The Living World – Notes

Characteristics of living organisms
Living organisms display certain characteristics.
Growth and reproduction are the non-definitive characteristics of living organisms.
Metabolism and cellular organisation are considered to be the definitive characteristics of living organisms.
Living organisms, whether unicellular or multi-cellular, grow due to cell division.
Both unicellular and multi-cellular organisms reproduce.
Reproduction, however, is not a definitive criterion for distinguishing the living, because some organisms like mules and sterile worker cannot produce offspring.
All living organisms sense and respond to environmental stimuli such as light, water and temperature.
Consciousness is therefore, another definitive characteristic of living beings.

Classification of Living Organisms
The earth abounds with millions of different types of fungi, plants, microorganisms and animals.