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What is the smallest structural unit of an organism?

  1. Tissue

  2. Cells

  3. DNA

  4. Organ

The correct answer is: Cells

Cells are the smallest structural unit of an organism because they are responsible for carrying out all of the essential functions of life. Tissue and organs are made up of multiple cells, so they are not the smallest unit. DNA is also not the smallest unit as it is a molecule that makes up genes and chromosomes within the cell.