These could be arranged from smaller to the biggest by taking gene as the smallest unit as it stores heridity information which differs in every being basically it is a part of dna .

And when these dna are packed around histone protein in a cylindrical manner they form thread like structures called cromosomes.

These cromosomes could be found in the nucleolus during cell division along with nucleo plasm and nuclear membrane in the nucleus.

Nucleus is the centeral part of all the data processing in a cell or we can say that it decides what is good for cell to intake or to excreate it performs as a brain for the cell.

Cell is often termed as the basic structural and functional unit of life.which performs specific functions in accordance to the specific spot which they have got for ex.photosynthetic cells are present in the leaf of a plant to perform a specific function called photosynthesis.

When a group of similar cells are arranged so as to perform a specific function are often called tissue.tissues are basically of four types epithilial,muscular,connective,nervous in animals and are of two types in plants:meristamatic and permanent.

When similar tissues are grouped together to perform a similar function they are called organs for ex-cardiac muscular tissue together form an organ called heart.

When a group of organs are arranged to perform a specific function they together constitute a system called organ system for ex- kidneys, urinary bladder and urethara together constitute a system called excreatory system.

When these systems are present in a systematic way in a body then that body is called an organism.so it could be arranged as gene-cromosome-nucleus-cell-tissue-organ-system-organism.