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How Many Species of Plants Are There

postman1 — Sat, 03 Sep 2011 11:03:54 +0000

There are about 375,000 species of plants, with more being discovered each year. This includes seed plants, bryophytes, ferns and relatives of ferns called fern allies. Some 297,326 species of plants have been identified, of which 258,650 are flowering and 15,000 bryophytes (liverworts, hornworts, and mosses). All plants are photosynthetic, utilizing carbon dioxide, water and light energy to produce oxygen and sugars. Within each cell are numerous organelles called chloroplasts which perform this task. Chloroplasts are thought to be ancient cyanobacteria that were absorbed by the larger eukaryotic cells which constitute plants.

Plants consist of two main groups; green algae and land plants. Other types of algae, such as red algae and brown algae, were initially identified as plants, but later classified outside the kingdom Plantae. These latter organisms are part of the same unranked group as plants, Archaeplastida, but are usually not referred to as plants except in a colloquial sense. An example of a familiar green algae is seaweed.

Most plants, of course, are the land plants, known as embryophytes. The most common are the vascular plants, meaning they have internal tubes to carry water and nutrients. The minority are species of plants called bryophytes, including liverworts, hornworts, and mosses. Without vascular tubes, plants can only grow a couple inches tall. Bryophytes first evolved during the Cambrian era, about 500 million years ago, and have remained abundant ever since.

The vascular plants are a more advanced species of plant. These evolved during the Silurian era, about 420 million years ago, and went on to dominate the land, both in terms of diversity and biomass. Vascular plants are the keystone that holds up the entire terrestrial ecosystem, in the same way that cyanobacteria hold up the ecosystem in the oceans.

The first serious innovation after the initial evolution of vascular plants was that of the seed. Using seeds, plants could colonize drier areas than before, and survive seasonal drought. By comparison, plants that reproduce via spores, such as ferns, require a moist environment.

The most recent plants to evolve were the angiosperms, or flowering plants. These developed only 125 million years ago, during the Cretaceous. The point of evolving flowers was to get mobile animals, especially insects, involved in the process of exchanging pollen and therefore genetic material.

How Many Left-Handed Presidents Has the US Had

postman1 — Sat, 03 Sep 2011 11:00:42 +0000

As of 2008, the United States has had seven left-handed Presidents in its history, and since both the Republican and Democratic nominees for President in 2008 were left-handed, the number is slated to become eight. Incidentally, only two of those Presidents have been Democratic, for those who were planning on making cracks about being on the “left.”

In chronological order, the left-handed Presidents are: James Garfield (1881), Herbert Hoover (1929-1933), Harry Truman (1945-1953), Gerald Ford (1974-1977), Ronald Reagan (1981-1989), George Bush Sr. (1989-1993), and Bill Clinton (1993-2001). It is intriguing to note that the United States was in the control of a southpaw for 20 years from 1981-2001, considering how rare left-handed people are in the general population.

There are some disputes about the list of left-handed Presidents. Prior to the 20th century, left-handedness was regarded as a negative character trait, and it is possible that more presidents prior to the 20th century were left-handed, but they concealed that fact. “Retraining” of left-handed individuals was also very common well through the 20th century, with young children being forced to write with their right hands, even if their left hands were dominant.

For those interested in Presidential trivia, two of the left-handed Presidents, Garfield and Reagan, experienced assassination attempts. Garfield probably would have survived with the benefit of modern medicine, but he had the misfortune to be shot in 1881, dying only after weeks of infection and misery. Reagan survived, as the bullet barely missed his heart. Truman and Ford were both Vice-Presidents who succeeded to the office of the Presidency, after the death of President Roosevelt in 1945 and the resignation of President Nixon in 1974. Ford was the only President who never won a national election, as he was appointed to the office of the Vice-Presidency after Nixon’s original running mate resigned from the office in disgrace.

Hoover is sometimes left off lists of left-handed Presidents, making his left-handed status unclear, and Reagan started out left-handed as a child, but later learned to write with this right hand, making his inclusion questionable as well. Given that an estimated seven to 10 percent of the population is left-handed, eight of 44 Presidents is a pretty remarkable statistic, and a cause for pride among some members of the left-handed community. Left-handed individuals are supposedly more creative and articulate than their right-handed counterparts, due to differences in brain function which have been explored in numerous studies, and this may have something to do with the high number of left-handed Presidents

How Many Muscles Are Used to Smile

postman1 — Sat, 03 Sep 2011 10:58:59 +0000

Many people have heard some version of the saying “it takes X muscles to frown, but only Y muscles to smile,” with X usually being larger than Y, to suggest that it should be easier to smile than frown. The numbers in this saying can vary quite radically, however, and even when one accounts for the different types of smiles, such diversity is a bit suspect; any number between four and 22 seems to be used. In fact, the precise number of muscles used to smile is a bit unclear, although people have certainly conducted extensive research into the matter.

