Body Boarder Eats Sand!

What is morse code?

      Morse code was invented by Morse Samuel Finley Breese, an American artist and inventor. It was in the year 1832 that he got the idea of sending messages through telegraph. He worked hard on it and in 1838, he got success. As the telegraph lines were not in existence at that time, it was not put to immediate use. It was in the year 1843 that the US government sanctioned a sum of money to lay telegraphic lines.

      The first telegraph line was laid between Washington and Baltimore. In 1844, Morse sent his first coded message. The code consists of signals sent in the form of dots and dashes. It is used in sending telegraphic messages. The dotes and dashes stand for letters and numerals. The dot is a short signal, while dash is a long one. The duration of three dots. The coded messages are sent through a transmitter. These are carried through radio waves along a wire. At the receiver’s end, the message is received in dots and dashes. It is then decoded.


Fact
      Morse code proved to be very useful during the First World War. It was the quickest and easiest way of sending and receiving messages. SOS was the most used signal. It stands for ‘Save our Soul’.

Amphibians

      Amphibians evolved from fish like animals. They spend most of their lives on land and go to breed in water. There are nearly 4,000 species of amphibians. Out of eleven major groups found only three groups have survived. These are frogs, toads, newts, salamanders and caecilians. All amphibians lay eggs. Amphibians are classified into three groups Apoda having no legs like caecilians, another group Urodela consists of newts and Salamanders and Anura which consists of toads and frogs. Amphibians breathe through their lungs. Since their skin is not scaly it keeps them always moist.


Frogs and toads – Frogs and toads are very common amphibians. There are nearly 3,400 species of frogs and toads and all of them look almost similar. They spend their early life in water and later move to lands and back to water for breeding. Frogs do not have a tail. They are found everywhere except in Arctic or Antarctic regions.
The skin of these amphibians must remain moist as they have poorly developed lungs. The moist skin of amphibians help them to breathe by absorbing more oxygen. If they dry out they run out of oxygen and eventually die. A frogs lays its eggs in the water. When these eggs hatch, tadpoles which look like fish emerge. These tadpoles have a tail and they breath through the gills as they have no limbs. Their development depends on the temperature of the water.
      They develop large gills to get enough oxygen from the water. It is through metamorphosis (stage of development) that it changes into a frogs. Gradually tail disappears and legs are formed and it starts to hop.
Frogs and toads are of the same family. The skin of the frog is smoother than a toad. Toads have shorter legs than frogs.
Both of them eat insects and have long sticky tongues with which they trap their prey.
Toad

Golden arrow poison frog – Golden arrow poison frogs have poison in their skin and one frog can kill nearly 1,500 people.
The bright color of this frog warns its predators. They are found in the tropical forests of Central and South America. The more brighter the frog the more horrible flesh it has.

Stages of development of a frog:
1. The fertilized egg, known as spawn is contained in a bag of jelly.
2. Young frogs known as tadpoles are formed.
3. Tadpole after 7 weeks begins to grow their hind limbs and fore limbs. These tadpoles breathe through their lungs.
4. After 14 weeks a tadpoles gets matured and develops into a frog. It soon leaves the water.

Newts and Salamanders – Newts and Salamanders are other common creatures. There are nearly 250 species of newts and salamanders. They love to stay in cool dark places during day time and become active only at night.
They eat insects, snails and worms. Both newts and salamanders have a cylindrical body with four legs and a long tail.
Salamanders look like lizards with no claws and no scales. They are large than newts. They can easily grow a tail if they lose one. While newts are mainly aquatic with webbed feet.
Newt

Spotted Salamanders – Spotted Salamanders are rarely found. They spend most of their time burrowing in the damp soil. In spring they accumulate in large numbers to breed together.
Salamander

Pacific Giant – Pacific Giant are the largest of all the Salamanders found in North Western America. They remain silent and make low pitched sounds.
They eat snails, slugs, insects and small minute creatures. A female Salamander lays about 100 eggs on a branch during spring season.

Warty newt – Warty newts develop gaged crest on their back during breeding season and females are large than males. They eat mainly fish and small amphibians and even their eggs.

Eastern newt – A female Eastern newt lays nearly 400 eggs on the water plants. After sometime the larvae turn into semi adults known as efts. The newts breed during spring season.

Caecilian – Caecilian are blind amphibians with no legs. They resemble worms and have teeth with jaws. They live in swamps and streams in the tropical region of the world. They form the smallest group of amphibians.

Saturn

       Saturn is the sixth planet from the Sun and the second largest in the solar system. Saturn looks flattened when viewed through a small telescope. It’s equatorial and polar diameter vary by almost 10%.

How is Saturn’s atmosphere?
       The atmosphere of Saturn, like that of Jupiter, is only a narrow region, compared to the vast interior of Saturn. The three cloud decks are found mostly low in atmosphere, while hazes of smog are found higher up.

