They're hair - like firs coming out of their upper ends. These taste buds are of four kinds telling us for main tastes-sweet ,bitter,sour and the front portion of the tongue is sensitve for sweet and salty tastes, the back portion is for the bitter and the edge of the tongue are for the sour taste. The central potion is not sensitive for any taste because it does not have taste buds.
The taste of food is known only when it is liqiud state. A portion of the food is dissolved in saliva which activites the taste buds. A chemical reaction produced by the food material generates nerve impusles reach the "Taste Centre" in the brain which ultimately gives the feeling of the taste. In addtion to the tongue, other senses also help in the preception of taste of food. The smell is also a part of the taste and felt by the nose. it is why one does not enjoy the total taste of food when one suffers from cold or influenza.
The Number of taste buds on the tongue of an adukt is more than on that of a child. The tongue of an adult has about 3000 taste buds. However, with the advancement in age, the taste buda start losing vitality and finally became almost inactive. The number of taste buds is reduced to just 400 in the case of a seventy years oldman. How does the tongue tell us the taste?
Due to constipation or indigation, some inpurties deposit on the tongue and they prevent the food particles from reaching the taste buds. Hence the taste of the food seems to be changed. Body fever and hot food also deativate the taste buds and thus the food doesnot give its real taste.
In the case if wine cocoa and fruit juices, it is the smell which helps in the realisation of the real taste. When these liquids are taken into the mouth, the tongue experiences the taste while their smell enters the nose and through the "Smell nerves" It reaches the brain. In this way the total pleasure of the taste is derived.
How Does the owl see at Night?
There are all kinds of birds in the world and owl is one of them. What is peculiar about this bird is that it can see more clearly in the night than in the day. Its ears are also very sensitive. At night if there is a slightest movement from any of its pery, it can detect and catch it very easily.
It's leg have four claws with curved nails which specially faciliate it to seize its prey. Mice are its favourite food.
Owls are found almost in evry part of the world. In some countries they are treated as inauspicious birds, while in some others they are regared as symbols of wealth and wishdom. It is a bird that really comes to life at night and its whole body is especially suitred to nocturnal activity. The Birds having clearer vision in the night are called nocturnal birds. On the other hand the birds which can see clearly in day time are called diurnal.
You must be very curious to know how this bird can see so clearly at night.
To understand this it is essiential to know how we see the things. Light Scattered by every object is focused on to the screen of the eyes by the lense inside the eyes. This screen of of the eyes is called the retina. An inverted image of the object is formed on the retina which is carried to the brain by opetic nerve.
This is erected by the brain and the wee see the object. The owl's eyes have four special feaures, due to which it can see more clearly in the night.
Firstly the didtance between the lense of it's eye and the ratina is more than the distance in the case of our eyes. Due to this the image formed on the ritena is bigger in Size. A special organ of it's eyes named "pecten" assists in focusing the lens in adjusting it for various distance. Secondly the number of "rods" and "cones" in the retina is very large almost 10,000 per sq mm compared to 2000 sq mm in our eyes. Thus the owl can see five time more than us.How Does the owl see at Night?
Thirdly it's eyes have a red coloured material chemically a protien which makes its eyes more sensitive to light. fourtly the pupils of it's eyes can dilate more thus allowing even the smallest among of light to enter the eyes. Due to these four factors , the owl can see more clearly in the night.
Do ants also have their Kingdoms?
Do you know that the ants have their own world? they also have cities and live in groups like us. They also have kings and queens and servant ants for doing various jobs. They have armies which are capable of facing the biggest of the big animals.
More than twothousand kinds of ants havebeen studied so far. The biggest ant is found in africa. It is three inches in length. Ants live in groups. Their groups are both large and small. These groups are found everywhere.
Every class of ants has a separate army which attacks the ants of other classes. Strong ants drive out the weak ants from their holes and caputure them. They even capture their eggs and when ants come out from these eggs, they use them as their selves. Millions and Millions of ants of one category live like one country. They have kings and queen takes various types of works from slave ants. The slave ants are engaged in service for their whole life time. the male and female ants contract marriage also.
The farmer ant manages food for other ants. Some classes of ants are very cruel. There is class of ants found in central africa, south america and south asia, which is non-vegetrain. These ants come out in groups of millions in search of their prey and if some animal falls in their trap, they eat away all the flesh of that animal.
"The Ghosts and Evil Spirits a reality?"
Every race or religion has some degree of faith in the existence of ghosts and evil spirits. Quite frequently, Newspapers publish stories throwing light on the existence of ghosts and evil spirits. Some people claim to have even seen them.
According to the hindu religion they are a separate species. After death, man may become a ghost or evil spirit depending upon the quality of his deeds in this world. They have no specific from, but they can assume any form. They are not visible to the eyes. They can become visible or invisible anywhere. It's belived That generally they lives in the ruins of bildings, burial places ponds, deserted wells, Solitary places and on peepal, baayan trees etc.
