LIFE

Life is unique, complex organizations of Cell and Cellular contents that show various types of functions and processes to bring the life existence.

OR

Life is unique, complex organization of atoms, molecules and compounds, which perform several chemical reactions for the existence of life.

LIVING

Passing through or going through the life processes and function due to several chemical reactions is called Living.

Characteristics of living organisms

1.      Individuality.

Each living organism has its own unique presence, which cannot be divided further into more independent parts.

E.g. a dog has its individuality from rest of the animals due it own unique Morphology (how the organism look from outside or it appears.

2.      Definite shape and size.

Every organism has definite shape and size which help in the recognition of the organism.

3.      Organization.

Organization refers to the level of arrangement of the component which results in joining one after the other for higher and complex hierarchy (Order of arrangement).

4.      Homoeostasis.

It is the ability or potential of the organisms to maintain the internal environment favourable, constant and stable despite the all time changing surrounding environment. Homoeostasis is important for the proper functioning of the cell and cellular function.

5.      Protoplasm.

It is semitransparent jelly like viscous (highly dense liquid [like honey]) Semifluid complex Organic matter present in all living cells of the organism.  All body function and properties of life are actually due to protoplasm (nutrition, growth, respiration, Etc.).  Protoplasm is also called LIVING MATTER.

6.       Cellular structure.

The body of all type organisms in made up of one or more cells. Organisms are called unicellular if it is made up of one cell. Metazoans and Metaphytes (both means Multicellular) are made up of many numbers of cells.

7.      Genetic material.

All organisms have Genetic or Hereditary material in the form of DNA in the nucleus of the cell. It is related with expression of the traits (characters) in the organism, transmission of traits from parents to offspring (Childs or babies) and to maintain continuity from one generation to the next.

8.      Variation

These are the very small changes in the member of the species (It is the group of organisms which have similar Morphology [outer appearance] and Anatomy [internally appearance] in the appearance. This occurs due to the reshuffling of genes on the Chromosome and due to slight and sudden change in the DNA sequence (Known as Mutation).

9.      Struggle for existence.

There is always a competition amongst the member of the same species, amongst the member of different species and with the environment. This is for the food, shelter, reproduction and survival.

10.  Adaptations.

There are variations (changes) which help the organism to modify themselves according to the changes in the environment.

11.  Evolution.

It is the slow and continuous process of change which results in the formation of the new species from the pre-existing ones or transformation of existing species into the new one. This occurs due to the accumulation (collection) of large number of the variations.

12.  Reproduction.

Life comes from the pre-existing life which means the living organisms can produce or give birth to young ones. Reproduction is the process of producing or giving birth to the young ones who look alike their parents.

13.  Growth

It is increase in the size of the individual. The growth of the individual is of two types.

INTUSSUSCEPTION. This type of growth is due to the internal addition of protoplasmic material by which cell enlarges and divides.

ACCRETION. Non-living object may also increase in size but it occurs due to deposition of similar material over the surface and this is called accretion.

 Two type of substance are responsible for the growth.

Protoplasmic substances are constituents of the living matter. They bring about increase in bulk of protoplasm.

Apoplasmic substances are non-living substances. E.g. cell wall, matrix, etc.

14.  Death. After a period of time each organism has to dies. It occurs naturally due to wear and tear.

15.  Life cycle. Each organism passes through the phase of life like birth, growth, maturation, reproduction, ageing and ultimately death. This is known as life cycle. Each phase in the life cycle has a specific time period in different organisms.

16.  Self regulation. There is an internal system of controls that operates in each living organism. It helps in regulation of body functioning including metabolism, growth, development, excretion and reproduction.

17.  Movements. It is of two type

·         Movement of the body parts e.g. opening and closing of stomata, moving the arms, etc.

·         Locomotion- moving from one place to another.

Ø  Autonomic (self) movements. This movement occurs due to purely internal forces. E.g. moving of organism by own wish, etc.

Ø  Paratonic (Induced) movements. This type of movement occurs due to external forces. E.g.  In summer season the animal find shady and moist place for rest.

18.  Coordination. Different parts of the body of an organism cooperate with one another for the functioning of the whole. This means if we like to do some work our body part involved in that work co-operates in one direction to do or complete that work.

19.  Metabolism. It is the sum total of all reactions in the cells of the organisms body. It is also known as the Biological reaction. It is of two type

·         Catabolism (destructive metabolism).  The breakdown reactions.

·         Anabolism (Constructive metabolism). The synthesizing or formation reactions.

20.  Excretion. Metabolism produces a numbers of by-products (extra or secondary product of the reaction) which are useless in the body. The harmful, excess of material and byproducts are expelled out from the body this known as excretion.

21.  Consciousness and Irritability.

Consciousness means knowing the one’s surrounding environment, actions and intentions. It is present only in the living organisms. Therefore consciousness is the defining property of living organisms.

Animals also posses self consciousness (awareness of self), Because they have sense organs for scanning the environment.

Irritability (sensitivity) is the process of responding (performing action) to a Stimulus (Disturbance). It is the property of the protoplasm and is shown by all organisms (plants and animals).

22.  Healing. Organisms have special property by which it can cover or regain the wound or injury on the body. It is body’s defence system which helps in the healing.

23.  Regenration. It is the ability of the organism to form or regain the lost or cut off part of the body. It is limited to certain organisms and in higher organisms to some organ of the body.

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