Answer:
Organism.
Explanation:
The cell is the smallest form of life. Cells work together to form tissues, tissues work together to form organs, and organs work together to create an organ system, and organ systems work together to create organisms. I believe "organism" includes all of these other levels.
Research has demonstrated that neural stem cells have an impaired ability to differentiate into functional neurons when subjected to ethanol. They found out that treating cultured neural system impairs their ability to differentiate in functioning neurons. With this impairment it seems to be united with aberrant, dense methylation and loci which are active in normal tissue.
