Which of the following is a tissue?

Concept

A tissue is a group of similar cells and their extracellular material that work together to perform a function. An organ is a larger functional unit made of multiple tissue types.

Application

Blood contains formed cellular elements suspended in plasma, a fluid extracellular matrix. Therefore, blood is classified as a specialized connective tissue.

Contrast

• A lung contains several tissue types arranged together, so it is an organ rather than a single tissue.

• An ovary contains multiple tissues that jointly perform reproductive functions, so it is an organ.

• A kidney contains epithelial, connective, vascular and nervous tissues organized for filtration and regulation, so it is an organ.

Cross-check

The classification is consistent with the biological hierarchy: tissues combine to form organs. Thus lung, ovary and kidney are organs, whereas blood itself is a tissue.

Blood is the required tissue.