What is the basic unit of life in all living organisms?

The correct answer is the cell, which is universally recognized as the basic unit of life in all living organisms. Cells serve as the fundamental building blocks from which all living things are constructed. Every living organism is made up of one or more cells, and these cells perform essential functions necessary for survival such as metabolism, growth, and response to stimuli.

Cells can be classified into two main types: prokaryotic and eukaryotic. Prokaryotic cells, such as bacteria, are simpler and do not have a nucleus, while eukaryotic cells, found in plants, animals, and fungi, have a defined nucleus and are more complex. Regardless of their classification, cells share common characteristics that make them the smallest living entities capable of replicating independently.

While tissues, organs, and organisms are all important biological structures, they are composed of multiple cells and rely on the functions of those cells to function properly. Tissues are groups of similar cells working together, organs are composed of different tissues, and an organism is the complete living entity made up of various systems and structures. Thus, the cell is the foundational unit from which the complexity of life arises.