Here is your Free essay on Life

All the organisms perform some basic functions to keep themselves alive. The basic functions performed by living organisms to maintain their life on this earth are called life processes.

The basic life processes common to all the living organisms are: Nutrition and Respiration; Transport and Excretion; Control and Coordination (Response to stimuli); Growth; Movement and Reproduction. The process of nutrition involves the taking of food inside the body and converting it into smaller molecules which can be absorbed by the body.

Respiration is the process which releases energy from the food absorbed by the body. Transport is the process in which a substance absorbed or made in one part of the body is moved to other parts of the body. Excretion is the process in which the waste materials produced in the cells of the body are removed from the body.

Control and coordination (or response to stimuli) is a process which helps the living organisms to survive in the changing environment around them. The process of growth involves the change from a small organism to a big organism (or an adult organism). In movement, the organism either moves from one place to another or moves its body parts while remaining at the same place. The process of reproduction involves the making of more organisms from the existing ones, so that organisms could live on this earth forever.

Energy is needed for the Life Processes:

All the living organisms need energy to perform various life processes. They get this energy from food. Food is a kind of fuel which provides energy to all the living organisms. The living organisms use the chemical energy for carrying out various life processes. They get this chemical energy from food through chemical reactions. Actually, living organisms continuously need energy for their various life processes and other activities which they perform.

For example, energy is required by an organism even during sleep. This is because when we are asleep, a number of biological processes keep on occurring in the body which requires energy. Our heart beats non-stop even when we are asleep to pump blood throughout the body. And this beating of heart requires energy. Thus, the working of heart requires a continuous supply of energy.

The energy required by an organism comes from the food that the organism eats. Thus, food is the basic requirement of all the living organisms for obtaining energy. In this chapter we will first study the process of intake and utilisation of the food by an organism (called nutrition) and the liberation of energy from the food (called respiration).

After that we will study the process of moving the digested food and other materials to the various parts of the body (called transport) and the removal of waste materials from the body (called excretion). Let us start with nutrition.

Nutrition:

Food is an organic substance. The simplest food is glucose. It is also called simple sugar. A more complex food is starch. Starch is made from glucose. The general name of substances like glucose (sugar) and starch is ‘carbohydrates’. Carbohydrates are the most common foods for getting energy.

Fats and proteins are also foods. (A wider definition of food, however, also includes mineral salts, vitamins and water which are essential for the normal growth and development of an organism). The process of taking in food (consuming food) and utilising it is called nutrition.

It is a process in which food is obtained in order to utilise it to provide energy for performing various metabolic activities of the organism. Actually, the term ‘nutrition’ comes from the word ‘nutrient’. A nutrient is an organic or inorganic substance required for the nutrient can be said to be a particular type of food.

A nutrient can be defined as a substance which an organism obtains from its surroundings and uses it as a source of energy or for the biosynthesis of its body constituents (like tissues and organs). For example, carbohydrates and fats are the nutrients which are used by an organism mainly as a source of energy whereas proteins and mineral salts are nutrients used by an organism for the biosynthesis of its body constituents like skin, blood, etc.

The food taken in by an organism contains a large number of nutrients like carbohydrates, fats, proteins, minerals, vitamins and water, etc. We can now say that: Nutrition is a process of intake of nutrients (like carbohydrates, fats, proteins, minerals, vitamins and water) by an organism as well as the utilisation of these nutrients by the organism. We will now describe the various ways of procuring food (or obtaining food) by the different organisms. In other words, we will now describe the different modes of nutrition of the various organisms.