Have many satellites does Saturn have?
       Saturn has 18 named satellites plus 12 recently discovered and as yet unnamed ones.

What about Saturn’s moons?
       The gas giant planet Saturn has a large group of 31 moons. Saturn’s moon Titan is one of the few moons in the solar system with much of an atmosphere. It is also one of the largest moons in the solar system.

Describe the composition of Saturn.
       Saturn is about 75% hydrogen and 25% helium with traces of water, methane, ammonia and rock, similar to the composition of the Primordial Solar Nebula from which the solar system was formed.

How does the Saturn’s interior look like?
       Saturn’s interior is similar to that of Jupiter’s, consisting of a rocky core, a liquid metallic hydrogen layer. Tracks of various ices are also present. Saturn radiates more energy into space than it receives from the Sun.

Give a brief description of Saturn’s rings?
       Saturn’s rings, unlike the rings of other planets, are very bright. Though they look continuous from the earth, the rings are actually composed of innumerable small particles, each in an independent orbit. They range in size from a unit meter to several meters.

Blow The Skirt Prank In UK

Lichens and Algae

1. Lichens
      Lichens are unusual creations as they are not a single organism but a combination of algae and fungus. They live together, the algae is enclosed inside a fungus. Since algae has chlorophyll, with the help of sunlight it is able to make its food which is used even by fungus. The fungus provides anchorage to algae so that it easily absorbs the nutrients and water. Lichens mostly live on rocks, walls and trunks of the tree. This partnership of fungus and algae is known as symbiosis.

2. Algae.
      Algae are a diverse group of primary aquatic plant like organisms which were previously classified as a primitive subkingdom of the plant kingdom called the ‘thallophytes’. But at present they have been classified into another major group known as ‘eukarya’ which includes animals and the higher plants. Algae have chlorophyll and can manufacture their own food through photosynthesis. They are found in polluted water, in seas, rivers and lakes, on soils and walls, in animals and plants; in fact everywhere. The simplest algae are single cells. The more complex one consists of many cells grouped in a colony which is spherical in shape, e.g. Volvox.
      Seaweeds are algae that are found in the sea or brackish water. Seaweeds are of three basic colors – red, brown and green. Most seaweeds remain submerged under the sea but during the low tides they are exposed to the sun. Seaweeds use the energy of sun to carry on the process of photosynthesis which helps them to oxygenate the water.
      Algae are usually fish food, and they also supply oxygen to water through photosynthesis.
Seaweeds

Aztec Civilization 4

1. What was the importance of Cholula?
       Cholula was the Holy Place of the three major satellite cities of Teotihuacan. It was destroyed by Cortes and his men on their way to take over Tenochtilan. The pyramid is in the present day city of Cholula and, in volume, (before destruction) was larger than the Egyptian pyramid of Cheops. After conquest, a church was built on the top of the ruins.
       Three successively larger pyramids were built on top of each other here, and served important ceremorilal purposes for the Aztecs. The last and largest pyramid was laced with stucco, which, if not maintained, turns back to mud.
       When the pyramid was abandoned, the stucco turned back to mud, and plants and eventually trees grew on it.
       Historians think that the Spaniards were not aware that they were building their church on top of an Aztec pyramid – perhaps they just built it there because it was the highest hill in the area! However, it is very common, both in Mexico and in other cultures with conflicting belief systems, to see buildings associated with one culture constructed on top of or from the rubbles of buildings associated with the other culture.
       In Izamal, for example, a large cathedral and courtyard are built on top of a lopped-off pyramid. In India, too, one can see mosques constructed from stones whose carvings show that they were originally part of Hindu temples.
Tula

2. Describe briefly the pyramids of Teotihuacan.
       In Nahuatl, Teotihuacan means ‘The City of the Gods’, or ‘Where Men become Gods’.
       The plazas, avenues, and great pyramids of the city of Teotihuacan were laid out as a symbolic sacred landscape of artificial foothills and mountains.
       The complex of approximately 600 pyramids of various sizes is dominated by the great Pyramid of the Sun which, it was discovered in 1971, was built over a natural cave with four chambers. Mesoamerican belief saw caves as gateways to the spiritual world (called Xibalba by the Maya). The cave contained remains of offerings and may have been a center for shamanistic rituals from a much earlier period. Threr can be no doubt that the Pyramid of the Sun was deliberately built over the sacred Cave.
Pyramids of Teotihuacan

Windstorms

       The wind generally does not flow in straight line, but it swirls into spirals. When these wind spirals grow into terrifying storms, they take the shape of hurricanes and tornadoes, which have the fastest wind speed on the Earth.

1. What is wind’s effect and why it happens?
       When the air, instead of moving straight in to the cyclone, circles around it in a spiral, this is called the wind’s effect. It happens because the spinning of the Earth always pushes winds to one side.

2. How are the winds caused?
       Winds are caused when the high pressure air rushes towards the low pressure areas, which are called cyclones.

