Each and every organism can live only for a certain period of time.
The period from birth to the natural death of an organism represents its life span.
Whatever be the life span, death of every individual organism is a certainty, i.e., no individual is immortal, except single-celled organisms.
The life spans of organisms are not necessarily correlated with their sizes; the size of crows and parrots are not very different yet their life spans show a wide difference.
Similarly, a mango tree has a much shorter life span as compared to a peepal tree.
The life cycle of an organism usually includes four stages:
Juvenility
Maturity
Ageing
Death
Reproduction is defined as a biological process in which an organism gives rise to young ones (offspring) similar to itself.
The offspring grow, mature and in turn produce new offspring.
Thus, there is a cycle of birth, growth and death.
Reproduction enables the continuity of the species, generation after generation.