An aggregation of cells and extracellular materials which perform a discrete function is known as

Answer: Tissue

Explanation:

The basic structural and functional unit of life is cell. It is the smallest functional unit inside the body.

A number of cells aggregate together to form tissues that function together is known as tissues.

It lies at the second level when it comes to level of organization in a living organism.

A group of tissue work together to make the organ functional. Example: The adipocytes are the cells that combine to form adipose tissue.