In many races some rituals are performed after the death of a man or woman with a view to ensure that the ghost of dead does not harass the living ones. But scientists have different view in this matter. They treat their existence as a figment of imagination. According to scientfic facts, this is either an illusion or hallucination of the mind and eyes. In illusion, something does exist, but our mind and eyes take it to be something elase.
Mirage in a desert is an example of illusion. the thirsty deer sees water pools some distance away infront of it tries to reach the water to quench it it's thirst. But the water seems to recede further away.. The deers continue it's efforts to reach the water, but it never reaches there. This way the deer gets lost and dies. This illusion of water in the desert is caused by total internal refelection of light. As a matter of fact, water does not exist there, but due to the total internal refelection of light,the inverted images of trees and plants give an impression of water. In hallucination, nothing exists in reality. This is caused by some anxiety or tension in the mind.
Some intoxicating medicines also cause hallucination.The Ghosts and Evil Spirits a reality? In hallucination, man hears different voices, sees peculiar creatures and sometimes he sees frightening, gigantic faces whom he considers to be ghosts. Under the influence of cocaine, one feels as if some insects are crawling on the skin.
Scientists have, therfore, concluded that ghosts are an illusion or hallucination of the mind. They don't have a real existence.
"Why does ice float on water?"
It is a matter of common experience that ice floats on water. Howsovever large the size of ice maybe, it will not sink. Even ice bergs keep on floating in the sea. Do you know why ice floats on water?
The law of floation of bodies was given by the Greeck Scientist Arcchimedes. According to this law, when ever a body is placed in water, it is accept by two forces the weight of the body acting downwardes and the buoyant force of water acting up wards.
If the weigh of the body is equal to or less than the weight of the water displaced by it, it will float
on water. On the other hand, if the wight of the body is more than weight of the water displaced.
A piece of wood floats when its weight is equal volum of water, that is why half of wood is under water, While theother half is above water. Similary, the weigh of coek is one fifth of the weight of the water displaced by it, so one fifth of cork is under water while the rest is above water.
You can understand the floatation of ice also on the basis of this law.
In general when a liquid changes to solid, it contracts because its molecules comes closer to each other in the solid state. As a result of this the volume of the substance decrease or its density increases Hence a substance becomes heavier in solid state, than in the liquid state.
But water is a peculiar liquid. When it becomes ice, instead of contracting, it expands. The volume of ice becomes more than that of the water. Ice is about nine-tenth as heavy as water. This means that we get about 10 liters of ice made out of 9 liters of water. Ad you know , "Liter" is a measure volume, not of wight, The effect of the increase in the volume of ice is that it's density becomes nine-tenth of that water that is ice becomes lighter than water. It is why nine-tenth of ice is submerged in water, while only one-tenth is above water. The ice under water (9/10 of the whole)
Displaces water whose weight equals that of the whole ice. This law of floatAion is derived from Archimedes principle. This also explains how the maxmium portion of the gaint icebergs remains sunmerged in water while only a tip (1/10 part) is above water. This has been clearly shown in the digram above.Why does ice float on water?
Bursting of water pipes in cold regions is due to the volume of ice being greater than that of water.
As soon as water freezes to ice, the volume is increased which produces strong force by which pipes burst. In Finland, the property is utlised in breaking rocks. Water is filled in empty spaces aviable between rocks. When water freezes, it expands and generates enough pressure to cause cracks in the rocks.
"What is regeneration?"
Would it not be wonderful if people who lost an arm or a leg or even finger in an accident could simply grow another one in its place? But in reality it does not happen in case of human beings. However, You will be surprised to know that there are some living beings in which a new limb develops at the point from where the original limb has been lost. development of a new part in place of a lost part is known as regeneration.
Some creatures have the unique ability to regenerate their body parts. If small arm of a starfish is cut off or destoyed, it is regenerated. The hydra is also endowed with this wonderful capability of regeneration.
The ablity of regeneration is different in different creatures. Living begins with complicated structures have lesser ability of regeneration. Man and other mammals have complex constitution.
That's why they have lesser ability of regeneration. Because of lesser ability of regeneration. Once our legs or hands are cut, they are not regenerated. Though in ourbody also, some type of regeneration takes place.
For Example, if the skin in any part of the body is burnt or cut, new skin comes up ther again. Regrowing of wings of birds is another example of regeneration,What is regeneration?
In some species new tissues grow from the surface of the wound and replace lost or damaged tissues. Somtimes, the tissues that an organism regenerates, are different form orginal tissues.
The regenerated structure maybe smaller than the orginal.
"How Does a Prism Produce rainbow Colours?"
The Sun light Which seems to be white is composed of seven colours. Issac Newton, Father of Physics, proved it for the first time in 1666. He demonstrated with the help of a glass prism that sunlight comprises violet, indigo, blue, green, yellow, orange, and red (VUBGYOR) colors.
The question arises: What is a prism and howdoes it seperate the seven colors of white light?
