The ranking of the given items from largest to smallest is as follows:
Organism > Cell > Nucleus > Chromosome > Gene > DNA
DNA is a molecule that can be thought of as the blueprint of life. In other words, it acts as a template which is replicated before cell division. It provides the information for building all the proteins within every living thing.
Gene is the basic functional and physical unit of heredity and is made up of DNA. Genes determine the traits and functions of a cell and are transferred from parent to daughter cells.
Chromosomes contain nucleic acids and proteins and they carry the genetic information in the form of genes.
The nucleus contains chromosomes. It is a membrane-bound structure and contains the hereditary information.
A cell is the smallest functional unit of life and contains nucleus and cytoplasm in a membrane-bound structure.
An organism is made up of a number of cells.
Hope this helps.