About Water

Water (chemical formula: H₂O) is a transparent fluid which forms the world's streams, lakes, oceans and rain, and is the major constituent of the fluids of organisms. As a chemical compound, a water molecule contains one oxygen and two hydrogenatoms that are connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on Earth with its solid state, ice; and gaseous state, steam (water vapor). It also exists as snow, fog, dew and cloud.

Water covers 71% of the Earth's surface.^[1] It is vital for all known forms of life. On Earth, 96.5% of the planet's crust water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of ice and liquid water suspended in air), andprecipitation.^[2][3] Only 2.5% of this water is freshwater, and 98.8% of that water is in ice (excepting ice in clouds) andgroundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products.^[2] A greater quantity of water is found in the earth's interior.^[4]

Water on Earth moves continually through the water cycle of evaporation and transpiration (evapotranspiration),condensation, precipitation, and runoff, usually reaching the sea. Evaporation and transpiration contribute to the precipitation over land. Water used in the production of a good or service is known as virtual water.

Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation.^[5] There is a clear correlation between access to safe water and gross domestic product per capita.^[6] However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability.^[7] A report, issued in November 2009, suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.^[8] Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70% of the freshwater used by humans goes to agriculture.^[9]

About Trees

In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. In looser senses, the taller palms, the tree ferns, bananas and bamboos are also trees. Trees tend to be long-lived, some reaching several thousand years old. The tallest known tree, a coast redwood named Hyperion, stands 115.6 m (379 ft) high. Trees have been in existence for 370 million years. It is estimated that there are just over 3 trillion mature trees in the world.^[1]

A tree typically has many secondary branches supported clear of the ground by the trunk. This trunk typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark which serves as a protective barrier. Below the ground, the roots branch and spread out widely; they serve to anchor the tree and extract moisture and nutrients from the soil. Above ground, the branches divide into smaller branches and shoots. The shoots typically bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development. Flowers and fruit may also be present, but some trees, such as conifers, instead have pollen cones and seed cones; others, such as tree ferns, produce spores instead.

Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from theatmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are one of the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture. Because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, and they play a role in many of the world's mythologies.

About Human

Modern humans (Homo sapiens, primarily ssp. Homo sapiens sapiens) are the only extant members of Hominina clade (or human clade), a branch of the taxonomical tribe Hominini belonging to the family of great apes. They are characterized byerect posture and bipedal locomotion; manual dexterity and increased tool use, compared to other animals; and a general trend toward larger, more complex brains and societies.^[3][4]

Early hominins—particularly the australopithecines, whose brains and anatomy are in many ways more similar to ancestral non-human apes—are less often referred to as "human" than hominins of the genus Homo.^[5] Several of these hominins used fire, occupied much of Eurasia, and gave rise to anatomically modern Homo sapiens in Africa about 200,000 years ago.^[6][7] 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 and populated most of the world.^[8]

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. Advantages that explain this evolutionary success include a relatively larger brainwith a particularly well-developed neocortex, prefrontal cortex and temporal lobes, which enable high levels of abstractreasoning, language, problem solving, sociality, and culture through social learning. Humans use tools to a much higher degree than any other animal, are the only extant species known to build fires and cook their food, and are the only extant species to clothe themselves and create and use numerous other technologies and arts.

Humans are uniquely adept at utilizing systems of symbolic communication (such as language and art) for self-expression and the exchange of ideas, and for organizing themselves into purposeful groups. Humans create complex social structurescomposed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established an extremely wide variety of values,^[9] social norms, and rituals, which together form the basis of human society. Curiosity and the human desire to understand and influence the environment and to explain and manipulate phenomena (or events) has provided the foundation for developing science, philosophy, mythology,religion, anthropology, and numerous other fields of knowledge.

Though most of human existence has been sustained by hunting and gathering in band societies,^[10] increasing numbers of human societies began to practice sedentary agriculture approximately some 10,000 years ago,^[11] domesticating plants and animals, thus allowing for the growth of civilization. These human societies subsequently expanded in size, establishing various forms of government, religion, and culture around the world, unifying people within regions to form states andempires. The rapid advancement of scientific and medical understanding in the 19th and 20th centuries led to the development of fuel-driven technologies and increased lifespans, causing the human population to rise exponentially. By 2014, the global human population was estimated to be around 7.2 billion and rising.^[12][13] By February 2016, the United States Census Bureauhad estimated that the world population had exceeded 7.3 billion.^[14]

