What are life processes?

Life Process

life processes

Living beings are self-regulated and self-organized cell-based entities that show the various characteristics of life. The major and most apparent of these characteristics are movements. Movements are of two types-visible and invisible.

Visible movements are changes in the position of organisms or their parts-running dog, a yelling class-fellow, a flying bird. Even in sleep, one can observe breathing movements. However, plants do not show such apparent movements except in a few cases like Mimosa pudica (Sensitive Plant). Most plants show very slow movements of growth, bending, etc..

Invisible movements occur at the level of molecules. Every cell receives nutrients and passes out wastes. It obtains energy by breaking down nutrient molecules. The energy is then used in repairing and maintaining the cellular structures.

Viruses are called semi-living because they are lifeless outside the host cell. Inside the host cell, they show movements of their molecules.

What are life processes?

Life processes are those activities and functions of living beings that are essential for their maintenance and survival. They are the basic functions that are similar in all organisms.

  1. Energy –Maintenance processes prevent damage and breakdown of protoplasmic structures. For this they require energy which comes from food.
  2. Nutrition – It is procuring of food for obtaining energy, body building and repair materials. Food for body building as well as release of energy is carbon-based oxidation-reduction process. Plants prepare their own food. Animals obtain food from outside. In the body of an animal, the ingested food is first broken into simpler form for absorption by cells. The cells elaborate the simple nutrient molecules into cellular components as well as energy yielding components.
  3. Respiration – It is the energy yielding process of the living body. Energy is released when a carbon based energy storing complex (e.g.. glycogen, starch, glucose) is broken down in the presence of oxygen (aerobic respiration). It can also occur in some cells and organisms in the absence of oxygen (anaerobic respiration).
  4. Exchange of Materials -There is a regular exchange of materials between the organisms and their environment. Most organisms obtain water, oxygen and nutrients from their environment. In return, they give out carbon dioxide, waste products and undigested matter. Single celled and other simple organisms are in direct contact with environment. Therefore, they directly obtain food and exchange materials with the same. Generally it is through diffusion. In complex multicellular organisms very little exchange occurs through general surface. They have developed special organs for respiration (exchange of gases), ingestion, digestion and egestion.
  5. Transportation – Multicellular organisms require a transportation system as cell to cell diffusion is a very slow process with billions of cells forming the bulk of the body. Transport system can take the required material in short span of time to all parts of the body. In animals, blood and lymph form transport system. In plants, vascular strands (xylem and phloem) do the same job.
  6. Excretion – It is the expulsion of waste materials from the body. Waste materials are the by-products of metabolism which are often toxic if they accumulate in the body, e.g., urea, uric acid. They are collected from all parts of the body by circulatory or transportation system and brought to the organs where they are separated for elimination. In plants, an excretory system is absent. They convert their waste products into harmless form and store the same in the dead tissues and senescent leaves.
  7. Movements – Molecular movements (invisible movements) are essential for working of the body cells. Visible movements are required for supporting life.
  8. Sensitivity – Every living organism, small or large, is sensitive to changes in the environment.