3. Briefly describe Hurricanes.
       Hurricanes are powerful windstorms. They are very huge and can be hundred of miles wide. They form only in very warm, wet conditions, generally over the sea in tropical areas near the equator.

4. How do tornadoes form?
       Tornadoes form during violent thunderstorms, when a hot fast moving, upward air current meets a cold, downward air current. Tornadoes are much smaller then hurricanes, but they can by much more violent and dangerous. The wind inside the tornado’s funnel can be as fast as 480 km/hr.

5. How long can the tornadoes last?
       The tornadoes are soon over. They can last for five minutes, while the hurricanes can last for 10 days. The tornadoes grow weaker and fade away as the air inside grows colder and the pressure comes out.

6. What id Tornado Alley?
       There are places, which have frequent thunderstorms and lots of tornadoes. Such places are called Tornado Alley. Part of the USA, between Texas and Illinois is known as Tornado Alley.

7. What are water spouts?
       Sometimes, a tornado forms over the sea. It sucks the water up into a towering spout, reaching up to the clouds above. These tornadoes are called water spouts. Sailors used to think that they were long snake like sea monsters.

8. What kind of devastation Hurricanes do?
       Then Hurricanes hit the ground, they cause massive damage. Winds blow at a speed of 240 km/hr. They destroy buildings and rip the trees out of the ground. The hurricanes die soon after hitting the ground, as there is not enough moisture to support them.

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What is Our Skin for?

       Skin covers all our body except for the eyes. It provides a barrier against organisms and protects us from minor injuries. It is water-proof. The skin helps to maintain our body temperature.
       When we fell hot, the skin changes color because tiny capillary blood vessels in the skin expand and heat is lost from the blood.
      It also helps to retain body heat during cold conditions by narrowing the blood vessels in the skin.
Skin layers

      The skin being water-proof, prevents moisture from escaping. Although we sweat during summers, this is useful as it cools down the body. The skin contains many nerve endings and receptors, which give us sense of cold, heat, touch and pain.

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Amazing Swimming Babies

       Clip

When were the first matches made?

       Perhaps, the first matches were made by the cave man. He learnt to make fire with the spark created by rubbing two pieces of stones together over a pile of dry leaves. Later on, he used a fire drill. Fire drill was a wooden stick. It was struck over a piece of dry wood. It produced heat to make fire.

       In the modern times, phosphorous is used to make matches. Phosphorous is a material that catches fire easily at a low temperature. It was first used, to make fire in the 19th century. To begin with, pieces of sticks were coated with white and yellow phosphorous. However, these matches proved to be dangerous as white and yellow phosphorous catches fire very quickly. In 1844, red phosphorous was used to make matches. Red phosphorous was tinted on the two striking sides of the match box. The heads of the match sticks were coated with antimony trisulfied and oxidizing agent. When struck, the heat of friction changes the red phosphorous to white phosphorous and ignites it.

Fact
       The brimstone match was among the first matches. To make such a match, thin strips of wood were dipped into melted sulfur; the sulfur points ignited when applied to a spark produced by a flint.

Reptiles

       Reptiles evolved from amphibians nearly 300 million years ago. Nearly 225 million years ado reptiles dominated our earth and lived for more than 150 million years. There are more than 6,560 species of Reptiles known to man.
       These include alligators, snakes, turtles and crocodiles. Reptiles are cold blooded animals and can change their body temperature with the temperature of their surroundings.
During winter they go for a winter sleep known as hibernation. Reptiles live on land except for some reptiles like snakes and turtles which live in water. Alligators and crocodiles live both on land water.
       Since they have evolved a dry and scaly skin which is waterproof, the water inside their body doesn’t dry, thus, enabling them to remain outside water.
       They can be seen all around the world except at the poles. The eggs laid by reptiles have a leathery shell which, prevents the contents from coming out. The yolk provides food for the embryos.
       Since prehistoric times, only four types of retiles have survived till now, these are 1. lizards, 2. turtles and tortoise, 3. crocodiles and alligators and 4. snakes, apart from these another group is the New Zealand Tuatara.

Snakes – There are nearly 2,500 species of snakes found on the earth, out of which 800 are poisonous and nearly 250 are dangerous for human beings. The snakes found in the sea are dangerous than those found on land.
       King cobra is one of the most poisonous snakes. Another poisonous snake is the African black mamba which can travel at seven miles per hour and is twice as fast as people can walk. The rattle snake is yet another poisonous snake.

       Snakes have no ears. They can only feel the vibrations. They have long bodies with no limbs but still are able to move fast. The scales present on their body help them to grip the ground. Snakes generally kill prey much larger than them.
       Their jaws are extremely flexible and this enables them to push their prey down through the throat.

Crocodiles and Alligators – Due to their differently shaped heads Crocodiles and Alligators look different from each other. Alligators have a short blunt nose while crocodiles have a longer and thin nose known as snout.

