century ago, but only recently confirmed as a different species. B. megaterium has some phenotypic and phylogenetic similarities with pathogens B. anthracis and B. cereus, B. megaterium is ubiquitous in the environment around us. In addition to being a common soil bacterium and an endophyte, it can be found in foods and on a variety of surfaces, including clinical specimens, leather, paper. It has also been isolated from cow feces, Emperor Moth caterpillars, the method of described in can be used to isolate strains of B. megaterium from the soil. Plates are incubated at 30 °C, white, round, smooth and shiny colonies 1–3 mm in diameter may develop on the nitrate medium in 36–48 hours. However, not all strains can use nitrate, therefore the recommendation to use the medium in parallel. Colonies are detected by their appearance and suspects should be observed microscopically for the large cells of this species. The species was described by de Bary in 1884, who called it Bacillus megaterium, however, some subsequent authors called it B. megatherium assuming the name was incorrectly spelled. This trend continues as many still use the name B. megatherium. The name B. megaterium is a noun in apposition and is formed from the Greek adjective mega, meaning great. Three hypotheses of the epithet megaterium are possible, unintentional orthographic error, whereas it should have been megatherium, from therion, consequently, it was decided in the first jouridical opinion of the Bacteriological code that the name should remain megaterium given the unclear meaning
Bacillus megaterium
–
Bacillus megaterium
30.
Scanning electron microscope
–
A scanning electron microscope is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography. The electron beam is scanned in a raster scan pattern. SEM can achieve better than 1 nanometer. Specimens can be observed in vacuum, in low vacuum, in wet conditions. The most common SEM mode is detection of electrons emitted by atoms excited by the electron beam. The number of electrons that can be detected depends, among other things. By scanning the sample and collecting the electrons that are emitted using a special detector. An account of the history of SEM has been presented by McMullan. Ardenne applied the principle not only to achieve magnification but also to purposefully eliminate the chromatic aberration otherwise inherent in the electron microscope. He further discussed the various modes, possibilities and theory of SEM. The types of produced by an SEM include secondary electrons, reflected or back-scattered electrons, photons of characteristic X-rays and light, absorbed current. Secondary electron detectors are standard equipment in all SEMs, but it is rare that a machine would have detectors for all other possible signals. The signals result from interactions of the beam with atoms at various depths within the sample. In the most common or standard detection mode, ie secondary electron imaging or SEI, consequently, SEM can produce very high-resolution images of a sample surface, revealing details less than 1 nm in size. Back-scattered electrons are beam electrons that are reflected from the sample by elastic scattering and they emerge from deeper locations within the specimen and consequently the resolution of BSE images is generally poorer than SE images. BSE images can provide information about the distribution of different elements in the sample, characteristic X-rays are emitted when the electron beam removes an inner shell electron from the sample, causing a higher-energy electron to fill the shell and release energy. These characteristic X-rays are used to identify the composition and measure the abundance of elements in the sample, due to the very narrow electron beam, SEM micrographs have a large depth of field yielding a characteristic three-dimensional appearance useful for understanding the surface structure of a sample
Scanning electron microscope
–
These
pollen grains taken on an SEM show the characteristic
depth of field of SEM
micrographs.
Scanning electron microscope
–
M. von Ardenne's first SEM
Scanning electron microscope
–
SEM opened sample chamber
Scanning electron microscope
–
Analog type SEM
31.
Harz Mountains
–
The Harz is a Mittelgebirge that has the highest elevations in Northern Germany and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The name Harz derives from the Middle High German word Hardt or Hart, the Brocken is the highest summit in the Harz with an elevation of 1,141.1 metres above sea level. The Wurmberg is the highest peak located entirely within the state of Lower Saxony, the Harz has a length of 110 kilometres, stretching from the town of Seesen in the northwest to Eisleben in the east, and a width of 35 kilometres. The following districts fall wholly or partly within the Harz, Goslar and Osterode am Harz in the west, Harz and Mansfeld-Südharz in the north and east, and Nordhausen in the south. The districts of the Upper Harz are Goslar and Osterode, whilst the Lower Harz is on the territory of Harz and Mansfeld-Südharz districts. The Upper Harz is generally higher and features fir forests, whilst the Lower Harz gradually descends into the area and has deciduous forests interspersed with meadows. The dividing line between Upper and Lower Harz follows approximately a line from Ilsenburg to Bad Lauterberg, which separates the catchment areas for the Weser. Only on the perimeter of the Upper Harz, which is also called the High Harz. Its highest peak is the Brocken, its peaks are the Heinrichshöhe to the southeast. Other prominent hills in the Harz are the Acker-Bruchberg ridge, the Achtermannshöhe, in the far east, the mountains merge into the East Harz foothills, which are dominated by the Selke Valley. Part of the south Harz lies in the Thuringian district of Nordhausen, the Harz National Park is located in the Harz, the protected area covers the Brocken and surrounding wilderness area. Approximately 600,000 people live in towns and villages of the Harz Mountains, because of the heavy rainfall in the region the rivers of the Harz Mountains were dammed from an early date. Examples of such dams are the two largest, the Oker Dam and the Rappbode Dam. The clear, cool water of the streams was also dammed by early mountain folk to form the various mountain ponds of the Upper Harz waterways. The 17 dams in the Harz block a total of twelve rivers, because the Harz is one of the regions of Germany that experiences the most rainfall, its water power was used from early times. Today the dams are used to generate electricity, to provide drinking water, to prevent flooding. Modern dam-building began in the Harz with the construction of the Söse Valley Dam, the dams of the Upper Harz lakes are some of the oldest dams in Germany that are still in operation. → See List of dams in the Harz The largest rivers in the Harz are the Innerste, the Oker and the Bode in the north, the Wipper in the east, the Innerste merges into the Leine and its tributaries are the Nette and the Grane
Harz Mountains
–
Panorama in the Harz Mountains. From left to right: the peaks of the Rehberg, the Achtermannshöhe, the Brocken and the Wurmberg.
