The Living World - Living & It's Characteristics

Description:

The objects exhibiting growth, development, responsiveness, adaptation and other characteristics of life are designated as living beings.

Characteristics of living organisms −

Growth

• Irreversible increase in mass of an individual.
• In plants, growth occurs throughout their life while in animals growth occurs until a limited period.
• Growth can happen in two ways: internal (intussuspection e.g. human beings) and external (accretion e.g. mountains).
• Not a defining characteristic of living organism.

Reproduction

• Formation of new individuals from existing ones.
• Two modes: asexual (uniparental) and sexual (biparental, involves fusion of gametes).
• Organisms like mules, worker bees, infertile human couples cannot reproduce hence it is not a defining property for living organisms.

Metabolism

• Sum total of all chemical reactions occurring inside the organism.
• Cell free reactions are neither living nor non-living.
• Metabolism is defining property of living beings.
• Two types of reactions: Anabolic (building up reactions) and catabolic (breakdown reactions).

Consciousness

• It is the awareness of the surrounding and response to external stimuli which is a defining characteristic of living beings only.