Tissues are groups of similar cells that work together to perform specific functions in an organism. They serve as the structural and functional units that form organs, playing critical roles in various biological processes. Permanent tissues may be defined as a group of living or dead cells formed by meristematic tissue and have lost their ability to divide and have permanently placed at fixed positions in the plant body. A tissue, in biology, is defined as a group of cells that possess a similar structure and perform a specific function. The word tissue originates from French, which means “to weave.” Tissues Types In animals, there are 4 types of tissues, namely: Muscle tissue (cardiac, skeletal and smooth muscle tissues) Connective tissue (cartilage, blood ... Learn the definition of tissue in biology, the types of plant and animal tissues, and their functions.