Final answer:
The hierarchy of biological organization orders structures from least to most complex as follows: DNA, nucleosome, chromatin, chromosome. Organs are part of this hierarchy and are more complex than tissues but less complex than organ systems.
Step-by-step explanation:
Levels of Organization in Biology
In biology, understanding the levels of organization is fundamental to grasping how complex structures are built from simpler ones. Starting with the smallest unit, DNA is the molecule that contains the genetic blueprint of an organism. Multiple DNA molecules wrap around proteins called histones to form a nucleosome, which is the basic unit of chromosomal structure. When many nucleosomes coil together, they form a chromatin fiber, which further condenses to create a chromosome. This chromosome is a single piece of coiled DNA containing many genes. When comparing the given options, the correct sequence from least to most complex is: DNA, nucleosome, chromatin, chromosome.
As we continue with the hierarchy of biological organization, organs come after tissues and are themselves part of larger organ systems. In terms of complexity, the entire organism is at the top, followed by organ systems, and then individual organs.