Level 1 + all of Level 2 

I can explain that cell structures and organelles interact as a system to maintain homeostasis 

Example: I can tell someone how the Golgi apparatus and ribosomes work together to maintain homeostasis

Level 1 + Level 2 + all of  Level 3

I can construct a written explanation (short paragraph) of how cell structures and organelles (i.e., nucleus, cytoplasm, cell membrane, cell wall, chloroplasts, lysosome, Golgi, endoplasmic reticulum, vacuoles, ribosomes, mitochondria) interact as a system to maintain homeostasis 

Example: How to the cell wall and vacuole help maintain homeostasis in a plant cell

Level 1 + Level 2 + Level 3  + all of Level 4

I can develop a refined written explanation (long paragraph) of how cell structures and organelles (i.e., nucleus, cytoplasm, cell membrane, cell wall, chloroplasts, lysosome, Golgi, endoplasmic reticulum, vacuoles, ribosomes, mitochondria) interact as a system to maintain homeostasis