What are groups of similar cells called?

A membrane refers to a thin layer of tissue that lines or covers surfaces, separating different environments within an organism. While membranes are crucial for various bodily functions, they do not consist of groups of similar cells working collectively; instead, they are structures formed by various cell types that serve to compartmentalize biological systems.

A system is a collection of organs that work together to perform complex functions in the body, such as the digestive or circulatory systems. Systems are composed of multiple tissues and organs, making them broader organizational units rather than groups of similar cells.

An organ is a structure made up of two or more different types of tissues that work together to perform specific tasks. For example, the heart is an organ composed of muscle tissue, connective tissue, and epithelial tissue. While organs consist of tissues, they do not represent groups of similar cells but rather combinations of different ones.