Category Biology

Why do bats make high-pitched sounds?

Bats use high-pitched sounds to find their way about. They are nocturnal animals. That is they move about by night. So they have developed their hearing to such an extent that they can find their way by a method known as echolocation.

     The blind-flying abilities of bats were first studied by LazzaroSpallanzani (1729-1799). He surgically removed the eyeballs from several bats to prove that they did not need to see to fly.

    In the 20th century, biologists, using electronic instruments, have carried out experiments with bats. They have discovered that bats find out where to go by emitting high-frequency sounds and receiving the echoes as they bounce off objects. Most of the sounds have too high a frequency to be heard by the human ear.

    Bats commonly fly together in groups, but apparently they are not confused by he sounds and echoes produced by each other. When hunting in woods and in the rain they are able to discriminate between the faint echoes bouncing off the ground, tree-trunks, branches, twigs and raindrops.

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Why are fertilizers used on farms?

Fertilizers are used on farms to increase crop yields by ensuring that soils contain the chemical elements required by growing plants. These chemical elements include oxygen, carbon, hydrogen, nitrogen, phosphorus, potassium, sulphur, calcium, magnesium, and iron. If soils are lacking in any of these, the deficiency can be made good by the right fertilizer.

     Until the 119th century, farmers relied mainly on the application of natural fertilizers put “goodness” back into the land. They used manure from the stock-yards and, in the case of coastal areas, seaweed from the shore. Lime was also applied to prevent acidity. This method of soil rejuvenation went a long way to maintain the presence of chemical elements. But it often did little to improve soils already lacking in certain chemicals.

      Nowadays soils are analyzed to find out deficiencies which can be made up by the application of the appropriate chemical fertilizers. Of course, the chemicals alone do not guarantee a successful crop. The continued application of the natural fertilizers, such as manure and humans (decayed vegetables matter) is also essential.

Picture credit: google

Why do some plants capture insects?

 

 

           Some plants capture insects and other tiny animals and use them as food. They do not devour their prey by chewing but decompose them in a mixture of enzymes. The pitcher plant attracts an insect to its large showy leaf by means of sweet-smelling nectar. The leaf has a treacherous lip which precipitates the unwary victim into a deep hollow pitcher full of digestive “broth”, which soon decomposes its body. Other plants, like the Venus’s flytrap, snap their leaves shut on their prey as it prowls about the trigger hairs glistening with drops of nectar. The sundews secrete a sticky fluid.

Where does a leech feed?

      Leeches, which are rather slimy worms and vary in length from an inch to several inches, have two suckers, a big one at the rear and a smaller one at the mouth end. They have powerful muscles which enable them to expand and contract their bodies.

      This makes them excellent swimmers. They can also use their suckers to crawl on the land in tropical Asia, the island of the Pacific and the Indian Ocean, there is a particularly vicious and dreaded species of land leech which enters the breathing passages of animals, gorges on the animal’s blood and swells so that it cannot escape.

     Aquatic or water leeches cling to fishes, turtles and shell fish. Some leeches feed on earthworms and frogs’ eggs. Others live on the larvae of insects and even on the microscopic life on the floor of the pond.

     Leeches have been used in medicine from early times until quite recently to draw blood from a patient.

What is a loofah?

A loofah is a fibrous, cylinder-shaped vegetable product often used in bathrooms as a kind of rough sponge or gentle brush. It is the dries interior of the fruit of a plant known to botanists as Luffa aegyptiaca. Less dignified, though more descriptive, names for this tropical climbing or trailing herb are dishcloth gourd and vegetable gourd.

     The Luffa belongs to the great gourd family of plants, and its 800 relations include the cucumber, the melon and the pumpkin. In spite of having an unpleasant smell, the Luffa is cultivated in Egypt (hence the second part of its Latin name) and in Arabia, India and china. The yellow-flowered climbers can sometimes be seen adorning the trunks of palm trees. Besides being used to make loofahs, the luffa’s fruit is eaten in curry.

     The development of man-made materials has led to a decline in the loofah’s popularity, but many people still use its slightly abrasive qualities to stimulate the skin.

Where does the breadfruit tree grow?

      The breadfruit tree is found in the South Pacific Islands and, to a lesser, degree, in other parts of the tropics. It is an extremely handsome tree, growing up to 60 feet high. The oval leaves are a pleasant, glossy green and quite large.

      There are two distinct forms of breadfruit, one seedless and the other containing many seeds which, when boiled or roasted, taste much like chestnuts.

   The breadfruit, which contains a considerable amount of starch, is not really a fruit in the popular sense and is rarely eaten raw. It can be boiled or baked, served with salt, butter or syrup, and even sliced and fried like potatoes.