Question

In multicellular organisms, cells that do a specific job are often grouped together into masses or layers that are more complex systems. What ar these more complex systems called?

Answer 1

Tissues.

Step-by-step explanation:

In Multicellular organisms' cells that work together for a common focus are divided into different sects if you will, the basics of Organelles which group into Cells > Tissues which then combine into Organs > Organ Systems and then the Organism itself.