Biology · Structural Organisation in Animals · NEET
It is more than only cells. NCERT defines a tissue as a group of similar cells ALONG WITH intercellular substances that perform one or more functions. The intercellular substance (the material between cells) is part of the tissue. This is why blood, where the cells float in a fluid matrix (plasma), still counts as a tissue. NEET often traps students who forget the 'intercellular substance' part of the definition.
A tissue is one level below an organ. A tissue = similar cells + intercellular substance doing one function. An organ = two or more tissue types arranged together to do a bigger function. For example, the heart is an organ made of all four tissue types (epithelial, connective, muscular and neural). So: cell to tissue to organ to organ system.
In a unicellular organism, one single cell performs all functions like digestion, respiration and reproduction, so there is no need to group cells. In multicellular animals, the same functions are split among different groups of cells. A group of similar cells doing one shared job is a tissue, so tissues only exist in multicellular animals.
Exactly four: epithelial, connective, muscular and neural. NCERT states that all complex animals consist of only these four basic tissue types. These four are then arranged in specific proportion and pattern to build organs like the stomach, lung, heart and kidney. Remembering this number 'four' is a common one-mark point in NEET.
Intercellular substance is the non-living material that lies between the cells of a tissue, also called the matrix in connective tissue. It can be jelly-like, fluid (like blood plasma) or solid (like bone matrix). It holds cells together and helps them work as a unit. Because the definition includes this substance, tissues are not only about cells.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
NCERT defines a tissue as a group of cells along with intercellular substances performing one or more functions in the body. In multicellular animals, these are similar cells working together for a specific function.
The heart contains all four basic tissues: epithelial, connective, muscular and neural. NCERT uses the heart as the classic example, so it is a frequent NEET recall point.
Yes. Blood is a connective tissue because its cells (RBCs, WBCs, platelets) are suspended in an intercellular fluid matrix called plasma, which fits the definition of a tissue that includes intercellular substance.
After tissue comes the organ, then the organ system. The order is cell to tissue to organ to organ system, each level built from the one before it for better division of labour.
Structural Organisation in Animals is a scoring Class 11 chapter. The tissue definition and the 'four basic types' are direct one-mark questions, and they form the base for epithelial, connective, muscular and neural tissue questions that appear every year.