Of the 36 muscles used to create facial expressions, only a fraction are used in smiling. The precise number involved can vary, depending on an assortment of factors. Some people, for example, argue that eye crinkles are part of a genuine smile, and that therefore the muscles involved in this activity should be considered part of the number of muscles required to smile. Researchers have also discovered that people from different areas of the world smile differently, although they may use many of the same muscles.

Different types of smiles have also been extensively documented, ranging from the zygomatic or genuine to the utterly fake. People make smile-like expressions for a variety of reasons and in an assortment of ways, and each requires slightly different muscle movements. By studying pictures of people smiling, some skilled researchers can point out the subtle meaning and variation behind the seemingly friendly facial expression.

Six pairs of muscles appear to be directly involved in smiling: the levator anguli oris, levator labii superioris, orbicularis oculi, risorius, zygomaticus major, and zygomaticus minor. This brings the grand total to 12 muscles most probably used to smile. Most authorities who are familiar with their anatomy seem to settle on this number, with 11 muscles being used to frown. That’s right: in terms of sheer numbers of muscles involved, it is theoretically easier to frown than to smile.

Before one rushes to dispute the saying that it is easier to smile than frown based on this evidence, it is important to be aware that in its resting state, the mouth often approaches a smiling expression, suggesting that minimal effort is required to pull the mouth into a full grin. Furthermore, muscles vary widely in size and strength, so it is entirely possible that people expend less energy in smiling than they do in frowning. Perhaps some intrepid researcher will conduct a detailed study to get to the bottom of the matter.

How Many US Presidents Served More than One Term as President

postman1 — Sat, 03 Sep 2011 10:56:50 +0000

The simple answer to this question is that almost half of the United States presidents to date have served more than one term as president. In fact, 20 presidents in all have served more than one full term in office. They were: Franklin D. Roosevelt, Thomas Jefferson, James Madison, James Monroe, Andrew Jackson, Ulysses S. Grant, Grover Cleveland, Woodrow Wilson, Dwight D. Eisenhower, Ronald Reagan, Bill Clinton, George Washington, Harry Truman, George W. Bush, Theodore Roosevelt, Calvin Coolidge, Richard M. Nixon, Lyndon B. Johnson, William McKinley and Abraham Lincoln.

Franklin Delano Roosevelt (FDR) is the only us president in history that served more than two terms in office. In fact, FDR was elected to 4 full terms in office. Unfortunately Roosevelt died during his 4th term and the remainder of the term was served by his Vice President, Harry S Truman.

In 1947 the Twenty-Second Amendment of the United States Constitution was passed. This amendment stated that a President cannot serve more than 10 years or two consecutive terms in office.

However, not every us President that served more than one term served them consecutively. Grover Cleveland was the only president that served two terms that were not in a row. Cleveland goes down in the American history books as both the 22nd and 24th President of the USA

Out of the 20 us presidents that served more than one term as president, 11 individuals served two full terms. These presidents included: Thomas Jefferson, James Madison, James Monroe, Andrew Jackson, Ulysses S. Grant, Woodrow Wilson, Dwight D. Eisenhower, Ronald Reagan, Bill Clinton, George Washington and George W. Bush.

There are also a handful of leaders that were originally elected as a Vice President and ended up serving part of a previous President’s term. Of these leaders 4 went on to be elected to their own term. This President’s include Harry Truman, Theodore Roosevelt, Calvin Coolidge and Lyndon B. Johnson.

These US presidents are not the only American leaders who served more than one term but less than two terms. Richard Nixon resigned during his second term after the Watergate scandal, while William McKinley and Abraham Lincoln were both assassinated during their second terms in the presidential office.

How Many Species of Insect Are There

postman1 — Sat, 03 Sep 2011 10:53:48 +0000

Insects are the most diverse group of animals on Earth. There are over a million described species of insect, and an estimated 6-10 million species total. Insects are found in nearly every above-ground environment, even in Antarctica, which has a species of insect called springtails. There is even a species of insect that lives on the surface of the open ocean, walking on the water tension using tiny leg hairs. These are insects of the genus Halobates, otherwise known as sea skaters or water striders. Around Antarctica, where there is greater oxygen in the sea than the Equator, these can grow to 30 cm (1 ft) in width.

