Category Plants & Animals

How do plants take and make their food?

            It is a well-known fact that trees and plants are also living beings like humans. They need food, water and air for survival. It is interesting to know how they take their food.

            Plants derive their food both from the earth and the air. If you minutely look at their roots, you will find that the ends of these roots are like fine fibres. We call them root-hairs. They absorb water and minerals and transport them upwards to the leaves through the trunk and the branches. It is the leaves which prepare the food.

            The leaves have pores which are filled with air. They also have a green colouring matter called chlorophyll. This chlorophyll acts as a catalyst, and uses carbon of the carbon dioxide and the hydrogen of the water present in the leaves to make carbohydrates (sugars). In this process oxygen and water are given out which are excreted by the leaves of plants.

            Sugar is further converted into starch. From these carbohydrates, the plant can build up complex substances as foods which it needs for its life and growth. These substances include proteins, juices, oils (fats) etc. The water from which the plants take hydrogen for photosynthesis contains dissolved minerals needed in building various parts of the plant body. These are chiefly the compounds of nitrogen, sulphur, phosphorous, sodium, calcium, magnesium, iron etc.

            Food not immediately needed for growth is stored in the plant including its seeds, fruits, tubers or bulbs. This accumulated food in the seed is used in its germination.

 

How do animals and pants survive in deserts?

            Due to the scarcity of water and particular climatic conditions (hot, dry, windy) prevailing in the desert, it is very difficult for animals as well as plants to survive. Nonetheless, we do find some of these. These are adapted to the desert conditions. Let us see what types of vegetation and animals are found there and how do they survive.

           The vegetation of a desert is mainly thorny shrubs, cacti and palm (especially date) trees. Cacti and other desert plants have adapted themselves to live in desert conditions. They have evolved ways to store water in their fleshy stems. The leaves have squeezed themselves into tiny thorns to reduce the loss of water. The roots go deep into the ground and are wide spread to collect every drop of water available. The stem stores the water and slowly gets thinner as the water gets used up. In some cacti the thorns are pointed towards the earth. The dew drops deposited on the ends fall on the earth hence moisture is maintained below the cacti. There are quite a few animals found in deserts such as snails, pack rat, jerboa, etc. Most desert animals sleep during the day to escape the day temperature and they come out in night in search of food. Some animals sleep during the hottest part of the year. Animals such as kangaroo, rat and gerbil can survive with little or no water. Reptiles adjust their body temperatures to cope with heat and cold. The Australian desert toad stores water in its body. Some lizards, ants, owls and snakes also live in deserts. 

 

How do some creatures make a shell on their body?

             You must have heard the sound of conch (shankh) blowing in the temples. You must have also seen big and small conches at sea-shores and on the river banks. Some conches are so small that they can be seen only with the help of a magnifying lens, whereas there are others as big as measuring up to 120 cm.

              Do you know what these conches are and how they are formed? They are the body shells of aquatic creatures. These creatures are called mollusks. Some 60,000 species of the mollusks have so far been studied by the scientists. As the size of the mollusk increases, the outer shell also increases and becomes harder. They are made up of calcium carbonate (lime). The mollusk collects lime from the sea water and deposits it in its outer shell. When the mollusk dies, the shell floats and comes to the surface of water.

              The shell of the mollusk has three main layers. The outer layer of the shell is made up of smooth material like the oyster and contains absolutely no lime. The layer below this i.e. the second layer is made up of calcium carbonate. The lowest layer that is the third layer is a group of many thin layers, which are made up of oyster-like material and calcium carbonate. The conches are of many colours. They have many stains and stripes. These stains, colours and stripes have their origin in some colourful materials present in the glands of the mollusk. These colours, stripes and stains enhance the beauty of the conches.

              The conches not only protect the mollusk, but they are also very useful for us. In ancient times people used mollusk shells as coins. Small conches are even used as part of necklaces. They are used as decoration pieces in homes. Buttons are made from small shells. Aquatic animals with shells have been existing for billions of years. After their death these shells deposit themselves on the sea-bed which forms rocks of limestone. 

Is Bamboo a tree or grass?

             Majority of people believe bamboo to be a kind of shrub or plant. In fact, it is neither. It is a type of grass. It can reach a height of about 35 metres and upto a thickness of about 30 cm. It has many varieties. About 600 species of bamboo have been studied. All kinds of bamboos have smooth, hard and strong trunks. The rate of their growth is very fast. It can grow up at the rate of 40 cm a day. One bamboo reportedly grew 90 cm in 24 hours. Some bamboos blossom only once in 30 years. Others may take 100 years to blossom. A bamboo plant dies after it blooms. The seeds from these blossoms grow into new plants.

            It is only the stem of the bamboo grass that is of most use in the construction of roofs, huts, walls, houses, etc. It is used to make mats, baskets, musical pipes, paper, as a fishing rod and weapon for defence; it is cooked as vegetable and pickle is also made of them; some medicines are made from a fluid in the stem joints of bamboo branches. Its hollowed stems are used as water pipes especially in Japan.

            It is found in abundance in South-East Asia, Indian subcontinent and the islands of the Pacific Ocean.

 

What is regeneration?

Would it not be wonderful if people who lost an arm or a leg or even a finger in an accident could simply grow another one in its place? But in reality it does not happen so 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 same point from where the original limb has been lost. Development of a new body part in place of a lost one is known as regeneration.

If a small arm of a starfish is cut off or destroyed, it is regenerated. The hydra, lizards, sponges, newts and earthworm also possess this capability of regeneration.

The ability of regeneration is different in different creatures. Living beings with complicated structures have lesser ability of regeneration. Man and other mammals have a complex constitution. That is why they have lesser ability of regeneration. Mammals can replace hair, nails and skin. Mammals can also repair broken bones and other damaged tissues. Regrowing of the wings of birds is another example of regeneration.

In some species new tissues grow from the surface of the wound replacing the lost or damaged tissues. Sometimes, the tissues that an organism regenerates are different from the original ones. The regenerated structure may be smaller and weaker than the original one.  

What are bacteria?

               Bacteria belong to the lowest category of plants. They are unicellular micro-organisms. They are as small as 25,000th part of an inch. Some of them are even smaller and cannot be seen with the help of an ordinary microscope. They reproduce through the process of cell division (fission) i.e. one cell divides itself into two. Under favourable circumstances the rate of their reproduction increases. Within twenty minutes the cells of the new bacterium divide into two, in forty minutes one bacterium multiplies to four and to sixty four in two hours. In this way, in twenty-four hours, one bacterium multiplies into 4,000,000,000,000 bacteria. If the rate of the reproduction of bacteria remains the same, the weight of the bacteria produced within 72 hours will become 33,000 times more than the weight of the earth. But this is impossible because in the struggle for food and water only one percent of them can survive. They may live in soil, water, air or in any other organisms.

               Bacteria can be broadly classified into four types. Some bacteria are round, they are called coccus. The rod-shaped are called bacillus, spiral-shaped the spirillum and the comma-shaped vibrio.

               Bacteria are both harmful and useful. They spread many diseases in human beings, animals and plants. Typhoid, tetanus, T.B., cholera, diphtheria, dysentery, whooping cough etc. are some of the well-known diseases which are spread by bacteria. But, on the other hand, some bacteria are very useful for mankind. Conversion of milk into curd is done by bacteria. They destroy the dead plants and animals by setting decay in them. Vinegar is also prepared by them. It is the bacteria which make yeast for bread, and colours the hides (animal skin). Certain antibiotics are also prepared by using them. Thus, bacteria are both useful and harmful to us. Antibiotics and sulpha drugs are used to control bacterial diseases.