       Both crocodiles and alligators are meat eating animals. At a younger age they eat small animals like fish but when they grow up they can eat big animals like deer, antelope etc. Inspite of being fiercely predators, they are gentle parents.
       They build nests for their eggs and stay by them till they are hatched. The mother alligators protect the new born from other animals.
       Apart from this mother alligators even help and carry them to water.
       Crocodiles are believed to be excellent swimmers and their length varies from 1 meter to 7 meters. The estuarine crocodile is the biggest of all the crocodiles found in the Indian Ocean and is about 7 meters long.

Lizards – Lizards are cold blooded animals with dry scaly and water tight skins. There are nearly 3,700 species of lizards and it forms the largest group of reptiles. Lizards have four limbs and are active climbers and runners.

       Whenever a lizard gets trapped by its tail, it can easily leave its tail behind and run freely. Whenever lizard loses its tail grows a new tail after a few weeks. The new tail is smaller than the previous one. Some of the lizards are Skinks, Tuatara, the Frilled lizard, Chameleon, Marine iguana, common iguana etc.

Skinks – Skinks are found in Africa, East Indies and Australia. There are nearly 600 species of Skinks. They have thin and small legs.
       The head of a Skink is small and pointed and it can easily crawl over the rough and uneven surface. Skinks can easily see with their closed eyes. They have a transparent eye lid over their eyes.

       With the help of which they can close their eyes and still look. One of the interesting characteristics of a Skink is that it can easily squeeze its size during the squirming movement in the soil. Some Skinks’ feet are very small as compared to the size of their body. They live on or under ground and are either herbivorous or insectivorous.

Tuatara – Tuatara is also known as Sphenodon punctatus. It is a strange lizard with three eyes. It is the only reptile which is placed in a separate sub group-rhynchocephalia. It is found in New Zealand.
       It originated nearly 200 million years ago on the earth. Tuatara remains active during the hight and lives in burrows.
It eats frogs, rats and eggs of birds.
       The average life of Tuatara is up to 77 years but some live up to 100 years. This animal is on the verge of extinction. Its third eye is located in a hole between head and brain.

European green lizard – European green lizard are one of the most beautiful of reptiles. They are found throughout Europe. They are sold at pet shops and need extra care. They eat insects, spiders and worms.

Frilled lizard – Frilled lizard are found in New Guinea and Australia. They have unusual fold around their neck. Whenever they are threatened they spread their skin, which looks three times as large and makes them look very dangerous and keeps the predators away.

Turtles, Tortoises and Terrapins – There are nearly species of Turtles, Tortoises and Terrapins. All of them have hard shells on their back. The shell is made up of bones which protect their soft and delicate bodies. The head, leg and tail project out of their body.

Giant tortoise – Giant tortoise are found only on the isolated islands and weigh up to pounds. Tortoises are land turtles and they can live up to years. There are two species of giant tortoise, one lives in Seychelles and Aldabra islands while the other in Galapagos and they weigh more than 230 kg.

River Terrapins – River Terrapins are plant eaters, and are generally found in rivers and in saltwater.
They are normally seen on the sandbanks. Efforts are being taken to protect them as they are at the verge of extinction.

Evolution of animals

       We know about living things on the earth from the fossils, which are the remains of dead plants and animals that turned into stones, gradually, over millions of years. From the remains we come to know that the oldest era, the Paleozoic era contained fossils ranging from many primitive life forms upto some of the earliest land dwelling animals. During this era fishes, amphibians and early reptiles appeared.
Fossils

       The Mesozoic era was the age of giant reptiles when dinosaurs stalked the world. The Cenozoic era in which we live is the age of mammals and birds. All fossils can be placed in this era.
       Life initially evolved in the sea. The earliest creatures were minute and simple in their structure and were capable of reproducing. These living organisms were neither plants nor animals as their life in the animal and plant kingdom at present.
       The first microscopic life forms were like little balls of jellys known as flagellate, which with the help of sun’s energy fed itself and grew. Flagellates were so tiny that they left no trace of their existence. It took many years for the flagellates to develop into half plant and half animal, then separately into plants and animal cells. By Paleozoic Era animals like Jellyfish, Starfish, Sponges, Nautiloids also started appearing in the waters.
       The earliest and simplest multicellular organisms were jellyfish, corals, sea anemones and hydroids. Their body had two layers ectoderm and endoderm with groups of cells known as tissues which were specialized for digestion, movement, reproduction and coordination. Next advancement was the three layered body such as platyhelminthes, flatworms and tape worms etc.
       Gradually animal bodies became larger. Thus a proper circulation system was needed for the distribution of nutrients and removal of waste products from its body. Animals like annelid worms had hard mouth parts which they used for cutting food and earthworms fed itself by extracting nutrients from the soil.
       The earthworm is divided into segments, each having blood vessels, nerve ganglia, muscles and an excretory system. Mollusk and echinoderms had effective circulatory system needed for the transportation of oxygen and nutrients in the body. Most Mollusks are provided with gills which absorbs oxygen from water and releases carbon dioxide into water. The blood vessels running through gills bring in the oxygen.
       Starfish, sea cucumbers, sea urchins fall under the category of echinoderm. A starfish turns its stomach inside out through the mouth to envelope the prey and digests the soft parts and sucks in the materials which can easily be digested.
Mollusk

