The level of organization where a group of similar cells perform the same function is called a tissue.

Here's a breakdown of the levels of organization in biology:

1. Cells: The basic unit of life.

2. Tissues: A group of similar cells working together to perform a specific function (e.g., muscle tissue, nervous tissue).

3. Organs: Structures made up of different tissues working together to perform a more complex function (e.g., heart, stomach, brain).

4. Organ Systems: A group of organs that work together to carry out major bodily functions (e.g., digestive system, circulatory system).

5. Organism: A complete living being made up of multiple organ systems working together.