for touchstone 2011

The Living World

Raghubar Shrestha
Associate Prof. of Zoology,
HoD, Biology Department

Plants and animals have been surviving on this earth for time immemorial. They had different forms, shapes and structures. They are all, the part of the living world. They are all living a life and one question is often asked. What is life? It’s very difficult to answer. However, biologists have come across the suitable answer to this question. Life can generate energy within its body, use energy for carrying out various activities. Living things move about except the developed plants. They grow in size, take food, respire, excrete, undergo reproduction, and respond to the external stimuli. The use of energy within their body is in various forms like heat energy to keep their body warm. Certain fire worms can produce light, certain fishes can produce electric current. Most of the vertebrates can produce sound energy. On the other hands, non living things cannot use energy. Still it cannot be said that, non living things do not have energy. We have the example from the ancient period. Just by striking two stones, the ancestors of man produced fire. The stone at the top of the mountain has the potential energy. Similarly , the water in the pond has potential energy. Any time, the stone and water can go into movement and potential energy is changed into kinetic energy. The non living things move on and on until a force is applied to stop them.

When living things move, they can stop by themselves. They have internal force which can stop them from moving ahead. The life can be compared with some sort of movement. To remain idle is nearly death. The young children move here and there the whole day. More the movements, there is more life, many years to live. As we grow, movements slow down and down. At the very old age, the movement is very less and it means the death is very much near.

Before we born, or say, before we start our life, the sperms swim around the relatively stationary ovum. The sperms are always in movement. It is due to movement that the sperms find ovum and one of the sperms quickly fertilizes it. After the fertilization, the zygote is formed in all sexually reproducing organisms. This is the beginning of the life. Not only living things, the stars, the planets, the moons in the space are all the time in movement. In the smallest particle, the atom, we can see the electrons are in movements. The electrons are moving around the nucleus in their own orbit. The water, the air what are not in movement?
Inside the body of living organisms, the heart is pumping blood twenty-four hours a day. The circulation of blood is associated with life. Once the circulation of blood is ceased, there is no life. Similarly, the breathing movements are continuous process. At different parts of body, muscles are present. They can contract and expand. Actually, these muscles help in the movements of fluid and waste materials from one part to another part of the body. Because of such movements, urine and undigested wastes etc can be discharged from the body. Similarly, the sperms and ova in male and female are carried down the duct system for fertilization. The muscles contract and expand to secrete the juices and enzymes in the body so that foods can be digested properly. During the proliferative phase in the menstrual cycle in females, there is contraction in the wall of uterus which can help in the ascending movement of the sperms to find the ova. In the working of nervous system, the impulses are carried at the faster rate along the nerve fiber to the brain and various information from brain to the target organ. All these are one or other form of movements.

Again, not only the movements in side body, the muscles help in the movement of parts of the body or whole body, which is the external movement. The movement or locomotion of these animals are needed to find their food, to protect themselves from various types of enemies, to move to suitable environment as well as to find the sexual partner and to find the safer place to rear their young ones. They cannot remain moving here and there. In wild animals, they need certain area to move about for their reproduction. Still, many fishes and birds migrate for months and to a longer distances. Such migration in these animals are of great importance to get all the available facilities for proliferation of their race.

Besides, in the birds and mammals, there are movements used for communication among the members of various animals. In the Primates of Class Mammalia like monkeys, apes and man, facial expressions are seen. They can actively show the expression of happiness or sorrow by facial expression. For this, there are number of muscles in their face. By the movements of these muscle, the facial expression is possible. The eye movements are so important in communication that one can read the eyes to know many things. The blinking of eye is necessary for proper functioning of eye. Inside the ear of animal, there are three ear ossicles namely malleus, incus and stapes. They are heavily built and joined like in the lever. By their movements, magnify the sound waves and pass to the internal ear. Such movements help in the process of hearing. The movements in the parts of our body can help a great in the non verbal communication.

Though, we cannot see the locomotion in higher plants like the trees, bushes and herbs, there are the movements of water as well as of food they prepare in their leaves from one part to another part of their body. Transpiration is a continuous process, in which plants absorb water from the soil and excess water is lost from the leaves in the form of vapor. Most of the plants usually move towards the source of light. They need the light for manufacturing their food. Photosynthesis is the process in which plants absorb CO2 from atmosphere and water from soil and then in the presence of light chlorophyll can manufacture food.
In case of plants, the movement or transfer of pollen grains into the stigma of gynoeceium in the same flower or to the other flower in the another plant, is assisted by air, water, honey bees or other animals. There will be no fertilization and growth in plants without such movements.

In the non living things also, there are movements. The electric current moves from higher potential to lower potential. The air is always moving from higher pressure to lower pressure. The moving air takes the clouds from one part to another part. There is the water cycle. The water evaporates from the sea, clouds taken to the mountains by air and causes rainfall. The water in the brooks, rivers etc are always running which can support various lives at different parts of the world. Not only these, there are Carbon cycle, Nitrogen cycle, Phosphorus cycle etc. all these chemicals are moving from one part to another part helping all the living animals and plants in their survival.

Speed of some of the living and non living objects

Light 299792.458 Kilometer/second
Concord jet 594.44 meter/second
Sound 340.29 meter/second at sea level
Nerve impulse 120 meter/second
Fast train 111.1 meter/second
Cheetah 31.1 meter/second
Usual speed of running being 22.2 meter/second
Motor cycle 11.1 meter/second
A brisk walk of man 1.1 meter/second

A Rocket needs a velocity of 11.2 Kilometer/second to leave the earth if projected directly at perpendicular to the earth surface. From the above table, it seems that light travels the fastest of all, far more than that of Rocket. But still, the human mind can travel faster than the light.

The Sun, the various planets like Earth, Jupiter and Saturn etc are moving in their own orbit to balance the gravitational force. As the Earth goes round the Sun, there are the days and nights and different seasons throughout the year. The plants and animals have various activities according to the day length and different seasons like winter, spring, summer and autumn etc. They become inactive during winter and summer and active during spring, rainy season and autumn.

From all the things above, it is obvious that the life and movements are so much associated that there will be no life without movements in living as well as non living things. The movement is a kind of kinetic energy. All the living organism live using one or another form of energy and the movement or locomotion is of great importance in the act of living in this world.