       The circulatory system appeared since the time of evolution even in the earliest living cells, while powerful circulatory systems appeared in bigger animals. Life was gradually being created and more complex orders of animals developed.
       During the beginning of Palaeozoic Era armored animals like crab and lobsters, trilobites developed. Later giant sea snails like nautiluses with long tentacles developed. It could crawl at the bottom of the sea and snatch its prey with its long tentacles. Then came the vertebrates.
       These animals had a backbone and the higher order of animals started coming. The first vertebrates appeared in the sea like, Ainiktozoon. These were jawless and could only swallow tiny creatures. Fossils give evidence that the first fish appeared in the Ordovician period nearly 460,000,000 years ago. These were the most primitive jawless fish. Their mouths had a simple opening through which it fed on its food. Then came the fish with jaws, these were called placoderm.
The jaws evolved from gill arches which formed the body support of the gills. Then evolved the present day fish, and later appeared new forms of fish with jaws and teeth. These animals were tiny but some of them were giant like Dinichthys which were 6 metres in length. Fishes could breathe through the lungs and gills. Now we will discuss the appearance of animals on land.
       Around 400 million years ago our planet Earth was covered with greenery which provided food and shelter to the land animals. The first land animals were spiders, cockroaches, millipedes, centipedes etc. Cockroaches were first to fly and soon others learnt to fly. It is interesting to know how the fish became amphibians? When the continents were raised many rivers and lakes dried up and most of the fish died while some survived and they dragged themselves with the help of their fins. Some stayed in wet lands while some moved to dry lands.
       This is how the first amphibious animals came into being. These amphibians never moved far off from water as they didn’t know to make hard shelled eggs which could be left on the ground.
Later they learn to make hard shelled eggs. Dinosaurs, the gigantic reptiles, evolved form these amphibians during the Mesozoic era. Scientists have gathered information from their fossilized skeletons.
       Their weight can be calculated by studying their bones. According to scientists these animals had very strong muscles and large digestive system based on the type of food they ate. They survived for about 150 million years. The first reptile was Seymuoria a small animal. These reptiles quickly started multiplying themselves.
It was during this period that tortoise and other small reptiles evolved. Cynognathus was the first animal to have warm blood in its veins. During Mesozoic Era Saltoposuchus, a small reptile also evolved.
       It had learnt to stand and walk on its muscular hind legs; it even used its clawed fingers to grab its prey. After dinosaurs birds and crocodiles also evolved. Various reptiles appeared and developed the ability to glide but only pterosaur could develop true flight.
       They had short arms and their wings were supported by an enormous long fourth finger while the other fingers moved freely. Their body was extremely light having hollow bones and they were efficient flyers. They did not have feathers and their large wings were more like a bat with fur on their body which made them warm blooded. Archaeopteryx, which lived during the days of dinosaurs, was as big as a pigeon but it was a mixture of both bird and reptile. It had movable claws, fingers on its wings, with twenty individual joints on its tail. It had a toothed jaw, and its body was covered with feathers. Later on giant birds appeared with savage beaks.
       They were incapable of flying but could run at an alarming speed. Nearly 70 million years ago, a great giant bird named Onactornis lived. Its height was 3 metres with a 40 centimetre long beak. Its prey included large mammals. It tore their stomach, killed them and fed on them. Then came the mammals, they appeared during the age of dinosaurs. The true mammals appeared during the Trisassic period. These mammals were small and once the dinosaurs died out the mammals grew gigantic. They were more intelligent than dinosaurs.
Dinosaur

       These animals were warm blooded and had a maternal instinct which made them to look after their babies until they were ready to stand on their own feet. These animals were known as mammals as they had mammae or milk glands by which they fed their young ones.
Archaeopteryx

       Mammals developed from small rodents to herbivores and carnivores. Some of the ancient mammals were prodiacon, a primitive hedgehog, Taeniolabsi etc. While some of the giant mammals, Baluchitehrium, were a huge rhinoceros of Oligocene period. Even human begins belong to a group of mammals known as primates. Early man was like an ape with long arms and walked upright.
       They were replaced by Homo erectus which had heavier jaws, bony ridges and a sloping forehead. Later on, these Homo erectus developed into Homo sapiens, the present day man.

Interesting facts
        It was thought earlier that dinosaurs laid their eggs in isolation. But in 1978 a remarkable find was made in Montana, U.S.A. Fifteen Maisaurus babies were found scattered around a large mound shaped structure, together with broken egg shells. The nest was about 2 meters across and covered with vegetation.

