The main characteristics of living organisms are:
(a) Definite shape and size: They have a definite shape and size that change as the organism grows.
(b) Growth and development: They show growth and development.
(c) Reproduction: They give birth to young ones by reproduction.
(d) Consciousness: They have an inherent capability to sense their surroundings or environment and respond to these environmental stimuli.
(e) Death: It is a permanent feature of all living organisms.