Answer:
Tissues of the organ system
Step-by-step explanation:
The term 'levels of organization' refer to the organization of whole body or a living organism from smallest to largest levels.
The organization from the small scale starts from the cells which are ultimate units of life and goes to the largest level of whole organism with its organ systems coordinating to sustain the survival of organism.
Talking about levels of the organ system only:
One level is organ system level:
Where different organs interact with each other and formulate the proper functioning of an organ system. For example: In digestive system different organs like stomach, pancreas, liver and oesophageous coordinate with each other to make possible the proper digestion process.
2:organ level
Below the organ system level, comes organ level where different organs like heart, kidneys and liver and properly formed and performing their individual roles. The survival of any organism depends on not only the proper coordination of organs but also the functioning of individual organs.
3:tissues of the organ system
Each organ and organ system is composed of specific tissues that are further made up of cells. Tissues can be of different kinds depending upon the type of organ such as skin is made up of skeletal tissues, heart is made up of cardiac tissues, nervous system is made up of neural tissues etc.
They serve basic role for the proper functioning of any organ and organ system.
Hope it help!