Jupiter

       Jupiter is the fifth planet from the Sun and, by far, the largest. Jupiter is more than twice as massive as all the other planets combined. Jupiter is the fourth brightest object in the sky.


       Jupiter has a huge magnetic field, much stronger than Earth’s. Its magnetosphere extends for more than 650 million kilo meters. Jupiter’s moons, therefore, lie within its magnetosphere.

       Jupiter and other gas planets have high velocity winds, Which are confined in wide Bands of latitude. The winds blow in opposite directions in adjacent Bands.

       Jupiter has 39 known Satellites, the four large Galilean moons, 23 smaller named ones, plus 12 more small ones discovered recently, but not yet named.
       Interior of jupiter


       Jupiter is about 90% hydrogen and 10% helium and tracks of methane, water, ammonia and rock. This is very close to the composition of Primordial Solar Nebula from which the entire Solar system was formed.

       Galileo discovered Jupiter’s four large moons in 1610. The four large moons of Jupiter are IO, Europa, Ganymede and Callisto.

       Jupiter was first visited by Pioneer 10 in 1973 and later by pioneer 11, Voyager 1, Voyager 2 and Ulysses. The spacecraft Galileo is currently in orbit around Jupiter.
       Pioneer 10


       Jupiter has rings like Saturn’s, but much fainter and smaller ones. They are probably rocky material. They were totally unexpected and were only discovered when two of the Voyager 1 scientists insisted that after traveling one billion km, it was, at least, worth to see if there are any rings.

Bacteria

       Bacteria are minute organisms and the lowest members of the plant kingdom. They are nearly 0.0001 millimeters in diameter. Some of them are so small that they cannot be seen without the help of a microscope. Bacteria has no membrane with an en closed nucleus mitochondria or chloroplasts. It has a single chromosome. Bacteria is usually found in one of the three shapes
Coci – the ball shaped
Bacilli – the rod shaped
Spirilla – the cork screw


       Under favourable conditions, they reproduce by splitting into two. Bacteria are single-cell organisms which bring about decay in dead plants and animals and break them into simple compounds. Bacteria are found everywhere, even in our bodies and it cannot be seen with the naked eye. Certain bacteria are very useful as they cause fermentation and help the milk to curdle.

       They combine with nitrogen and other elements to make some useful compounds for plants. Vinegar and certain antibiotics are also prepared from bacteria. Thus we see that they are both useful as well as harmful to us.

Aztec Civilization 3

1. What was Aztecs’ main occupation?
      The Aztecs made terraces, which were steps descending down a wall to control the flow of water.

      This kept their crops from flooding. Like the Olmec civilization, the Aztecs also used a slash and burn method of farming.

      Chinampas, artificial islands made by weaving giant reed mats and covering them with mudded plants, were used to extend cropping into the swamp. Although they seemed to float, the chinampas were anchored to the ground by plant roots. All this helped the Aztecs grow abundance of corn, chili peppers, squash, tomatoes, beans, and other kinds of food.

2. Briefly describe the pyramids of Mexico.
      The pyramids of Teotihuacan rise as high as twenty-storey buildings, above the central Mexican highlands, with a grandeur and mystery that stirs the imagination and in spires the soul. All of the buildings are aligned with the stars and the solar system from precise survey points located in the nearby mountain range, using an advanced understanding of mathematics, geometry and astronomy. It thrived as the primary center of learning and culture in America for over one thousand years, before it was abandoned about fifteen-hundred years ago. After the fall of Teotihuacan, two major paths of sacred knowledge formed. One Toltec path went to Tula near present day Hidalgo. The magic of Tula can be compared to what our culture might term as “black magic”.
        Uxma Pyramid

        Palenque Pyramid

Thunderstorms 2

1. How much energy does the main stroke of lightning contain?
      The main stroke of lightning contains so much energy that it heats up the air around it. The heat makes the air expand quickly, causing an explosion. This is the loud noise of the thunder.

2. Briefly describe the things struck by lightning.
      Lightning always travels the shortest distance that it can between the cloud and the ground. So, it usually strikes high places, tall buildings or prominent objects such as trees or people.

3. What is smog?
      Smog is a combination of smoke. It forms where air is polluted with vehicle exhaust fumes. There is a complicated chemical reaction between the fumes and the air in the presence of sunlight.

4. What happens when lightning strikes anything?
      Lightning quickly heats up whatever it strikes. When the tree is struck, the water in the tree boils instantly and turns into steam, which makes the trunk explode. We can remain safe by avoiding trees and open spaces during storms.

How does Your Kidney Work?

      The urinary system in human beings consists of two kidneys ureters, urinary bladder and urethra. The reddish brown, bean shaped kidneys are situated at the back of the abdominal cavity, one on each side of the vertebral column.

