What is Photosynthesis?


            Photosynthesis is the process by which green plants make food for themselves and indirectly, for all animals, including human beings.



            In photosynthesis plants combine water and salts in the soil, and carbon dioxide in the air to build up organic compounds, such as sugar starch and proteins. To do this they use the energy of sun light, which is absorbed with the help of the green dye in their leaves called chlorophyll.



            This process of manufacturing food from what they absorb through their roots and leaves make green plants the primary food producers in the world. All animals draw their nourishment from them, either by feeding on plants themselves or by eating other animals that do so. During photosynthesis, which takes place only in daylight, excess oxygen is produced and released into the atmosphere for animals to breathe.



            After the Second World War, the American scientist Melvin Calvin wrote a book about how plants capture the carbon dioxide in the atmosphere. In 1961 he received the Nobel Prize in chemistry in recognition of his work.



Picture credit: google


Why are vampire bats dangerous?


          Vampire bats are dangerous because they carry rabies and other diseases and infect their victims as they suck the blood which is their only food.



          Vampire bats (Desmodontidae) are found only in South and Central America. They have extremely sharp teeth and pierce the skin of their prey so gently that the victim does not awaken. Blood is drawn into the mouth by the almost tubular tongue and the vampire bat’s whole digestive system is specially adapted for his diet of blood.




Picture credit: google



Where would you find a red Giant?


            You would find a Red Giant on the Sierra Nevada Mountains of California in North America. It is a huge redwood tree, called a giant sequoia. These trees, members of the conifer family, are the largest in the world and grow to a height of 300 feet. They have a very hard, reddish brown wood and a thick, very rough bark. The giant sequoias were believed to be the oldest living things in the world. The ring marks on the stumps of the oldest trunks have been carefully counted and it is now known that some of the biggest are about 4,000 years.



              Many of these trees were cut down for their timber, which is resistant to attacks by fungus, and termites and other insects. To preserve the remaining groves of these huge redwoods, a reservation called the Sequoia National park was set up in 1890. The largest tree there is 272 feet high and has a circumference at the base of its trunk of 101(1/2) feet. Its weight has been estimated to be over 6,000 tons.



           Some of the other trees are taller but do not have such large trunks. A tunnel has been cut through the base of one of these giant trees which is big enough to drive a car through.



Picture credit: google


What are fossils?



          Fossils are the remains, moulds, traces or impressions of prehistoric animals and plants found in the ground. The word comes from the Latin fodere meaning to “to dig”, and originally meant any old, curious object dug out of the earth. But since about the middle of the 16th century, fossils have been regarded specifically as hard objects showing evidence of earlier forms of life, often many millions of years old.



       There are many kinds of fossils. Some are footprints which strange prehistoric animals left behind in mud long since turned to rock. Others are stones which were ones soft substances, but still preserve the outlines of extinct plants, or of seashells, or of the bodies of animals. Sometimes even the bones of creatures have survived.



      The study of fossils, which is called palaeontology, has enabled scientists to fill many vital gaps in the history of the world and its inhabitants. For example, fossils have shown that rocks in great mountain ranges like the Alps or the Rocky Mountains were once below the surface of the sea. They have indicated that the United States and Europe were once covered by tropical forests. Also, they provide evidence of the common ancestry of animals which today differ widely in appearance.



      The subject can be rewarding hobby for amateurs. Many important contributions to the world’s great collections have been made by people who looked for fossils in their spare time or even came across fossils by sheer accident.



Picture credit: google


Where would you find a trap-door spider?


Trap-door spiders are to be found just under the surface of the earth. They belong to the class of spiders called mygalomorphae which includes the bird-eating spiders of the tropics. All these spiders tend to be rather large. They have four lungs instead of two, and their jaws work vertically instead of sideways.



     The trap-door spider has perfected the art of burrowing underground. Its jaws are provided with a special row of teeth with which to dig out its home. It lines its burrow with silk and makes a trap-door consisting of layers of silk and earth. The outside of this door is coated with moss or some other form of camouflage. The spider lies in weight behind its trap-door, darting out to seize its prey.



    Trap-door spiders are wide-spread throughout the hottest regions of the world, with comparatively few in the temperature zones. Specimens of up to four and a half inches have been found. It is estimated that some may live up to 20 years.



Picture credit: google


Why do birds have different bills?


The shape of a bird’s bill or beak is closely related to the kind of food it eats and the way in which it collects or catches this food.



    A crow or jay has a strong all-purpose bill, capable of killing small mammals but fine enough at the tip to pick up small insects. Many songbirds have slender bills for picking up insects from leaves or out of cracks; others have wide flat ones for catching flies or strong thick one for cracking seeds and nuts.



    Birds which dig for worms usually have long bills with sensitive tips while many water birds have broad dredging bills. Divers and grebes have straight spear-like bills and the birds of prey have strong hooked bills for tearing flesh.



    Birds which catch insects on the wing (nightjars, swallows etc.) have tiny beaks but an enormous “gape” by comparison.



Picture credit: google


When does a tadpole become a frog?


Frogs’ eggs become tadpoles within two weeks of being laid in the water, but tadpoles may take anything from two months to three years to change completely into frogs.



      The time taken seems to depend on the environment. Tadpoles will generally develop faster in warmer waters. Also the more advanced species of frog have simplified and shortened the process of transformation.



    Tadpoles, like fish, breathe through gills. They develop lungs during the change-over, gain legs and loose their tails. Their diet changes, too-tadpoles live on plants in the pond, but frogs live on very small insect.