Harz Mountains
Harz Mountains
–
Sender Brocken at the summit in winter
Harz Mountains
–
Reservoir behind the
Wendefurth Dam
32.
Nordhausen
–
Nordhausen is a city in Thuringia, Germany. It is the capital of the Nordhausen district and the centre of northern Thuringia. Nordhausen is located approximately 60 km N of Erfurt,80 km W of Halle,85 km S of Braunschweig and 60 km E of Göttingen. Nordhausen was first mentioned in records in the year 927 and became one of the most important cities in central Germany during the later Middle Ages. The city is situated at Zorge river, a tributary of the Helme within the region of Goldene Aue at the southern edge of the Harz mountains. In the early 13th century, it became an imperial city, so that it was an independent. Due to its trade, Nordhausen was prosperous and influential. It was the third-largest city in Thuringia after Erfurt, todays capital, and Mühlhausen, Nordhausen was once known for its tobacco industry and is still known for its distilled spirit, Nordhäuser Doppelkorn. Industrialization accompanied railway construction that linked the cities to major markets in the mid-19th century, in the late 19th century, narrow-gauge railways were constructed in this region through the Harz mountains. In December 1898 the Nordhausen-Wernigerode Railway Company or NWE added a line, the Harz Narrow Gauge Railways are maintained today by local authorities and frequented primarily by tourists. In the early 20th century, this became a center of the engineering, during World War II, the Nazi German government established and operated the nearby KZ Mittelbau-Dora concentration camp, where 60,000 forced labourers had to work in the arms industry. They were prisoners of war and persons from occupied territories, some 20,000 persons died because of the bad conditions. In April 1945, most of the city was destroyed by Royal Air Force bombings, most of the historic buildings of the city were destroyed, it suffered the most damage during the war of any city in Thuringia. A week later the United States troops occupied the city, followed later by the Soviet Red Army. The city was within the Soviet zone of occupation, and later the territory was known as East Germany, hundreds of German scientists and their families from Nordhausen were among thousands deported to the Soviet Union after the war to work on advanced rocket and other arms engineering projects. Nordhausen is the birthplace of the famous mathematician Oswald Teichmüller, known for his work on the Teichmüller spaces – which were named after him. It is the site of the Nordhausen University of Applied Sciences, the Franks colonized the area around Nordhausen about 800, many place names here have a Frankish origin, discernible by the suffix -hausen. Nordhausen itself is first mentioned in a 13 May 927 document of King Henry the Fowler and he built a castle here, which is traceable between 910 and 1277 and became a centre of the empire during the 10th century
Nordhausen
–
View of Nordhausen (city centre)
Nordhausen
–
Nordhausen in the 17th century
Nordhausen
–
Underground factory of KZ Mittelbau-Dora
Nordhausen
–
The destroyed Boelcke Kaserne and hundreds of killed interned forced labourers after the bombings in 1945
33.
Gustav Heynhold
–
Gustav Heynhold was a German botanist who worked at the botanic gardens of Dresden and Frankfurt. In 1828 he was in Trieste where he carried out mapping and published Uebersicht der Vegetation in den Umgebungen Triests and his best-known work was the Nomenclator Botanicus Hortensis, an index of the botanical names of garden plants. It is not certain whether he had a degree or title. In 1846 the Botanischen Centralblatt für Deutschland listed him as a scholar in Dresden. In total he was responsible for naming some 426 plant species, in 1841, he renamed Arabis thaliana as Arabidopsis thaliana Heynh. Das natürliche Pflanzensystem, ein Versuch, die gegenseitigen Verwandtschaften der Pflanzen aufzufinden, mit Berücksichtigung der arzneilichen und überhaupt anwendbaren Gewächse, nebst einer historischen Einleitung, Publisher, Dresden, Leipzig, in der Arnoldischen Buchhandlung,1840. Nomenclator Botanicus Hortensis in 2 parts Flora von Sachsen. wildwachsenden und allgemein angebauten Pflanzen Dresden, Verlag, regensburg,1829 - Uebersicht der Vegetation in den Umgebungen Triests, von Hrn. 1823 Works by or about Gustav Heynhold at Internet Archive Gustav Heynhold on ipni. org
Gustav Heynhold
–
Arabidopsis thaliana
34.
Greek (language)
–
Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
Greek (language)
–
Idealized portrayal of
Homer
Greek (language)
–
regions where Greek is the official language
Greek (language)
–
Greek language road sign, A27 Motorway, Greece
35.
Arabis
–
Arabis /ˈɛərəbᵻs/, or rockcress, is a genus of flowering plants, within the family Brassicaceae, subfamily Brassicoideae. The species are herbaceous, annual or perennial plants, growing to 10–80 cm tall, usually hairy, with simple entire to lobed leaves 1–6 cm long. The fruit is a long, slender capsule containing 10-20 or more seeds and these two groups are not each others closest relatives, so have been split into two separate genera. Most of the Old World members remain in the genus Arabis, whereas most of the New World members have moved into the genus Boechera. Selected species Arabis aculeolata Arabis alpina Arabis armena Arabis blepharophylla Arabis caucasica Willd, many others are regarded as weeds
Arabis
–
Arabis
Arabis
–
Arabis procurrens flowers
Arabis
–
Arabis blepharophylla
Arabis
–
Siliques of Arabis turrita
36.
Europe
–
Europe is a continent that comprises the westernmost part of Eurasia. Europe is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, yet the non-oceanic borders of Europe—a concept dating back to classical antiquity—are arbitrary. Europe covers about 10,180,000 square kilometres, or 2% of the Earths surface, politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a population of about 740 million as of 2015. Further from the sea, seasonal differences are more noticeable than close to the coast, Europe, in particular ancient Greece, was the birthplace of Western civilization. The fall of the Western Roman Empire, during the period, marked the end of ancient history. Renaissance humanism, exploration, art, and science led to the modern era, from the Age of Discovery onwards, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at times the Americas, most of Africa, Oceania. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to economic, cultural, and social change in Western Europe. During the Cold War, Europe was divided along the Iron Curtain between NATO in the west and the Warsaw Pact in the east, until the revolutions of 1989 and fall of the Berlin Wall. In 1955, the Council of Europe was formed following a speech by Sir Winston Churchill and it includes all states except for Belarus, Kazakhstan and Vatican City. Further European integration by some states led to the formation of the European Union, the EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The European Anthem is Ode to Joy and states celebrate peace, in classical Greek mythology, Europa is the name of either a Phoenician princess or of a queen of Crete. The name contains the elements εὐρύς, wide, broad and ὤψ eye, broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. For the second part also the divine attributes of grey-eyed Athena or ox-eyed Hera. The same naming motive according to cartographic convention appears in Greek Ανατολή, Martin Litchfield West stated that phonologically, the match between Europas name and any form of the Semitic word is very poor. Next to these there is also a Proto-Indo-European root *h1regʷos, meaning darkness. Most major world languages use words derived from Eurṓpē or Europa to refer to the continent, in some Turkic languages the originally Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa
Europe
–
Reconstruction of
Herodotus ' world map
Europe
Europe
–
A medieval
T and O map from 1472 showing the three continents as domains of the sons of
Noah — Asia to Sem (
Shem), Europe to Iafeth (
Japheth), and Africa to Cham (
Ham)
Europe
–
Early modern depiction of
Europa regina ('Queen Europe') and the mythical
Europa of the 8th century BC.
37.
Asia
–
Asia covers an area of 44,579,000 square kilometres, about 30% of Earths total land area and 8. 7% of the Earths total surface area. The continent, which has long been home to the majority of the population, was the site of many of the first civilizations. Asia is notable for not only its large size and population. In general terms, Asia is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean, the western boundary with Europe is a historical and cultural construct, as there is no clear physical and geographical separation between them. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of the Caucasus Mountains, China and India alternated in being the largest economies in the world from 1 to 1800 A. D. The accidental discovery of America by Columbus in search for India demonstrates this deep fascination, the Silk Road became the main East-West trading route in the Asian hitherland while the Straits of Malacca stood as a major sea route. Asia has exhibited economic dynamism as well as robust population growth during the 20th century, given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may actually have more to do with human geography than physical geography. Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties, the boundary between Asia and Africa is the Red Sea, the Gulf of Suez, and the Suez Canal. This makes Egypt a transcontinental country, with the Sinai peninsula in Asia, the border between Asia and Europe was historically defined by European academics. In Sweden, five years after Peters death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia, the Russians were enthusiastic about the concept, which allowed them to keep their European identity in geography. Tatishchev announced that he had proposed the idea to von Strahlenberg, the latter had suggested the Emba River as the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century, the border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects. The border between the Black Sea and the Caspian is usually placed along the crest of the Caucasus Mountains, the border between Asia and the loosely defined region of Oceania is usually placed somewhere in the Malay Archipelago. The terms Southeast Asia and Oceania, devised in the 19th century, have had several different geographic meanings since their inception. The chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the possessions of the various empires there. Lewis and Wigen assert, The narrowing of Southeast Asia to its present boundaries was thus a gradual process, Asia is larger and more culturally diverse than Europe. It does not exactly correspond to the borders of its various types of constituents. From the time of Herodotus a minority of geographers have rejected the three-continent system on the grounds there is no or is no substantial physical separation between them
Asia
–
Two-point equidistant projection of Asia and surrounding landmasses.
Asia
–
Asia
Asia
–
The racial diversity of Asia's peoples,
Nordisk familjebok (1904)
Asia
–
Ptolemy's Asia
38.
Humans
–
Modern humans are the only extant members of Hominina tribe, a branch of the tribe Hominini belonging to the family of great apes. Several of these hominins used fire, occupied much of Eurasia and they began to exhibit evidence of behavioral modernity around 50,000 years ago. In several waves of migration, anatomically modern humans ventured out of Africa, the spread of humans and their large and increasing population has had a profound impact on large areas of the environment and millions of native species worldwide. Humans are uniquely adept at utilizing systems of communication for self-expression and the exchange of ideas. Humans create complex structures composed of many cooperating and competing groups, from families. Social interactions between humans have established a wide variety of values, social norms, and rituals. These human societies subsequently expanded in size, establishing various forms of government, religion, today the global human population is estimated by the United Nations to be near 7.5 billion. In common usage, the word generally refers to the only extant species of the genus Homo—anatomically and behaviorally modern Homo sapiens. In scientific terms, the meanings of hominid and hominin have changed during the recent decades with advances in the discovery, there is also a distinction between anatomically modern humans and Archaic Homo sapiens, the earliest fossil members of the species. The English adjective human is a Middle English loanword from Old French humain, ultimately from Latin hūmānus, the words use as a noun dates to the 16th century. The native English term man can refer to the species generally, the species binomial Homo sapiens was coined by Carl Linnaeus in his 18th century work Systema Naturae. The generic name Homo is a learned 18th century derivation from Latin homō man, the species-name sapiens means wise or sapient. Note that the Latin word homo refers to humans of either gender, the genus Homo evolved and diverged from other hominins in Africa, after the human clade split from the chimpanzee lineage of the hominids branch of the primates. The closest living relatives of humans are chimpanzees and gorillas, with the sequencing of both the human and chimpanzee genome, current estimates of similarity between human and chimpanzee DNA sequences range between 95% and 99%. The gibbons and orangutans were the first groups to split from the leading to the humans. The splitting date between human and chimpanzee lineages is placed around 4–8 million years ago during the late Miocene epoch, during this split, chromosome 2 was formed from two other chromosomes, leaving humans with only 23 pairs of chromosomes, compared to 24 for the other apes. There is little evidence for the divergence of the gorilla, chimpanzee. Each of these species has been argued to be an ancestor of later hominins
Humans
Humans
–
Reconstruction of
Homo habilis, the earliest known species of the genus Homo and the first human ancestor to use stone tools
Humans
–
World map of early human migrations according to
mitochondrial population genetics (numbers are
millennia before present, the North Pole is at the center).
Humans
–
The rise of
agriculture, and
domestication of animals, led to stable
human settlements.
39.
Alexander Braun
–
Alexander Carl Heinrich Braun was a German botanist from Regensburg, Bavaria. His research centered on the morphology of plants and he studied botany in Heidelberg, Paris and Munich. In 1833 he began teaching botany at the Polytechnic School of Karlsruhe, afterwards he was a professor of botany in Freiburg, Giessen and at the University of Berlin, where he remained until 1877. While in Berlin, he was director of the botanical garden. In 1852, he was elected a member of the Royal Swedish Academy of Sciences. Braun is largely known for his research involving plant morphology and he was a proponent of vitalism, a popular 19th century speculative theory that claimed that a regulative force existed within living matter in order to maintain functionality. Despite these beliefs, Braun made important contributions in the field of cell theory, from his 1830s analysis of the arrangement of scales on a pine cone he was a pioneer of phyllotaxis. In 1877 Wilhelm Philippe Schimper and Philipp Bruch named the plant genus Braunia in his honor, also, a decorative plant known as Brauns holly fern commemorates his name. 1831, Untersuchung über die Ordnung der Schuppen an den Tannenzapfen,1842, Nachträgliche Mitteilungen über die Gattungen Marsilia und Pilularia. 1850, Betrachtungen über die Erscheinung der Verjüngung in der Natur,1852, Über die Richtungsverhältnisse der Saftströme in den Zellen der Characeen. 1853, Das Individuum der Pflanze in seinem Verhältnis zur Spezies etc,1854, Über den schiefen Verlauf der Holzfaser und die dadurch bedingte Drehung der Stämme 1854, Über einige neue und weniger bekannte Krankheiten der Pflanzen, welche durch Pilze erzeugt werden. 1854, Das Individuum der Species in seinem Verhältnis zur Pflanze,1855, Algarum unicellularium genera nova et minus cognita. 1856, Über Chytridium, eine Gattung einzelliger Schmarotzergewächse auf Algen und Infusorien,1857, Über Parthenogenesis bei Pflanzen 1860, Über Polyembryonie und Keimung von Caelebogyne. 1861, Index seminum Horti Botanici Berolinensis, Appendix Plantarum Novrum et minus cognitarum quea in Horto region botanico Berolinensi coluntur,1862, Über die Bedeutung der Morphologie. 1865, Beitrag zur Kenntnis der Gattung Selaginella,1870, Neuere Untersuchungen über die Gattungen Marsilia und Pilularia. 1872, Über die Bedeutung der Entwicklung in der Naturgeschichte, University of Freiburg Faculty of Biology This article is based on a translation of the equivalent article at the German Wikipedia. In, Leopoldina — On line, part 1, 1871–1872, rede bei der Enthüllung des Denkmals von Alexander Braun,1879 Braun, Alexander
Alexander Braun
–
Alexander Braun
40.