      The kidneys are made up of large number of coated tube-shaped filters called nephrons. They carry nitrogenous waste material and excess water from the blood and form urine which passes via ureters to the urinary bladder.

      When the bladder gets filled with urine, it is exerted through the urethra by contraction of muscles around the urinary bladder. Waste material removal is important for all living organisms. Normal kidney function is essential for a good health.

When did man discover fire?

      The discovery of fire by man dates back to the Paleolithic Age. Archeological evidences prove that the early man knew about fire. These evidences are in the form of charcoal and burnt remains of bones. In the beginning, man used fire as protection against wild animals and to keep himself warm.

      Historians are of the view that the early man knew the uses of fire even before he came to know about how to make it. Perhaps, lightning struck a tree and the jungle caught fire. Man must have noticed that the wild animals were afraid of the fire. So, he kept it alive. Also, he must have felt warmer near the fire. Then, he must have discovered that the flesh of the animals that burnt in the fire was tastier.

      Then he began to cook the flesh before, eating it. By accident, he also came to know that fire could be made by striking two stones against each other. However, this idea must have come to his mind much later. Some historians are also of the view that the Neanderthal man knew how to make fire.

Fact
      Fire is caused when there is a quick chemical reaction between a fuel, such as wood or petrol and oxygen. Such reactions in which oxygen and other elements are involved are called oxidation reactions.

Mars

     Mars, Earth’s outer neighbor, is the fourth planet from the sun and is the seventh largest. Mars’s bright appearance and reddish color stand out in the night sky. Impressive surface features, such as enormous volcanoes and valleys are frequently obscured by huge dust storms. Though Mars is much smaller than Earth, its surface area is about the same as the land surface area of the Earth.
         Mars

1. Give a brief description about the features of Mars.
     Mars is marked by many interesting features. Some of these features are volcanoes, canyon systems, river beds and dune fields. Of these features, the most interesting include the apparently dead volcano Olympus Mous, which rises 23 km above the surrounding plains and is the highest known peak in the Solar System.

2. Why is Mars called the red planet? Name its two tiny satellites?
     Mars is known as the red planet because of its dusty red surface. The two tiny satellites of Mars, which orbit close to the surface are Deimos and Phobos.
          Deimos

          Phobos

3. Why is there no life possible on Mars?
     There is no life possible on Mars because oxygen, which is no important to us on Earth, makes up only 0.13% of the atmosphere of Mars. There is only one fourth as much water vapor in the atmosphere.

Evolution of plants 5

1. Can one kind of tree produce the fruit of another kind of tree?
     Yes, by the simple method of grafting, which is a technique of attaching the part of one plant to another. There are many techniques of grafting from inserting a single bud under the bark to grafting long twigs across the wound of a tree so that it heals the wound s on the bark.

     Grafting helps produce better quality fruits.

2. How primitive men learnt to grow plants?
     The primitive men living on the Earth did not know how to grow plants. Thus they spent the entire day hunting or gathering fruit and seeds which ripened naturally in the forests. During summer season plenty of fruits and seeds were available while during winter there were plants which had no fruits. Later on, man discovered that there were other plants which can save him from starvation. These were woodland plants with dry fruits which didn’t wither away in winter e.g. hazel trees, chestnuts, oak and walnuts. Many of these types of trees have been found in the lake settlements which revealed that these fruits were important for primitive man. During early times the cave dwellers only gathered barley and wheat which grew in the forests. As these foods could be kept for longer duration, they took these cereals along with them while wandering through the woods, but before proceeding for a journey they always scattered a few grains to impress the almighty. After winter when they went back to the places where they had stayed earlier they were astonished to see that the grains had risen into new plants. Thus they learnt how to grow new plants. Thus cultivation of corn started.


Interesting Fact
     The art of bonsai – Bonsai is the art of keeping a tree to a dwarf size. This art originated in China nearly 1000 years ago but was made popular by the Japanese. Bonsai is a Japanese word meaning ‘tray plantation’. Bonsai pots are usually earthen ware.

Aztec Civilization 2

1. What was the principal food of Aztecs?
     The principal food of the Aztecs was a thin cornmeal pancake called a tlaxcalli. (In Spanish, it is called a tortolla.) They used the tlaxcallis to scoop up foods while they ate or they wrapped the foods in the tlaxcalli to form tacos. They hunted for most of the meat in their diet and the chief game animals were deer, rabbits, ducks and geese. The only animals they raised for meat were turkeys and dogs.

    The Aztecs have been credited with the discovery of chocolate. The Aztecs made chocolate from the fruit of the cacao tree and used it as a flavoring and as an ingredient in various beverages and confectionery.

2. Briefly describe the Aztec Society.
     The Aztec society was divided into three class-slaves, commoners, and nobility.
Slaves:
     The children of poor parents could be sold, usually, for only a certain time period. Slaves could buy back their freedom.
The slaves that escaped and reached the royal palace without being caught were given their freedom instantly.