About Mosquitoes

Mosquitoes are small, midge-like flies that constitute the family Culicidae. Females of most species are ectoparasites, whose tube-like mouthparts (called a proboscis) pierce the hosts' skin to consume blood. The word "mosquito" (formed by mosco anddiminutive -ito)^[2] is Spanish for "little fly".^[3] Thousands of species feed on the blood of various kinds of hosts, mainlyvertebrates, including mammals, birds, reptiles, amphibians, and even some kinds of fish. Some mosquitoes also attackinvertebrates, mainly arthropods. Though the loss of blood is seldom of any importance to the victim, the saliva of the mosquito often causes an irritating rash that is a serious nuisance. Much more serious though, are the roles of many species of mosquitoes as vectors of diseases. In passing from host to host, some transmit extremely harmful infections such as malaria,yellow fever, Chikungunya, West Nile virus, dengue fever, filariasis, Zika virus and other arboviruses, rendering it the deadliest animal family in the world.^[4][5][6]

About Ducks

Duck is the common name for a large number of species in the waterfowl family Anatidae, which also includes swans andgeese. The ducks are divided among several subfamilies in the family Anatidae; they do not represent a monophyletic group(the group of all descendants of a single common ancestral species) but a form taxon, since swans and geese are not considered ducks. Ducks are mostly aquatic birds, mostly smaller than the swans and geese, and may be found in both fresh water and sea water.

Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes,gallinules, and coots.

About Pandas

The giant panda (Ailuropoda melanoleuca, lit. "black and white cat-foot"; simplified Chinese: 大熊猫; traditional Chinese: 大熊貓; pinyin: dà xióng māo; Jyutping: daai6 hung4 maau1, lit. "big bear cat"),^[2] also known as panda bear or simply panda, is a bear^[3] native to south central China.^[1] It is easily recognized by the large, distinctive black patches around its eyes, over the ears, and across its round body. The name "giant panda" is sometimes used to distinguish it from the unrelated red panda. Though it belongs to the order Carnivora, the giant panda's diet is over 99% bamboo.^[4] Giant pandas in the wild will occasionally eat other grasses, wild tubers, or even meat in the form of birds, rodents or carrion. In captivity, they may receive honey, eggs, fish, yams, shrub leaves, oranges, or bananas along with specially prepared food.^[5][6]

The giant panda lives in a few mountain ranges in central China, mainly in Sichuan province, but also in neighbouring provinces, namely Shaanxi and Gansu.^[7] As a result of farming, deforestation, and other development, the giant panda has been driven out of the lowland areas where it once lived.

The giant panda is a conservation reliant endangered species.^[8] A 2007 report shows 239 pandas living in captivity inside China and another 27 outside the country.^[9] As of December 2014, 49 giant pandas live in captivity outside China, living in 18 zoos in 13 different countries.^[10] Wild population estimates vary; one estimate shows that there are about 1,590 individuals living in the wild,^[9] while a 2006 study via DNA analysis estimated that this figure could be as high as 2,000 to 3,000.^[11] Some reports also show that the number of giant pandas in the wild is on the rise.^[12] In March 2015, Mongabay stated the wild giant panda population increased by 268, or 16.8%, totaling to 1,864 individuals.^[13] However, the IUCN does not believe there is enough certainty yet to reclassify the species from endangered to vulnerable.^[1]

While the dragon has often served as China's national symbol, internationally the giant panda appears at least as commonly. As such, it is becoming widely used within China in international contexts, for example as one of the five Fuwamascots of the Beijing Olympics.

about bears

Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continentsof North America, South America, Europe, and Asia.

Common characteristics of modern bears include large bodies with stocky legs, long snouts, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. While the polar bear is mostly carnivorous, and the giant panda feeds almost entirely on bamboo, the remaining six species are omnivorous with varied diets.

With the exception of courting individuals and mothers with their young, bears are typically solitary animals. They are generally diurnal, but may be active during the night (nocturnal) or twilight (crepuscular), particularly around humans. Bears possess an excellent sense of smell and, despite their heavy build and awkward gait, are adept runners, climbers, and swimmers. In autumn, some bear species forage large amounts of fermented fruits, which affects their behavior.^[1] Bears use shelters, such as caves and burrows, as their dens; most species occupy their dens during the winter for a long period (up to 100 days) of sleep similar to hibernation.^[2]

Bears have been hunted since prehistoric times for their meat and fur. With their tremendous physical presence and charisma, they play a prominent role in the arts, mythology, and other cultural aspects of various human societies. In modern times, the bears' existence has been pressured through the encroachment on their habitats and the illegal trade of bears and bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing.