Sunday, March 16, 2014

Pollen or pollen (English ) is a tool for distributing

Pollen or pollen (English ) is a tool for distributing and generative reproduction of flowering plants . Pollen is a modification of the sperm cells . In cytology , pollen is a cell with three nuclei , each of which is called the vegetative nucleus , generative core I and core II generative . Cells in the pollen is protected by two layers ( called intine to the inside and the outer exine ) to prevent dehydration .
Pollen not survive long in the wild .
SariPollen powder itself is not the male gametes , [ 1 ] but each pollen grain contains vegetative ( non - reproductive ) cells ( only one cell in most flowering plants but several other plants ) and a generative ( reproductive ) cells containing two nuclei : a tube nucleus ( that produces the pollen tube ) and a generative nucleus ( that divides to
DAUNPOKER.NET AGEN POKER DOMINO ONLINE INDONESIA TERBAIK TERBESAR DAN TERPERCAYA form two sperm cells ) . A group of cells is surrounded by a cellulose -rich cell wall called the intine , and a resistant outer wall composed largely of sporopollenin called the exine .
Pollen is produced in microsporangium (contained in an Angiosperm flower anther , the male cone of a coniferous plant , or male cone of other plants ) . Pollen comes in many forms ( most often the ball ) , sizes , and surface markings characteristic of the species ( see electron micrographs in the upper right ) . Pollen of pine , spruce , and fir are winged . The smallest pollen grain , that of the Forget - me - not ( Myosotis spp . ) , Is about 6 lm ( 0,006 mm ) in diameter . The wind - borne pollen can be around 90-100 lm greater . [ 2 ] The study of pollen is called Palynology and very useful in Paleoecology , paleontology , archeology , and forensics .
In angiosperms , during flower development the anther is composed of a mass of cells that appear undifferentiated , except for partially differentiated dermis . Like the flower develops, four groups of sporogenous cells form in the anther , the fertile sporogenous cells are surrounded by a layer of sterile cells that grow into the wall of the pollen sac , some of the cells to grow into the cells that provide nutrients are nutrients for microspore formed by meiotic division from the sporogenous cell . Four haploid microspores are produced from each diploid sporogenous cell called microsporocyte , after meiotic division . After the formation of the four microspores , which are contained by callose walls , the development of pollen grain walls begins . Callose wall is broken down by an enzyme called callase and liberate pollen grew in size and shape characteristics develop and form a resistant outer wall called the exine and an inner wall called the intine . The exine is what is stored in the fossil record .
Pollen wall protects the sperm nucleus while the pollen grains from the anther to the stigma move , protect vital genetic material from dry and solar radiation . The surface of the pollen grain is covered with candles and protein , which is hel

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d in place by structures called sculpture elements on the surface of grains . Outer walls prevent pollen pollen grain from shrinking and destroying the genetic material during drying and consists of two layers . The second layer is the tectum and foot layer , which is just above the intine . Tectum and legs layers separated by an area called the columella , which consists of the reinforcement rods . The outer walls are built with resistant biopolymer called sporopollenin . The pollen tube passes through the wall of a structure called a hole . [ 3 ]
Pollen aperture is any modification of the wall of the pollen grain . The modifications include thinning , the mountains and the pores , they serve as a way out for the pollen contents and allow shrinking and swelling of wheat caused by changes in water content . Wrinkle in pollen grains called Colpi , which along with pores , are the main criteria for identifying pollen classes . [ 4 ]
Pollen may have wrinkles , orientation ( relative to the original tetrad of microspores ) classify the pollen as colpate or sulcate . The number of grooves or pores helps classify the flowering plants , with having three Colpi Magnoliopsida ( tricolpate ) , and other groups have one sulcus . [ 5 ] [ 6 ]
Except in the case of a plant submerged in water , the mature pollen - grain has a double wall , a thin delicate wall unchanged cellulose ( the endospore or intine ) and a tough outer exospore or exine cuticularized . Exine often bears spines or warts , or various sculptured , and the character of the signs often value for identifying genus , species , or even cultivation or individuals . In some plants flowering , seeding of pollen grains often begins before leaving microsporangium , the generative cell forming the two sperm cells . Pollination Main article : Pollination
Transfer pollen to the female reproductive structure ( pistil in angiosperms ) is called pollination . This transfer can be mediated by the wind , in this case the plant is described as anemophilous ( literally wind - loving ) . Anemophilous plants usually produce a large number of very lightweight pollen grains , sometimes with air bags . Non - flowering plants ( eg pine trees ) typical anemophilous . Anemophilous flowering plants generally have inconspicuous flowers . Entomophilous ( literally insect - loving ) plants produce pollen that is relatively heavy , sticky and protein -rich , for dissemination by insect pollinators attracted their interest . Many insects and some mites are specialized to feed on pollen, and called palynivores .
Non - flowering seed plants , pollen pollen germinates in the room , which is located beneath and inside the micropyle . A pollen tube is produced , which grows into the nucellus to provide nutrients for the development of sperm cells . Pinophyta sperm cells and Gnetophyta is without flagella , and carried by the pollen tube , whereas those Cycadophyta and Ginkgophyta have many flagella .
When placed on the stigma of a flowering pla
SayaPoker.com Agen Judi Poker dan Domino Online Terpercaya Indonesia nt , under favorable conditions , pollen grain puts forth a pollen tube which grows in the network style to the ovary, and makes its way along the placenta , guided by projections or hair , to the micropyle of the ovule . Core tube cell has meanwhile passed into the tube , as does also the generative nucleus which divides ( if not already ) to form two sperm cells . Sperm cells are carried to their destination at the end of the pollen - tube . Pollen as a carrier of information ecology of plants
A Russian theoretical biologist , Vigen Geodakyan ( Geodakian ) , has suggested that the amount of pollen reaching pistillate flower can transmit ecological information and also regulate evolutionary plasticity in cross-pollinating crops . Many pollen indicates optimum environmental conditions ( eg, a factory located in the middle of the natural range , in ideal growing conditions , with a large number of male plants nearby, and good weather conditions ) , while a small amount of pollen indicates extreme conditions ( on the border of the range, with a shortage of male plants , and adverse weather conditions ) . Geodakian believe that the amount of pollen reaching pistillate flower defines the sex ratio , dispersion and sexual dimorphism of the plant population . High pollen quantity leads to a decrease and stabilization characteristics of a population . The small amount of lead to their increase and destabilization of a population . [ 7 ]
The dependence of the secondary sex ratio in the amount of fertilizing pollen was confirmed on four dioecious plant species from three families - Rumex acetosa ( Polygonaceae ) , [ 8 ] [ 9 ] Melandrium album ( Cariophyllaceae ) , [ 10 ] [ 11 ] Cannabis sativa [ 12 ] and Humulus japonicus ( Cannabinaceae ) . [ 13 ] ( see a summary of all the data in the review article [ 14 ] ) .
Dependence on the number of offspring phenotype variety pollen was observed by Ter - Avanesyan in 1949 . All three studied species of plants ( cotton plant , black -eyed peas , and wheat ) showed dependence in the direction forecast by the theory - fertilization with a small amount of pollen resulted in an increase in the diversity of offspring . Ter - Avanesian wrote that as a result of limited pollination "instead of homogenous sorts of our population " . [ 15 ] [ 16 ] Pollen in the fossil record
Pollen 's sporopollenin outer layer affords it some resistance to the rigors of the fossilisation process that destroy weaker objects , but also produced in large quantities . Thus , there is an extensive fossil record of pollen , often broke away from the parent plant . Palynology discipline devoted to the study of pollen , which can be used both for biostratigraphy and to gain information about the abundance and diversity of plant life - which itself can yield important information about paleoclimates . Pollen is first found in the fossil record at the end of the Devonian period [ verification needed ] and an increase in abundance until now . Hay fever
Allergy to pollen is called hay fever. Generally pollens that cause allergies are of anemophilous plants ( pollen dispersed by air currents . ) Such plants produce large amounts of lightweight pollen ( because wind deployment at random and chances are one p