So far, there have been observations of 5,000 dragonfly species, 2,000 praying mantis, 20,000 grasshopper, 170,000 butterfly and moth, 120,000 fly, 82,000 true bug, 360,000 beetle, and 110,000 bee, wasp and ant species. Keep in mind that arachnids, such as mites — of which there are over 1 million described species — and crustaceans, like lobsters, are not insects, which only includes members of the class Insecta.

Species of insect range in size from 0.139 mm (0.00547 in, fairyfly) to 55.5 cm (21.9 in, stick insect), with most falling between 0.5 mm (0.02 in) and 50 mm (2 in). In general, smaller insects are capable of reproducing more rapidly due to their larger counterparts, allowing them to maintain their biomass over generations. If the biomass is not regularly replenished, then a species will go extinct. It is thought that the species of insect alive today only represent about 1% of all insects that have ever lived.

Insects are truly a success story for animals. Although most people don’t think of insects when the word “animal” is mentioned, they are both the most successful and numerous. The global insect biomass is estimated at 1012 kg, with approximately 1018 distinct individuals. Divided by the total number of species, this gives an average of 100 million individuals per species. Of course, like with other animals, the majority (over 66%) of insect species are found in the world’s rainforests.

How Many Tectonic Plates are There

postman1 — Sat, 03 Sep 2011 10:44:44 +0000

Tectonic plates are great slabs of rock which form the Earth’s crust. Both the continents and the oceans rest on tectonic plates, which float on the superheated, plastic mantle below. Over millions of years, these tectonic plates float around, driven by convection currents in the mantle, gathering into supercontinents and scattering again. This is called the theory of plate tectonics. Tectonic plates move about as fast as your fingernails grow — 5 to 10 centimeters per year.

The Earth has 14 major tectonic plates, and 38 minor plates, for 52 plates total. The major plates are the African Plate, Antarctic Plate, Arabian Plate, Australian Plate, Caribbean Plate, Cocos Plate, Eurasian Plate, Indian Plate, Juan de Fuca Plate, Nazca Plate, North American Plate, Pacific Plate, Philippine Plate, Scotia Plate, South American Plate. The largest are the Antarctic Plate, the Eurasian Plate, and the North American Plate. A continent may include several different plates: for instance, India and Arabia are both separate from the Eurasian Plate. The Himayala Mountains are a result of the Indian Plate pushing north into the Eurasian Plate.

Minor plates break off major plates during rifting events. Some minor plates subduct under other plates as they move. This causes them to be pushed down into the mantle and melt. The Farallon Plate to the west of San Francisco is almost completely subducted beneath the North American Plate, for example. Sometimes a part of a plate will end up on top of another plate, in which case it will be called an accreted terrane. Parts of North America and Europe are terranes.

It is thought that the boundaries of tectonic plates are partially determined by upwelling events called mantle plumes. These split apart the crust and cause it to crack, creating rifts, like the Red Sea, which separates Africa from Arabia. A typical upwelling event creates three rifts at roughly 120° from each other. This is called a triple junction. Usually, two of these rifts will continue to spread while one fails. A failed rift on land is called a rift valley.

How Many Neurotransmitters are There

postman1 — Sat, 03 Sep 2011 10:36:53 +0000

A neurotransmitter is a specialized messenger chemical that transfers or sends information from one type of cell to another. Scientists have managed to identify over 100 neurotransmitters in the human brain alone, but evidence suggests we have significantly more than this number. An unfortunate aspect of not being able to identify all neurotransmitter cells is that researchers, especially those developing medications to act on specific messenger cells, can’t always determine why or how medications work or fail to work.

You’re probably familiar with some of the identified neurotransmitter names. These include dopamine, GABA, serotonin, acetylcholine, and norepinephrine. Each of these performs some specific functions in the body. For instance serotonin is indicated in mood stability, emotional response, and temperature control. Acetylcholine is a neurotransmitter that allows for the person to willfully or voluntarily use his or her muscles. While researchers can suggest the possible effects of certain neurotransmitters, they not only haven’t identified them all, but also are nowhere near determining all effects of the messenger cells that have been identified

This is made very clear when people are given medications that should have an effect on a neurotransmitter. A variety of drugs focus on preventing the body from using serotonin too quickly and are called selective serotonin reuptake inhibitors (SSRIs). SSRIs are most commonly used to treat depression, and are helpful in preventing the body from using serotonin too quickly. When this neurotransmitter is in greater supply in the brain it tends to elevate mood, and you’ve likely heard the names of some of the common SSRIs like Prozac®, Zoloft® and Paxil®.

