1.
Northern Hemisphere
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The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined as being in the celestial hemisphere relative to the invariable plane of the solar system as Earths North pole. Due to the Earths axial tilt, winter in the Northern Hemisphere lasts from the December solstice to the March Equinox, the dates vary each year due to the difference between the calendar year and the astronomical year. Its surface is 60. 7% water, compared with 80. 9% water in the case of the Southern Hemisphere, the Arctic is the region north of the Arctic Circle. Its climate is characterized by cold winters and cool summers, precipitation mostly comes in the form of snow. The Arctic experiences some days in summer when the Sun never sets, the duration of these phases varies from one day for locations right on the Arctic Circle to several months near the North Pole, which is the middle of the Northern Hemisphere. Between the Arctic Circle and the Tropic of Cancer lies the Northern Temperate Zone, the changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather, tropical regions are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during the winter months. In the Northern Hemisphere, objects moving across or above the surface of the Earth tend to turn to the right because of the coriolis effect, as a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres. These are best seen in circulation patterns in the North Atlantic. For the same reason, flows of air down toward the surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere, conversely, air rising from the northern surface of the Earth tends to draw air toward it in a counterclockwise pattern. Hurricanes and tropical storms spin counter-clockwise in the Northern Hemisphere, the shadow of a sundial moves clockwise in the Northern Hemisphere. When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere, the North Pole faces away from the galactic center of the Milky Way. The Northern Hemisphere is home to approximately 6.57 billion people which is around 90% of the total human population of 7.3 billion people
2.
Agriculture
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Agriculture is the cultivation and breeding of animals, plants and fungi for food, fiber, biofuel, medicinal plants and other products used to sustain and enhance human life. Agriculture was the key development in the rise of human civilization. The study of agriculture is known as agricultural science, the history of agriculture dates back thousands of years, and its development has been driven and defined by greatly different climates, cultures, and technologies. Industrial agriculture based on large-scale monoculture farming has become the dominant agricultural methodology, genetically modified organisms are an increasing component of agriculture, although they are banned in several countries. Agricultural food production and water management are increasingly becoming global issues that are fostering debate on a number of fronts, the major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. Specific foods include cereals, vegetables, fruits, oils, meats, fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo, other useful materials are also produced by plants, such as resins, dyes, drugs, perfumes, biofuels and ornamental products such as cut flowers and nursery plants. The word agriculture is a late Middle English adaptation of Latin agricultūra, from ager, field, Agriculture usually refers to human activities, although it is also observed in certain species of ant, termite and ambrosia beetle. To practice agriculture means to use resources to produce commodities which maintain life, including food, fiber, forest products, horticultural crops. This definition includes arable farming or agronomy, and horticulture, all terms for the growing of plants, even then, it is acknowledged that there is a large amount of knowledge transfer and overlap between silviculture and agriculture. In traditional farming, the two are often combined even on small landholdings, leading to the term agroforestry, Agriculture began independently in different parts of the globe, and included a diverse range of taxa. At least 11 separate regions of the Old and New World were involved as independent centers of origin, wild grains were collected and eaten from at least 105,000 years ago. Pigs were domesticated in Mesopotamia around 15,000 years ago, rice was domesticated in China between 13,500 and 8,200 years ago, followed by mung, soy and azuki beans. Sheep were domesticated in Mesopotamia between 13,000 and 11,000 years ago. From around 11,500 years ago, the eight Neolithic founder crops, emmer and einkorn wheat, hulled barley, peas, lentils, bitter vetch, chick peas and flax were cultivated in the Levant. Cattle were domesticated from the aurochs in the areas of modern Turkey. In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, coca, llamas, alpacas, sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago, cotton was domesticated in Peru by 5,600 years ago, and was independently domesticated in Eurasia at an unknown time
3.
Population
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A population is the number of all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding. In sociology, population refers to a collection of humans, Demography is a social science which entails the statistical study of human populations. This article refers mainly to human population, in population genetics a sexual population is a set of organisms in which any pair of members can breed together. This means that they can regularly exchange gametes to produce normally-fertile offspring and this also implies that all members belong to the same species. If the gamodeme is very large, and all gene alleles are uniformly distributed by the gametes within it, however, there may be low frequencies of exchange with these neighbours. This may be viewed as the breaking up of a sexual population into smaller overlapping sexual populations. The overall rise in homozygosity is quantified by the inbreeding coefficient, note that all homozygotes are increased in frequency – both the deleterious and the desirable. The mean phenotype of the collection is lower than that of the panmictic original – which is known as inbreeding depression. It is most important to note, however, that some lines will be superior to the panmictic original, while some will be about the same. The probabilities of each can be estimated from those binomial equations, in plant and animal breeding, procedures have been developed which deliberately utilise the effects of dispersion. It can be shown that dispersion-assisted selection leads to the greatest genetic advance and this is so for both allogamous and autogamous gamodemes. In ecology, the population of a species in a certain area can be estimated using the Lincoln Index. As of todays date, the population is estimated by the United States Census Bureau to be 7.496 billion. The US Census Bureau estimates the 7 billion number was surpassed on 12 March 2012, according to papers published by the United States Census Bureau, the world population hit 6.5 billion on 24 February 2006. The United Nations Population Fund designated 12 October 1999 as the day on which world population reached 6 billion. This was about 12 years after world population reached 5 billion in 1987, the population of countries such as Nigeria, is not even known to the nearest million, so there is a considerable margin of error in such estimates. Researcher Carl Haub calculated that a total of over 100 billion people have probably been born in the last 2000 years, Population growth increased significantly as the Industrial Revolution gathered pace from 1700 onwards. In 2007 the United Nations Population Division projected that the population will likely surpass 10 billion in 2055
4.
Organism
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In biology, an organism is any contiguous living system, such as an animal, plant, fungus, protist, archaeon, or bacterium. All known types of organisms are capable of some degree of response to stimuli, reproduction, growth and development and homeostasis. An organism consists of one or more cells, when it has one cell it is known as an organism. Most unicellular organisms are of microscopic scale and are thus described as microorganisms. Humans are multicellular organisms composed of trillions of cells grouped into specialized tissues. An organism may be either a prokaryote or a eukaryote, prokaryotes are represented by two separate domains—bacteria and archaea. Eukaryotic organisms are characterized by the presence of a cell nucleus. Fungi, animals and plants are examples of kingdoms of organisms within the eukaryotes, estimates on the number of Earths current species range from 10 million to 14 million, of which only about 1.2 million have been documented. More than 99% of all species, amounting to five billion species. In 2016, a set of 355 genes from the last universal ancestor of all living organisms living was identified. The term organism first appeared in the English language in 1703 and it is directly related to the term organization. There is a tradition of defining organisms as self-organizing beings. An organism may be defined as an assembly of molecules functioning as a more or less stable whole that exhibits the properties of life. Dictionary definitions can be broad, using such as any living structure, such as a plant, animal, fungus or bacterium, capable of growth. Many definitions exclude viruses and possible man-made non-organic life forms, as viruses are dependent on the machinery of a host cell for reproduction. A superorganism is an organism consisting of individuals working together as a single functional or social unit. There has been controversy about the best way to define the organism, several contributions are responses to the suggestion that the category of organism may well not be adequate in biology. Viruses are not typically considered to be organisms because they are incapable of autonomous reproduction and this controversy is problematic because some cellular organisms are also incapable of independent survival and live as obligatory intracellular parasites
5.
Human
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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
6.
Extinction vortex
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Extinction vortices are a class of models through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. Developed by M. E. Gilpin and M. E. Soulé in their famous 1986 paper Minimum viable populations, Processes of species extinction, there are currently four classes of extinction vortices. The first two deal with factors that have an effect on the ecosystem or community level, such as disturbance, pollution. This event can make populations vulnerable to additional disturbances which will lead to decreases in population size. A prime example of this would be the disruption of sex ratios in an away from the species optimum. Within these fragments, local extinction rates increase which, through positive feedback and this vortex can result from biological invasion, resulting in large scale hybridization and outbreeding depression. Mutational meltdown Small population size Mullers ratchet
7.
Allee effect
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The Allee effect is a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness of a population or species. Although the concept of Allee effect had no title at the time, it was first described in the 1930s by its namesake, through experimental studies, Allee was able to demonstrate that goldfish grow more rapidly when there are more individuals within the tank. This led him to conclude that aggregation can improve the rate of individuals. The term Allee principle was introduced in the 1950s, a time when the field of ecology was heavily focused on the role of competition among and within species. In other words, individuals in a population would be better off there are fewer individuals around due to a limited amount of resources. However, the concept of the Allee effect introduced the idea that the reverse holds true when the density is low. Individuals within a species often require the assistance of another individual for more than simple reproductive reasons in order to persist, the most obvious example of this is observed in animals that hunt for prey or defend against predators as a group. The generally accepted definition of Allee effect is positive density dependence and it is sometimes referred to as undercrowding and it is analogous to depensation in the field of fishery sciences. Listed below are a few significant subcategories of the Allee effect used in the ecology literature, the component Allee effect is the positive relationship between any measurable component of individual fitness and population density. The demographic Allee effect is the relationship between the overall individual fitness and population density. For example, cooperative hunting and the ability to easily find mates. At low population density, these component Allee effects would add up to produce an overall demographic Allee effect, when population density reaches a high number, negative density dependence often offsets the component Allee effects through resource competition, thus erasing the demographic Allee effect. It is important to note that Allee effects might occur even at high density for some species. The strong Allee effect is a demographic Allee effect with a population size or density. The weak Allee effect is a demographic Allee effect without a population size or density. The distinction between the two terms is based on whether or not the population in question exhibits a critical size or density. A population exhibiting a weak Allee effect will possess a reduced per capita growth rate at lower density or size. However, even at low population size or density, the population will always exhibit a positive per capita growth rate
Macau (China)
Monaco
Singapore
Hong Kong (China)
Gibraltar (UK)[11]
Bahrain
Vatican City
Malta
Maldives
Bermuda (UK)
Bangladesh
Taiwan
South Korea
Rwanda
Haiti
India
Burundi
Belgium
Philippines
Japan