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ollen grain landing another flower is small ) which can carried for long distances and are easily inhaled , bringing it into contact with sensitive noses .
In the U.S. , people often mistakenly blame the conspicuous goldenrod flower for allergies . Because this plant is entomophilous ( with pollen spread by animals ) , the heavy , sticky pollen does not become independent of air . Most late summer and fall pollen allergies may be caused by ragweed , widespread anemophilous plant .
Arizona was once regarded as a haven for people with pollen allergies , although several ragweed species grow in the desert . However , as suburbs grew and people began building lawn and garden irrigation , more irritating species of ragweed gained a foothold and Arizona lost the claim of freedom from hay fever .
Anemophilous plants bloom in the spring such as oak , birch , hickory , pecan , and early summer grasses may also causing pollen allergy . Most cultivated plants with showy flowers are entomophilous and do not cause pollen allergies . In the U.S. , oak pollen starts to cause problems for people in February and disappeared at the end of April . [ 17 ]
The percentage of people in the United States are affected by fever varies between 10 % and 20 % , and allergies as it has proven to be the most frequent allergic response in the nation . There are certain evidential suggestions indicate hay fever and similar allergies be hereditary origin . Individuals who suffer from eczema or asthma tend to be more prone to develop long- term hay fever . [ 18 ]
The most efficient way to deal with pollen allergy is to avoid contact with the coarse powder . Individuals carrying the disease may at first believe that they have a simple cold summer , but it is more obvious fever does not go away when it looked cool . Confirmation of hay fever can be obtained after examination by a general practitioner . [ 19 ] Handling

SayaPoker.com Agen Judi Poker dan Domino Online Terpercaya Indonesia Antihistamines : Regular effective for dealing with mild cases of hay fever , this kind of non - prescribed medications , including loratadine , Benadryl and chlorphenamine . They do not prevent the release of histamine , but it has been proven that they are part of preventing a chain reaction activated by this biogenic amine , which is much lower fever . Side effects of antihistamines is somnolence , therefore , advisable to not take drugs while driving a car or for the consumption of alcoholic beverages . Although , reactions to these drugs on the side effects can vary from person to person . [ 20 ]
Decongestants : These medications are available in different presentations , such as a tablet or even a nasal spray . Decongestants such as Sudafed and drixoral can be obtained as an over-the - counter medications . Because oral decongestant drugs are known to raise blood pressure levels , it is recommended for people with hypertension to avoid them . Oral decongestant type can aggravate the symptoms of an enlarged prostate , making urination process is more complicated . [ 21 ]

Pollen in the human diet
Various manufacturers have started selling pollen for human consumption , often marketed as foods ( not supplements food ) . The largest constituent is carbohydrates , with protein content ranging from 7-35 percent depending on the plant species collected by bees . [ 22 ]
The U.S. Food and Drug Administration ( FDA ) has not found any harmful effects of pollen consumption , except from the usual allergies . However , the FDA does not allow pollen marketers in the United States to make health claims about their products , because there is no scientific basis for this ever proven . In addition , there is a danger that might not only from an allergic reaction , but also from contaminants such as pesticides and the growth of fungi and bacteria associated with poor storage procedures . A manufacturer states that collect pollen helps bee colonies is also controversial . [ 23 ] [edit ] Forensic Palynology Main article : Forensic Palynology
In forensic biology , pollen can tell a lot about where a person or object has been , because regions of the world , or even a specific location such
SituPoker.com JUDI POKER, AGEN POKER, AGEN JUDI POKER ONLINE INDONESIA BANK LOKAL as a particular set of bushes , will have a unique collection of pollen species . [ 24 ] Pollen evidence can also reveal certain seasons in which objects take pollen . [ 25 ] Pollen has been used to track activity in mass graves in Bosnia , [ 26 ] captures thief who sweeps the Hypericum bush during a crime , [ 27 ] and has even been proposed as an additive for

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