Theoretically, if serotonin were the only neurotransmitter responsible for depression, these medications would treat everyone. Yet many people with depression don’t respond to SSRIs. They may instead respond to medications that act on GABA, dopamine or norepinephrine. Some people have tried all these medications meant to alleviate depression and are still unresponsive to treatment. Failure to respond to treatment suggests we don’t fully understand the role of neurotransmitters in depression, and there may be unidentified messengers that create conditions like depressed or anxious states.

Since we don’t understand the precise mechanism of each neurotransmitter or the true number of all that exist, we also can’t understand how medications, foods, or environmental exposure may affect these chemical messengers. Scientists and researchers must make educated guesses based on what is known, but the plethora of unknown information on these cells equates these theories to trying to playing darts in total darkness. Sometimes the guesses are pretty good; SSRIs for instance are reasonably effective for a lot of people. Other times these theories fail to work, since we’re guessing about what is essentially undiscovered territory, and we have no idea what other effects might be caused by raising or decreasing levels of certain chemicals made by the body.

The mechanism and identification of neurotransmitters remains a fertile area of study in the sciences. If we could know precisely how many of these messengers we have, and exactly how they work, interact with each other, and drive the body, we might be able to effectively develop medications to treat numerous conditions. Until then, educated guesswork is relied upon by science and medicine.

How Many Species of Bacteria Are There

postman1 — Sun, 24 Apr 2011 20:32:00 +0000

Estimating the exact number of species of bacteria is impossible with today’s technology. To really move close to having an objective number, you’d have to have a machine that could process soil, water, and rock in large amounts, isolate the bacteria from their habitat, then sequence the genomes of as many bacteria as possible within the sample.
Today, given that sequencing a bacterial genome costs half a million dollars and takes a few months, this is infeasible. Even if costs fall by a factor of a trillion, there are so many microbes in soil that categorizing them in this way would be prohibitively expensive.
Instead of sequencing entire genomes, bacterial surveys today merely use snippets to distinguish between different species. This is more cost-effective than whole genome sequencing. One survey found 20,000 species of bacteria in a liter of seawater.
Another approach to determining the quantity of species of bacteria in a sample is to use a technique called DNA reassociation. In DNA reassociation, scientists use chemicals to “unzip” the two strands of the double-helix in bacterial DNA, then mix them up. Compatible DNA strands will re-link up with one another. The longer the reassociation process takes, the more species of bacteria are present in the sample. These measurements of time can be used to estimate bacterial biodiversity in the ocean or soil.
When this technique was applied to a soil sample in the late 90s, a 16,000 species of bacteria were found. However, this technique included the assumption that the populations of different species of bacteria were approximately similar, which is now known to be false. An updated survey by Jason Gans found there to be about a million bacterial species per gram of soil. While only a few bacterial species dominate the soil, there is a huge amount of low-abundance species.
Another approach is to use mathematical models of species diversity curves to extrapolate the total number of species in a given sample from information about the abundance of a few top species. A 2002 paper by Curtis, Sloan, and Scannel, “Estimating prokaryotic biodiversity and its limits”, estimated the number of oceanic bacteria taxa at lower than 2 million, the number of soil taxa at least 4 million, and the number of atmospheric taxa at least 4 million. However, this study assumed that the bacterial diversity in a gram of soil was only 6,400 – 38,000 per g, much less than found in the DNA reassociation study.
Currently, estimates of the total number of species of bacteria range from about 10 million to a billion, but these estimates are tentative, and may be off by many orders of magnitude. By comparison, there are probably between 10 and 30 million species of animals, the vast majority of them insects. The number of scientifically recognized species of animals is about 1,250,000. There are almost 300,000 recognized species of plants.