Prism is made of transparent glass with three faces. Two of them are triangular and remaining one is rectangular,each edge making an angle of 60. If we see an object through a prism, it will look multi-colored. Whenever a ray of light passes through a prism, it deviates from its path and bends towards the base of the prism.
This property of bending of light from its path while passing from one medium to another medium is called "Refraction" of light. As already said, white light is composed of seven colors. While coming out of the prism, these different colours deviate at different angles. These colors consitute what we call the spectrum. The red colour deviates least from its path whereas violet colour deviates maxmium. How Does a Prism Produce rainbow Colours?That is why the red colour occupies the uppermost part of the spectrum,
While voilet the lowermmost. Other colours are in between these two. Separation of white light into seven different colours is called the dispersion of light. These are the same seven colors seen in rainbow. This is how a prism disperses white light into the seven rainbow colours.
"Are the Molecules of all substances in motion?"
Every substance is made up of very tiny particles called molecules. A molecule is the smallest part of the matter that can exit independently and exhibits all the properties of that matter. For example
if we take a molecule of sugar, it will exhibit all the properties of sugar such as taste, shape, color etc. Mlecules of different substances differ in size.
Some are only few billionths of a centimeter in size while sorne other molecules are thousands of times lager. Molecules of gases are small in size. One cubic centimeter of air contains about
25,000,000,000,000,000,000 molecules.
Even though a tiny piece of matter contains a very large number of molecules, yet there are empty spaces in between them. Molecules of matter are constantly in random motion. As the temperature increases,the motion of the molecules also increases. The hotter the substance,the faster is the motion of the molecules. Molecules of a gas move very fast in comparision to the molecules of liquids and solids. Even the molecules of ice are in motion.
Now the question arises:when molecules of all the substances are in motion,why don't substances appear shaky? The reason is: There exists a force of attraction between the molecules which keeps them together.Are the Molecules of all substances in motion? If this force is not persent, the molecules of matter will scatter away in all directions.
When heat is given to the molecules of a solid, the speed of the molecules increases and the force of attraction decreases. If we continue adding heat, the spped of the molecules would be still faster and the solid will change into liquid and finally to gaseous state.
"WHy Does the Sun appear red while rising and setting?"
When the sun rises in the morning , it appear like a red ball. As the day advances, the colour appears white, but at the time of sunset in the evening, the colour again evening, the colour again
appares red. Do you know why it is so?
We know that the earth revolves round the sun. The part of the earth reciving the sunlight is lighted
and we say it is day in that part. We also knowthat the white sunlight comprises seven colours- voilet, indigo, blue, green, yellow, orange and red. In the morning and eveningwhen the sun is near the horizon,
The rays have to travel a longer path in the atmosphere to reach to us than in the noon. The distance travelled by the sun rays in the atmosphere in the morning and the evening is fifty times more than that in the noon. The dust, smoke and water vapours present in the atmosphere scatter away these colours differently. Voilet is scattered most and red is scattered least.
Therefore, the amount of red light which reaches our eyes in maximum. As a result the sun appears red white rising and setting.
"What is QuickSand?"
Quicksand is a peculiar creation of nature. Though it has an ordinary apperance, yet it is very dangerous. From a distance, you cann't distinguish between ordinary soil and quicksand. By mistake, however, if some body enters quicksand, he will slowly go down and finally sink in it.
Once you are trapped in quicksand, it is very difficult to get out of it.
Quicksand can devour anything big or small. Do you know what quicksand is, how it is formed and how to save oneself if trapped in it?
Broadly speaking, quicksand is a type of slush, but its depth is much more. Quicksands are normally formed on such riverbanks and sea shores where the earth's crust contains layers of clay with huge quantities of sand above. Water waves deposit water into this mixture of clay and sand.
The inner layers of the clay prevent the water form drainning away.
Slowly and slowly this stagnated water starts rotting and converts the entire siol into deep slush. It becomes pasty.It is how quicksand is formed.
Quicksand contains more of water than soil. Hence people can swim in it. But it is dangerous to swiftly move hands and legs the moment you are trapped in it. On the contrary you should make slow movements and allow water to accumlate around you.
You will find it easier to swim in this accumulated water and coninue alive to the solid ground on the bank. This way you can save yourself from quickand.
Why was the Great Wall of china Built?
The construction of this great wall was started in the year 221Bc. and it took almost 15 years to complete this work. This was buit of stones and bricks. Now the questions arises what was the necessity of constructing such a huge wall?
This great wall was built to protect China from Mongol invaders. About the Year 246Bc. china was divided amongst small provinces.
King Shih Hunag li united different provences of chanina into an empire.
To the north of this empire. To protect china from this danger he ordered the construction of a huge wall. So a wall starting from Shanhi kuan in the bay of pohai to Chiakuman in Kansu was constructed.
Did the king archive his goal? Unfortunately---no, because the wall was broken at many places and mongols got an opportunity to attack china. the purpose of constructing the wall could never be fulfilled.Still many parts of the wall are broken. Now the chinese have even taken to farming beyond the wall.
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