Double flower
–
Double-flowered describes varieties of flowers with extra petals, often containing flowers within flowers. The double-flowered trait is often noted alongside the name with the abbreviation fl. pl. The first abnormality to be documented in flowers, double flowers are popular varieties of many flower types, including roses, camellias. In some double-flowered varieties all of the organs are converted to petals — as a result, they are sexually sterile. Many double-flowered plants have little value as access to the nectaries is typically blocked by the mutation. Double flowers are the earliest documented form of floral abnormality, first recognized more than two years ago. Theophrastus mentioned double roses in his Enquiry into Plants, written before 286BC, pliny also described double roses in 1st century BC. In China, double peonies were known and selected by around 750AD, today, most cultivated rose varieties bear this double-flower trait. A double-flowered variety of Marsh Marigold was discovered and cultivated in Austria in the late 16th century, the first documented double-flowered mutant of Arabidopsis, a model organism for plant development and genetics, was recorded in 1873. Double-flower forms often arise when some or all of the stamens in a flower are replaced by petals and these types of mutations, where one organ in a developing organism is replaced with another, are known as homeotic mutations. They are usually recessive, although the double mutation in carnations exhibits incomplete dominance. When both copies of the gene are deleted or otherwise damaged, developing flowers lack the signals to form stamen, regions which would have formed stamens instead default to petals and the carpel region develops into a new flower, resulting in a recursive sepal-petal-petal pattern. Because no stamens and carpels form, the plants have no reproductive organs and are sexually sterile, mutations affecting flower morphology in Arabidopsis can be described by the ABC model of flower development. These genes are expressed in regions of the developing flower and are responsible for development of organs in those regions. Agamous is a C class gene, a transcription factor responsible for activating genes involved in stamen and carpel development
Double flower
–
A double-flowered cultivar of
Impatiens walleriana.
Double flower
–
Double-flowered Arabidopsis
Double flower
–
Most garden
roses are double-flowered
Double flower
–
Double-flowered
lilac, often called "French lilac"
41.
X-ray
–
X-radiation is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz, X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. Spelling of X-ray in the English language includes the variants x-ray, xray, X-rays with high photon energies are called hard X-rays, while those with lower energy are called soft X-rays. Due to their ability, hard X-rays are widely used to image the inside of objects, e. g. in medical radiography. The term X-ray is metonymically used to refer to an image produced using this method. Since the wavelengths of hard X-rays are similar to the size of atoms they are useful for determining crystal structures by X-ray crystallography. By contrast, soft X-rays are easily absorbed in air, the length of 600 eV X-rays in water is less than 1 micrometer. There is no consensus for a definition distinguishing between X-rays and gamma rays, one common practice is to distinguish between the two types of radiation based on their source, X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus. This definition has problems, other processes also can generate these high-energy photons. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m and this criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. Occasionally, one term or the other is used in specific contexts due to precedent, based on measurement technique. Thus, gamma-rays generated for medical and industrial uses, for radiotherapy, in the ranges of 6–20 MeV. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds and this makes it a type of ionizing radiation, and therefore harmful to living tissue. A very high radiation dose over a period of time causes radiation sickness. In medical imaging this increased risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be utilized in treatment to kill malignant cells using radiation therapy. It is also used for material characterization using X-ray spectroscopy, hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason, X-rays are widely used to image the inside of visually opaque objects, the most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry and research
X-ray
–
Spectrum of the X-rays emitted by an X-ray tube with a
rhodium target, operated at 60
kV. The smooth, continuous curve is due to
bremsstrahlung, and the spikes are
characteristic K lines for rhodium atoms.
X-ray
–
X-rays are part of the
electromagnetic spectrum, with wavelengths shorter than
visible light. Different applications use different parts of the X-ray spectrum.
X-ray
–
A
chest radiograph of a female, demonstrating a
hiatus hernia
X-ray
–
An arm radiograph, demonstrating broken
ulna and
radius with implanted
internal fixation.
42.
Mutagenesis
–
Mutagenesis /mjuːtəˈdʒɛnɪsɪs/ is a process by which the genetic information of an organism is changed, resulting in a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens and it can also be achieved experimentally using laboratory procedures. In nature mutagenesis can lead to cancer and various heritable diseases, mutagenesis as a science was developed based on work done by Hermann Muller, Charlotte Auerbach and J. M. Robson in the first half of the 20th century. DNA may be modified, either naturally or artificially, by a number of physical, chemical and biological agents and his contemporary Lewis Stadler also showed the mutational effect of X-ray on barley in 1928, and ultraviolet radiation on maize in 1936. In 1940s, Charlotte Auerbach and J. M. Robson, for example, soot was suggested to be a cause of cancer as early as 1775, and coal tar was demonstrated to cause cancer in 1915. The chemicals involved in both were shown to be polycyclic aromatic hydrocarbons. PAHs by themselves are not carcinogenic, and it was proposed in 1950 that the forms of PAHs are the oxides produced as metabolites from cellular processes. Mammalian nuclear DNA may sustain more than 60,000 damage episodes per cell per day, if left uncorrected, these adducts, after misreplication past the damaged sites, can give rise to mutations. In nature, the mutations that arise may be beneficial or deleterious — this is the force of evolution. An organism may acquire new traits through genetic mutation, but mutation may result in impaired function of the genes. Initially, the ability of radiation and chemical mutagens to cause mutation was exploited to generate random mutations, DNA damage is an abnormal alteration in the structure of DNA that cannot, itself, be replicated when DNA replicates. In contrast, a mutation is a change in the nucleic acid sequence that can be replicated, hence, damage can occur from chemical addition, or structural disruption to a base of DNA, or a break in one or both DNA strands. When DNA containing damage is replicated, a base may be inserted in the new complementary strand as it is being synthesized. The incorrect insertion in the new strand will occur opposite the site in the template strand. Furthermore, double-strand breaks in DNA may be repaired by a repair process, non-homologous end joining. Mutations can ordinarily be avoided if accurate DNA repair systems recognize DNA damage, at least 169 enzymes are either directly employed in DNA repair or influence DNA repair processes. Of these,83 are directly employed in the 5 types of DNA repair processes indicated in the shown in the article DNA repair. Mutagenesis may also arise as a result of the presence of mutagens that induce changes to the DNA
Mutagenesis
–
Ethidium intercalated between two adenine-thymine base pairs.
