Question

Whatever be the lifespan, the death of every individual organism is a certainty, i.e, no individual is immortal, except single –celled organisms. Explain.

Answer 1

Hint: cells function differently in single –celled and multicellular organisms. A single celled organism depends upon just one cell for all of its functions while a multicellular organism has specialized cells to perform different functions. There are many types of single –celled organisms in the world including protists, amoeba, bacteria, algae etc.

Complete answer:
To answer this question you must know about
A unicellular organisms, also known as single –celled organism consists a single cell such as protozoa, algae, fungi, bacteria etc. and performed asexual reproduction which include binary fission, fragmentation, multiple fission, budding etc.
In unicellular organisms cell division takes place at any plane at organelle level And a single cell performs the necessary function of life processes. A life span of single –celled organisms is usually short. Injury to the cell leads to the death of the cell but, the most important, it never dies because this organism has the ability to regenerate itself so it is immortal (unlimited growth).
Multicellular organisms consist of more than one cell. They performed sexual reproduction in which gametes form by mating two individuals. The lifespan of multicellular organisms is long as compared to unicellular ones. After injury cells get damaged their body heals those injuries but they don’t have the ability to themselves like single –celled organisms. So multicellular organisms are mortal (limited growth).
Since single celled organisms have the ability to regenerate themselves whereas multicellular organisms cannot, therefore no individual is immortal, except single celled organisms.

Note:-
Unicellular organisms fulfill their nutritional requirement by a process called phagocytosis. In which they engulf food using plasma membranes. These organisms are typically resistant to extreme conditions such as pH or temperature. They are being utilized medically, for instance,in formulating antibiotics.