Commoners:
     The most numerous social group was known as the macehualtin; these people were engaged in agriculture and common trades. Although they worked on the land in family units and were allowed to keep their produce, the land itself was collectively owned by the inhabitants of the neighborhood or calpulli.
     Commoners were given lifetime ownership of an area of land. The lowest group of commoners were not allowed to own property. They were tenant farmers, they just got the right to use the land and never became its owners.

Nobility:
     The nobilities were the people who were nobles by birth, priests, and those who earned their rank.
The warriors, priests, and the nobility were considered to be among the most respected in the Aztec social hierarchy.

     The long distance traders also enjoyed considerable privileges and often served the government as ambassadors and spies. The most outstanding artisans, physicians and truly wise teachers were also highly respected.
              The temple of Sun

3. Describe briefly the gods and goddesses of the Aztec.
     Religion was extremely important in Aztec life. They worshipped hundreds of gods and goddesses, each of whom ruled over one or more human activities or aspects of nature.

     The people had many agricultural gods because their culture was based heavily on farming; it also included natural elements and ancestor-heroes.
     They believed that the balance of the natural world, the processes that make life possible – like the rain or solar energy and that the destiny of people depended on the will of these gods. While some deities were benevolent, others had terrifying characteristics.

     The Aztecs thought that the power of the gods should be acknowledged and thanks given to them, so as to avoid the catastrophes that their rage or indifference could cause. For this reason, monumental ceremonial centers were built and there were so many religious rites.

     The existence of the gods and their goodwill were maintained by offering the most valuable human possession, life. This then, led to the origin of human sacrifice and the ritual of bearing intense physical pain, which believers intentionally caused themselves.

Thunderstorms 1

     During warm weather, huge storm clouds are formed very quickly. The clouds of this kind are full of water and fast moving air currents. These can store powerful electricity to make lightning and thunder.

1. How are the cumulonimbus clouds formed?
     In the hot damp weather, there are lots of tiny invisible droplets, which rise very fast. When these invisible droplets hit the colder air above, they make tall, piled up clouds called cumulonimbus clouds. In this way, the cumulonimbus clouds are formed.

2. Why does the lightning zigzag?
     The lightning zigzags through the air, as it finds the easiest path from the cloud to the ground.

3. How is strong electric charge built inside a cloud?
     Inside the clouds, the water droplets and ice crystals rub together in the swirling air. This rubbing of ice crystals and water droplets cause them to build up a strong electric charge. Some have a negative charge (-) and some have a positive charge (+). The negative charge gets accumulated at the bottom of the cloud, making a huge difference between the cloud and the ground, which has a positive charge.
                   Lightning

4. How does lightning travel when it strikes?
     When lightning strikes, it travels first downwards and then upwards. The first stroke called the leader stroke is invisible. It jumps from the cloud to the ground. This creates a path for the main stroke, which sparks from the ground back up to the cloud.

How does your liver work?

     The liver is the largest organ in the body weighing between 1.36 and 1.81 kg. Your liver works in many ways. You eat protein in various forms both vegetarian and animal in origin and form ‘raw’ proteins. The liver has to create proteins acceptable to the body by first breaking them down and then actually re-building them. The liver also makes certain proteins, such as the blood clotting protein fibrogen.

     The liver turns carbohydrates into two forms. One is ‘instant energy’ in the form of glucose and the other is stored energy in form of glycogen. The liver produces a hormone which can store excess sugar present in the blood as glycogen.
     Fats are also turned by the liver into forms which deposit under the skin (subcutaneous layer) and act as insulation and shock absorber. Bile is a thick yellow or greenish fluid made in the liver. It neutralizes the acidity of partly digested food in the intestine so that enzymes can continue to work in the intestine.
     The liver is also a storage organ. Several vitamins, iron (removed from blood pigment, etc) are stored in liver. The liver also neutralizes poisons and wastes.

Where were nuclear weapons dropped for the first time?

     Nuclear weapons are the most powerful and destructive weapons. USA was the first nation to develop such powerful weapons. When a nuclear weapon id dropped, a huge amount of energy is released.

     Chain reaction takes place and it continues for a millionth of second. Towards the end of World War II, on August 6, 1945, The USA dropped a nuclear bomb on the Japanese city of Nagasaki. This bomb was a gun type weapon. It contained the energy of about 15 kilotons of TNT. Three days later, on 9th August, another bomb was dropped on Hiroshima, another Japanese city.

     This bomb had energy of about 20 kilotons of TNT. The effect of these bombs was terrible. Thousands of people lost their lives. Many became handicapped. Even the unborn babies were affected by the impact of these bombs. This incident shocked the entire world. It was an important turning point in the history of warfare. Nuclear bombs became a threat to humanity.

Fact
     The nuclear bomb dropped at Hiroshima was called ‘Little Boy’ and the bomb dropped at Nagasaki was called ‘Fat Man’.