➤ Tissue is a group of cells that work together to perform a specific function.
➤ Cells in a tissue usually have similar structure and origin.
➤ Example: Plant tissues and animal tissues.

➤ Tissues help in division of labour in multicellular organisms.
➤ Different tissues perform different functions.
➤ This makes biological processes more efficient.

➤ Plant tissues are broadly divided into two types.
➤ Meristematic tissue → actively dividing cells.
➤ Permanent tissue → mature cells that have lost the ability to divide.

➤ Meristematic tissues consist of actively dividing cells.
➤ They are responsible for plant growth.
➤ These tissues occur in growing regions of plants.

➤ Meristematic tissues occur in growing regions of plants.
➤ Example: root tips and shoot tips.
➤ These regions help in increase in plant size.

➤ Meristematic cells are small and actively dividing.
➤ They contain dense cytoplasm and large nucleus.
➤ Vacuoles and intercellular spaces are absent.

➤ Meristematic cells do not have intercellular spaces.
➤ They are compactly arranged.
➤ This allows efficient cell division.

➤ The cell wall of meristematic cells is mainly composed of cellulose.
➤ Cellulose provides strength and flexibility.
➤ It is a common component of plant cell walls.

➤ Apical meristem is present at the tips of roots and shoots.
➤ It causes primary growth of plants.
➤ Primary growth leads to increase in plant length.

➤ Lateral meristem occurs beneath the bark of stems and roots.
➤ It is responsible for secondary growth.
➤ Secondary growth causes increase in thickness (girth) of plants.

➤ Intercalary meristem occurs at nodes or internodes of plants.
➤ It helps in elongation of stems and leaves.
➤ It is commonly found in grasses and bamboo.

➤ Lateral meristem is responsible for secondary growth.
➤ It increases the thickness (girth) of stems and roots.
➤ Example: Cambium.

➤ Cambium is a type of lateral meristem.
➤ It helps in secondary growth of plants.
➤ It produces secondary xylem and secondary phloem.

➤ Permanent tissues develop from meristematic tissues.
➤ These cells lose the ability to divide.
➤ They become specialized to perform specific functions.

➤ Cells of permanent tissue are differentiated.
➤ They perform specific functions such as storage, protection, and support.
➤ They usually do not divide further.

➤ Simple permanent tissues contain only one type of cells.
➤ These cells have similar structure and function.
➤ Examples: Parenchyma, Collenchyma, Sclerenchyma.

➤ Parenchyma is the most common plant tissue.
➤ It mainly helps in storage of food and water.
➤ These cells are living with thin cell walls.

➤ Parenchyma cells are living cells.
➤ They have thin cellulose cell walls.
➤ Intercellular spaces are usually present.

➤ Chlorenchyma is a type of parenchyma containing chlorophyll.
➤ It helps in photosynthesis.
➤ It is commonly found in green parts of plants.

➤ Aerenchyma is a modified form of parenchyma.
➤ It contains large air spaces.
➤ It helps aquatic plants in floating and gas exchange.

➤ Collenchyma provides mechanical support to plants.
➤ It also provides flexibility, allowing plant parts to bend without breaking.
➤ It is commonly found in leaf stalks and young stems.

➤ Collenchyma cells are living cells.
➤ Their cell walls are unevenly thickened at the corners.
➤ The thickening is due to cellulose and pectin.

➤ Sclerenchyma cells are dead at maturity.
➤ They have very thick cell walls.
➤ Their walls contain lignin, which provides rigidity.

➤ Lignin is a complex organic substance found in cell walls of sclerenchyma.
➤ It makes the cell walls thick and rigid.
➤ It provides mechanical strength to plants.

➤ Complex tissues contain more than one type of cells.
➤ These cells work together to perform common functions.
➤ Examples: Xylem and Phloem.