Question

Do you agree that “A cell is the building unit of an organism”. If yes, explain why?

Answer 1

Yes.
An organism is made up of various organ systems like digestive system, nervous system, etc. These organ systems in turn are made up of various organs which are made up of tissues. Also tissues are a group of cells performing the same function. Hence, a cell is the building unit of an organism. Cell → tissue → organ → organ system → organism.