How Many Languages are Spoken in Africa

postman1 — Sun, 24 Apr 2011 20:26:51 +0000

Determining the number of languages spoken in Africa can be complex mostly because it can be difficult to determine whether two languages are distinct or simply dialects of the same language. Still many agree that the number lies around 2,000. Some of the more common languages spoken in Africa include Hausa, Swahili, and Yoruba. Others, including Dahalo, Laal, and Shabo, are less common and only spoken by a few hundred people. While many of the African languages are quite unrelated to one another, the majority of the languages spoken in Africa fall into one of four language families: Afro-Asiatic, Khoisan, Niger-Congo, and Nilo-Saharan.
The Afro-Asiatic language family generally covers the languages spoken in North Africa, East Africa, and Southwest Africa. Nearly 400 languages spoken by over 250 million people are represented by this language family which is largely comprised of Semetic languages. Some Afro-Asiatic languages are Aramaic, Amharic, Arabic, Hausa, Hebrew, and Tigrinya. Also included in the Afro-Asiatic family are the now extinct lanuages of Akkadian and Ancient Egyptian — two languages considered to be the oldest in the world.
The Khoisan (or Khoesaan) languages are generally spoken in the southwestern part of Africa, namely Angola, Botswana, and Namibia. What is probably most unique about the 50 or so Khoisan languages is that they are tonal and use clicking sounds. The largest Khoisan language is Nama which is spoken in Namibia. Other Khoisan languages include Haillom (Namibia) and Sandawe (Tanzania). The Khoisan languages as a whole are generally thought to be dying out.
The Niger-Congo language family is comprised of the greatest number of languages spoken in Africa. This family has over 1500 languages and is spoken by more than 500 million people. In the 1950’s Joseph Greenberg, a linguist and African anthropologist known for his work in language classification and typology, proposed that the Niger-Kordofanian language family join the Niger-Congo language family. Linguists commonly use the Niger-Congo to refer to the entire family, including Kordofanian as a sub-family. Some of the most common languages spoken in Africa that fall within this family include Igbo (Nigeria), Swahili (Tanzania), Yoruba (Nigeria), and Zulu (South Africa).
Approximately 200 languages fall into the Nilo-Saharan language family, and well over 10 million Africans speak a language within this family. Nilo-Saharan languages are mainly confined to the center of Africa and is represented by over 15 nations including Burkina Faso, Egypt, Kenya, Niger, Nigeria, Sudan, Tanzania, and Uganda. Some of the major Nilo-Saharan languages include Dinka (Sudan), Kanuri (Nigeria), and Luo or Dholuo (Kenya).
These languages spoken in Africa are considered to be official languages of the African Union (AU). Still, many of them are dying out to more widely used languages such as Arabic and Swahili. Recently, however, African countries are becoming more conscious about the value of their linguistic inheritance.

How Many Elements on the Periodic Table of the Elements Occur Naturally

postman1 — Sun, 24 Apr 2011 16:29:14 +0000

The answer to the question of how many objects on the periodic table of the elements are naturally occurring is actually a bit complicated. Conventional wisdom says that the first 92 elements, from element one, hydrogen, to element 92, uranium, are all naturally occurring, but in fact some of these elements are highly unstable, and have only been observed when they have been created artificially. Some people believe that elements 93 (neptunium) and 94 (plutonium) should also be included on a list of naturally occurring elements. As a result, anywhere between 94 and 88 elements are “naturally occurring,” depending on the definition one is using.
Elements are considered to be “naturally occurring” when they can be found in nature, rather than needing to be created in a laboratory, and many representations of the periodic table of the elements include a dividing line between natural and artificially produced elements. Some naturally occurring elements have very unstable isotopes or short half-lives, so they exist only intermittently and in very small quantities on Earth. Some people believe that when thinking about the periodic table of the elements, elements such as these should not really be considered “naturally occurring,” especially since they are only observed as a direct result of human activity. Others argue that while only small amounts are observable at any given time, they are “natural” because they can occur spontaneously.
The questionable elements are: element 43, technetium; element 61, promethium; element 85, astatine; and element 87, francium. Elements 43 and 61 are somewhat unusual, as they are surrounded by stable elements, but they have only been observed in controlled laboratory conditions. Elements 85 and 87 do appear in nature, but only briefly, and very rarely, making it tough to pin down an actual natural appearance for these shy members of the periodic table of the elements.
If all four questionable elements are struck from the list of “naturally occurring” elements, you end up with either 90 or 88 naturally occurring elements, depending on whether or not you think neptunium and plutonium belong on the list. Some people include astatine and francium on the list of naturally occurring elements, raising the total to 92 or 90. The most-commonly cited number is “92,” which could be viewed as the first 92 entries on the periodic table of the elements, or the first 94 minus elements 43 and 61, depending on how complicated you feel like being.
It it is important to remember that when looking at the periodic table of the elements, “naturally occurring” does not necessarily mean “abundant.” Many naturally occurring elements are in fact quite rare, although some were once more abundant. Levels of elements also change depending on where you are: helium, for example, is rare on Earth, but abundant around the Sun.