Mutagenesis
–
Arrows indicates chromosomal breakages due to DNA damage
43.
Ecotype
–
An ecotype is a variant in which the phenotypic differences are too few or too subtle to warrant being classified as a subspecies. These can occur in the geographic region where distinct habitats such as meadow, forest, swamp. Where similar ecological conditions occur in widely separated places it is possible for a similar ecotype to occur and this is different to a subspecies, which may exist across a number of different habitats. In animals, ecotypes can be regarded as micro-subspecies that owe their differing characteristics to the effects of a local environment. Therefore, ecotypes have no taxonomic rank, ecotypes are closely related to morphs. The frequency of these forms is too high to be explained by mutation. In order to be classified as such, morphs must occupy the same habitat at the same time, in fact, Begon, Townsend and Harper assert that The notions form and ecotype may appear to correspond to a static phenomenon, however this is not always the case. Evolution occurs continuously both in time and space, so that two ecotypes or forms may qualify as species in only a few generations. Begon, Townsend and Harper use an illuminating analogy on this, Thus ecotypes, experiments indicate that sometimes ecotypes manifest only when separated by great spatial distances. This is due to hybridization whereby different but adjacent varieties of the same species interbreed, however other studies reveal that the opposite may happen, i. e. ecotypes revealing at very small scales, within populations, and despite hybridization. In ecotypes, it is common for continuous, gradual geographic variation to impose analogous phenotypic and/or genetic variation, a well-known example of cline is the skin color gradation in indigenous human populations worldwide, which is related to latitude and amounts of sunlight. But often the distribution of ecotypes is bimodal or multimodal and this means that ecotypes may display two or more distinct and discontinuous phenotypes even within the same population. Such phenomenon may lead to speciation and can occur if conditions in a local environment change dramatically through space or time, earthworms fall into four different ecotypes. Compost earthworms prefer warm and moist environments with a supply of fresh compost material. Epigeic earthworms live on the surface of the soil in leaf litter and tend not to make burrows but live in and feed on the leaf litter. Endogeic earthworms live in and feed on the soil, making horizontal burrows through the soil to move around and to feed, anecic earthworms make permanent vertical burrows in soil, feeding on leaves on the soil surface that they drag into their burrows. Tundra reindeer and woodland reindeer are two ecotypes of reindeer, the first migrate annually between the two environments in large numbers whereas the other remain in the forest for the summer. In North America, the species Rangifer tarandus —the migratory George River Caribou Herd, arabis fecunda, a herb endemic to some calcareous soils of Montana, United States, can be divided into two ecotypes
Ecotype
–
Four different
ecotypes of
Physcomitrella patens, stored at the
International Moss Stock Center
Ecotype
–
Rangifer tarandus caribou, a member of the woodland ecotype.
Ecotype
–
General
Ecotype
–
Population ecology
44.
Maize
–
Maize, also known as corn, is a large grain plant first domesticated by indigenous peoples in Mexico about 10,000 years ago. The six major types of corn are dent corn, flint corn, pod corn, popcorn, flour corn, the leafy stalk of the plant produces separate pollen and ovuliferous inflorescences or ears, which are fruits, yielding kernels or seeds. Maize kernels are used in cooking as a starch. Most historians believe maize was domesticated in the Tehuacan Valley of Mexico, recent research modified this view somewhat, scholars now indicate the adjacent Balsas River Valley of south-central Mexico as the center of domestication. The Olmec and Mayans cultivated maize in numerous varieties throughout Mesoamerica, cooked and its believed that beginning about 2500 BC, the crop spread through much of the Americas. The region developed a network based on surplus and varieties of maize crops. Nevertheless, recent data indicates that the spread of maize took place even earlier, according to Piperno, A large corpus of data indicates that it was dispersed into lower Central America by 7600 BP and had moved into the inter-Andean valleys of Colombia between 7000 and 6000 BP. Since then, even earlier dates have been published, the study also demonstrated that the oldest surviving maize types are those of the Mexican highlands. Later, maize spread from this region over the Americas along two major paths and this is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands. Before they were domesticated, maize plants only grew small,25 millimetres long corn cobs, Maize is the most widely grown grain crop throughout the Americas, with 361 million metric tons grown in the United States in 2014. Approximately 40% of the crop—130 million tons—is used for corn ethanol, genetically modified maize made up 85% of the maize planted in the United States in 2009. After the arrival of Europeans in 1492, Spanish settlers consumed maize and explorers and traders carried it back to Europe, Spanish settlers far preferred wheat bread to maize, cassava, or potatoes. Maize flour could not be substituted for wheat for bread, since in Christian belief only wheat could undergo transubstantiation. At another level, Spaniards worried that by eating indigenous foods, which they did not consider nutritious, that not only would they weaken, despite these worries, Spaniards did consume maize and archeological evidence from Florida sites indicate they cultivated it as well. Maize spread to the rest of the world because of its ability to grow in diverse climates and it was cultivated in Spain just a few decades after Columbuss voyages and then spread to Italy, West Africa and elsewhere. The word maize derives from the Spanish form of the indigenous Taíno word for the plant and it is known by other names around the world. The word corn outside North America, Australia, and New Zealand refers to any cereal crop, in the United States, Canada, Australia, and New Zealand, corn primarily means maize, this usage started as a shortening of Indian corn. Indian corn primarily means maize, but can more specifically to multicolored flint corn used for decoration
Maize
–
Maize
Maize
–
A maize heap at the harvest site, India
Maize
–
Many small male flowers make up the male inflorescence, called the tassel.
Maize
–
Female inflorescence, with young
silk
45.
Petunia
–
The popular flower of the same name derived its epithet from the French, which took the word petun, meaning tobacco, from a Tupi–Guarani language. An annual, most of the varieties seen in gardens are hybrids, the plants are herbaceous, generally hairy, and the flowers are funnel-shaped, with petals joined together. The fruit is a dry capsule with two compartments and many tiny seeds, Petunia is a genus in the family Solanaceae, subfamily Petunioideae. Well known members of Solanaceae in other subfamilies include tobacco, some botanists place the plants of the genus Calibrachoa in the genus Petunia, but this is not accepted by others. Petchoa is a hybrid derived from crossing Calibrachoa and Petunia. Petunias are generally insect pollinated, with the exception of P. exserta, most petunias are diploid with 14 chromosomes and are interfertile with other petunia species. The tubular flowers are favoured by some Lepidoptera species, including the Hummingbird hawk moth, the flowers are eaten by the larvae of the corn earworm, Helicoverpa zea and the cabbage looper, Trichoplusia ni. Petunias can tolerate relatively harsh conditions and hot climates and they need at least five hours of sunlight every day. They grow well in low humidity, moist soil, young plants can be grown from seeds. In drier regions, the plants should be watered daily, maximum growth occurs in late spring. Applying fertilizer monthly or weekly, depending on the variety, will help the plant grow quickly, petunias can be cultivated in hanging baskets. In horticulture many terms are used to different types of cultivated petunias. These include Grandiflora, Multiflora, Wave, Supertunia, Cascadia, many species other than P. × atkinsiana are also gaining popularity in the home garden
Petunia
–
Petunia
Petunia
–
Flower pot planted with petunias
Petunia
–
A form of
Petunia axillaris
Petunia
–
White
Petunia axillaris
46.
Tobacco
–
Tobacco is a product prepared from the leaves of the tobacco plant by curing them. The plant is part of the genus Nicotiana and of the Solanaceae family, while more than 70 species of tobacco are known, the chief commercial crop is N. tabacum. The more potent variant N. rustica is also used around the world, Tobacco contains the alkaloid nicotine, which is a stimulant. Dried tobacco leaves are used for smoking in cigarettes, cigars, pipe tobacco. They can be consumed as snuff, chewing tobacco, dipping tobacco. Tobacco use is a factor for many diseases, especially those affecting the heart, liver. In 2008, the World Health Organization named tobacco as the single greatest preventable cause of death. The English word tobacco originates from the Spanish and Portuguese word tabaco, the precise origin of this word is disputed, but it is generally thought to have derived at least in part, from Taino, the Arawakan language of the Caribbean. In Taino, it was said to either a roll of tobacco leaves or to tabago. Tobacco has long used in the Americas, with some cultivation sites in Mexico dating back to 1400–1000 BC. Many Native American tribes have traditionally grown and used tobacco, traditionally, tobacco is seen as a gift from the Creator, with the ceremonial tobacco smoke carrying ones thoughts and prayers to the Creator. Following the arrival of the Europeans to the Americas, tobacco became popular as a trade item. Hernández de Boncalo, Spanish chronicler of the Indies, was the first European to bring seeds to the Old World in 1559 following orders of King Philip II of Spain. These seeds were planted in the outskirts of Toledo, more specifically in a known as Los Cigarrales named after the continuous plagues of cicadas. Before the development of lighter Virginia and white burley strains of tobacco, small quantities were smoked at a time, using a pipe like the midwakh or kiseru or smoking newly invented waterpipes such as the bong or the hookah. The alleged benefits of tobacco also account for its considerable success, Tobacco smoking, chewing, and snuffing became a major industry in Europe and its colonies by 1700. Tobacco has been a major crop in Cuba and in other parts of the Caribbean since the 18th century. In the late 19th century, cigarettes became popular, James Bonsack created a machine that automated cigarette production
Tobacco
–
Tobacco can also be pressed into plugs and sliced into flakes.
Tobacco
–
A historic kiln in
Myrtleford, Victoria, Australia
Tobacco
–
Basma tobacco leaves drying in the sun at
Pomak village in
Xanthi, Greece
Tobacco
–
William Michael Harnett (American, 1848-1892), Still Life with Three Castles Tobacco, 1880,
Brooklyn Museum
47.
Transfer DNA
–
The transfer DNA is the transferred DNA of the tumor-inducing plasmid of some species of bacteria such as Agrobacterium tumefaciens and Agrobacterium rhizogenes. The T-DNA is transferred from bacterium into the host plants nuclear DNA genome, the T-DNA is bordered by 25-base-pair repeats on each end. Transfer is initiated at the border and terminated at the left border. The bacterial T-DNA is about 24,000 base pairs long, by transferring the T-DNA into the plant genome, the bacterium essentially reprograms the plant cells to grow into a tumor and produce a unique food source for the bacteria. The synthesis of the plant hormones auxin and cytokinin enables the plant cell to grow uncontrollably, the opines are amino acid derivatives used by the bacterium as a source of carbon and energy. Agrobacterium-mediated T-DNA transfer is used as a tool in biotechnology. Examples of selection markers include neomycin phosphotransferase, hygromycin B phosphotransferase, Agrobacterium is then used as a vector to transfer the engineered T-DNA into the plant cells where it integrates into the plant genome. This method can be used to generate transgenic plants carrying a foreign gene, the first step in integrating the T-DNA into a host genome is the formation of a nick at the right border of the Ti plasmid. This nick creates a region of single stranded DNA from the border of the T-DNA gene over to the right border which was cut. Single stranded binding proteins then attach to the single stranded DNA, DNA synthesis will displace the single stranded region and then a second nick at the left border region will release the single stranded T-DNA fragment. This fragment can then be incorporated into a host genome, the same procedure of T-DNA transfer can be used to disrupt genes via insertional mutagenesis. Not only does the inserted T-DNA sequence create a mutation but it also tags the affected gene and this method is used widely to study gene function in plants, such as the model plant Arabidopsis thaliana. Eichhorn, Biology of Plants, 7th Edition, W. H. Freeman and Company Publishers, New York, ISBN 0-7167-1007-2
Transfer DNA
–
Ti plasmid with T-DNA region
48.
Transformation (genetics)
–
Transformation is one of three processes for horizontal gene transfer, in which exogenous genetic material passes from bacterium to another, the other two being conjugation and transduction. In transformation, the material passes through the intervening medium. Transformation in bacteria was first demonstrated in 1928 by British bacteriologist Frederick Griffith, Griffith discovered that a strain of Streptococcus pneumoniae could be made virulent after being exposed to heat-killed virulent strains. Griffith hypothesized that some transforming principle from the strain was responsible for making the harmless strain virulent. In 1944 this transforming principle was identified as being genetic by Oswald Avery, Colin MacLeod and they isolated DNA from a virulent strain of S. pneumoniae and using just this DNA were able to make a harmless strain virulent. They called this uptake and incorporation of DNA by bacteria transformation, the results of Avery et al. It was originally thought that Escherichia coli, a used laboratory organism, was refractory to transformation. However, in 1970, Morton Mandel and Akiko Higa showed that E. coli may be induced to take up DNA from bacteriophage λ without the use of helper phage after treatment with calcium chloride solution. Two years later in 1972, Stanley Norman Cohen, Annie Chang, the method of transformation by Mandel and Higa was later improved upon by Douglas Hanahan. Transformation of animal and plant cells was also investigated with the first transgenic mouse being created by injecting a gene for a rat growth hormone into an embryo in 1982. In 1907 a bacterium that caused plant tumors, Agrobacterium tumefaciens, was discovered, not all plant cells are susceptible to infection by A. tumefaciens, so other methods were developed, including electroporation and micro-injection. Particle bombardment was possible with the invention of the Biolistic Particle Delivery System by John Sanford in the 1980s. In transformation, the material passes through the intervening medium. Competence refers to a state of being able to take up exogenous DNA from the environment. Natural genetic transformation appears to be an adaptation for repair of DNA damage that also generates genetic diversity and it has also been reported in at least 30 species of Proteobacteria distributed in the classes alpha, beta, gamma and epsilon. Naturally competent bacteria carry sets of genes that provide the protein machinery to bring DNA across the cell membrane, the DNA first binds to the surface of the competent cells on a DNA receptor, and passes through the cytoplasmic membrane via DNA translocase. Only single-stranded DNA may pass through, the other strand being degraded by nucleases in the process, the translocated single-stranded DNA may then be integrated into the bacterial chromosomes by a RecA-dependent process. In Gram-negative cells, due to the presence of an extra membrane, pilin may be required for competence, but its role is uncertain
Transformation (genetics)
–
In this image, a gene from bacterial cell 1 is moved from bacterial cell 1 to bacterial cell 2. This process of bacterial cell 2 taking up new genetic material is called transformation.
_lehekarv_(trihhoom)_311_0804.JPG)
. PMID 25807084. doi:10.7554/eLife.06100. Retrieved 2017-04-20.