Picture credit: google


What are termites?


Termites are soft-bodied insects belonging to the family Isoptera. They are sometimes called “white ants” but they are like ants only in that both species live in social colonies. They live in the tropics and temperate. Countries and make various kinds of nests below the ground, but the most spectacular are large structures built above ground called “termitaria”. They are built from earth excavated below ground and cemented together by saliva. Some of these nests are 20 feet high and almost too hard to break open even with a pickaxe.



      The termite community is divided into four groups, but only two can breed. Each colony is founded by a “royal pair” and the queen’s life is devoted to laying eggs.



Picture credit: google


Where are the largest animals found?


Blue whales are the largest living animals. They are cosmopolitan creatures and are found in most of the seas, from the polar caps to the equator. Normally those which inhabit the colder seas will migrate to warmer waters in winter.



    Their dimensions are almost beyond belief. Although figures can never be quite accurate, a blue whale can weigh more than 200 tons and many have been found measuring over 100 feet in length. The tongue alone, of a female whale found in Antarctica, weighted well over four tons.



      It has been estimated that in the 1930s there were nearly 40,000 blue whales in the world. But by the end of the 1960s there were fewer than 1,000 alive. This was because for the misdirected efforts of over-zealous hunters.



Picture credit: google


Why do flowers have sepals?


The sepals of a flower protect it while it is in bud. The flower is really a kind of shoot, In which the leaves have been altered so that they can take on the task of producing seeds.



    In a simple flower these leaves are arranged in circles, called whorls. The outermost are five green, leaf-shaped sepals. Inside these are five petals, usually heart-shaped, each with a small flap at its base where nectar is produced to attract bees and other insects.



     Both the sepals and the petals are attached at their bases to the “receptacle”, the swollen end of the flower-stalk, which looks like a cone in the middle of the flower.



    Above the sepals and petals are the parts of the flower used in reproduction. These are the stamens, which contain the yellow pollen, and the carpels, which contain the ovules.



   Most flowers are built on this plan but there are wide variations in size, shape and colour, and in the numbers of the different parts of the flowers.



Picture credit: google


Where did all the dodos go?


The dodo was rather a stupid bird. Indeed, it was so stupid that it was named dodo by the Portuguese when they discovered Mauritius-its home-in 1507. The Portuguese word doudo means stupid.



    Mauritius is an island, 720 square miles in area and lying 500 miles to the east of Madagascar in the Indian Ocean. Until the arrival of man, with his attendant creatures such as the cat and dog, the dodo had been able to live in peace. It had no enemies, which was fortunate because it was big and clumsy and was completely unsuited to fleeing from danger. Its short legs were almost incapable of supporting the weight of the fat, round bocy (about the size of a swan’s) and the ridiculously inadequate, stubby wings were of no use for flying.



    Within 180 years of its discovery by the Portuguese, the dodo was extinct. Over the intervening years several were brought to Europe alive, and one was to be seen in London in 1638. By 1680 the dodo had succumbed.



   With the help of drawings and by the collection of bones gathered in Mauritius has been made of the poor bird. It can be seen at the Natural History Museum in London.



    Mauritius is the only place in the world where the bird is known to have existed. A similar Island of Rodriguez, but this also has become extinct.



    The phrase “as dead as the dodo” is used to mean that something is very dead indeed.



Picture credit: google


When did Pterodactyls live?



Pterodactyls (or pterosaurs) lived between 150 million and 70 million years ago. These extraordinary reptiles were able to fly. Some had a wing-span of over 25 feet, making them by far the largest flying animals known to man. Their skulls were often longer than four feet.



     Unlike the birds, their descendants, pterodactyls must have been unable to perch upright. They probably hung upside down like bats when sleeping or at rest.



     Since most remains of pterodactyls have been discovered among marine sediments, it seems likely that these flying dinosaurs found their food in the sea, like seagulls, by diving for fish.



Picture credit: google




 

What do birds of prey eat?


Birds of prey are those that feed wholly or mainly on meat taken by hunting. They catch other birds, and small animals, for their food.



    There are two chief families, the hawks and the falcons. The hawks include eagles, such as the bald eagle (symbol of the United States) and the golden eagle. The falcons are smaller but share the same general characteristics-hooked beaks, keen vision and outstanding powers of flight. Owls, also. Feed on flesh.



    Besides being fast flyers, many birds of prey are expert at gliding and hovering. Their principal strategy of attack is the “stoop”, when from a great height they sight their prey, close their wings and swoop upon the victim. This manoeuvre calls for a combination of speed and last second breaking unique to this type of bird.



    In advanced countries birds of prey have suffered severely from the effects of poisonous agriculture sprays which have polluted their food sources. This has threatened their survival. But the danger has now been recognized, and in many areas their numbers are slowly recovering.



Picture credit: google


Where does a bee keep its sting?


A bee keeps its sting at the end of its abdomen. At the tip of a bee’s abdomen is a shaft where is stinging thorn is to be found. It can sting several times, but once it leaves the thorn in its victim’s flesh it will not be able to sting again.



    It is not true to say that a bee will automatically die once it loses its thorn. Only female bees can sting. Male bees, or drones, lack this means of protecting themselves.



     There is a species of which even the female cannot sting. But these bees which live mainly in Africa and South America are not defenseless. If disturbed, they will fly at he intruder in great numbers, crawl into his eyes, ears and hair and smear him with a sticky substance, causing him to retreat in great discomfort.



Picture credit: google