What is the basic unit of life and the building block of tissues and organs?

Atoms are the smallest units of matter that retain the properties of an element, but they are not considered living units. While atoms combine to form molecules, which in turn make up cells, they do not themselves perform biological functions or compose tissues and organs.

Organelles are specialized structures within a cell that perform specific functions, such as energy production or protein synthesis. While they are essential for cellular function, they are not the basic unit of life, as they cannot exist independently and are part of the larger cellular structure.

DNA, or deoxyribonucleic acid, is the hereditary material in living organisms that contains the genetic instructions necessary for development and functioning. Although DNA is crucial for the transmission of genetic information, it is not a living unit or building block of tissues; rather, it resides within cells and contributes to their function.