Tissues Notes | GSEB SCIENCE HUB

Tissues 

Tissues are categorized as −
Plant Tissue
Animal Tissue

♦️Plant Tissue
Following are the major types of plant tissue −
➖Meristematic Tissues
➖Permanent Tissues

▪️Simple Permanent Tissues
➖Parenchyma
➖Collenchyma
➖Sclerenchyma
➖Epidermis

▪️Complex Permanent Tissue
➖Xylem
➖Phloem

▪️Meristematic Tissue
➖Meristematic tissue mainly consists of actively dividing cells, and helps in increasing the length and thickening the stems of the plant.

➖Meristematic tissue, commonly, present in the primary growth regions of a plant, for example, in the tips of stems or roots.

➖Depending on the region (where the meristematic tissues are found); meristematic tissues are classified as apical, lateral, and intercalary (see the image given below).

➖Apical meristem (as shown in the above image) is present at the growing tips of stems and roots and helps in their growth.

➖Lateral Meristem is found in stem or root region and helps in their growth.

➖Intercalary meristem is found at the base of the leaves or internodes (on twigs) and helps in growth.


🔸Permanent Tissue
Cells of meristematic tissue later differentiate to form different types of permanent tissue.

Permanent Tissue is further categorized as −
➖Simple Permanent Tissue and
➖Complex Permanent Tissue

🔸Simple Permanent Tissue
Simple Permanent Tissue further categorized as −
➖Parenchyma
➖Collenchyma
➖Sclerenchyma
➖Epidermis

🔸Parenchyma tissue provides support to plants and also stores food.
🔸Sometimes, parenchyma tissue contains chlorophyll and performs photosynthesis, in such a condition, it is known as collenchyma.
🔸The collenchyma tissue provides flexibility to plant and also provides mechanical support (to plant).
🔸The large air cavities, which are present in parenchyma of aquatic plants, give buoyancy to the plants and also help them float, are known as aerenchyma.
🔸The Sclerenchyma tissue makes the plant hard and stiff. For example, the husk of a coconut is made up of sclerenchymatous tissue.
🔸The cells of Sclerenchyma tissue normally are dead.
🔸The outermost layer of cells is known as epidermis.
🔸The epidermis is usually made up of a single layer of cells.
🔸The entire surface of a plant has the outer covering of epidermis, which protects all the parts of the plant.


🔷Complex Permanent Tissue
The complex tissue, normally, consists of more than one type of cells which work together as a unit.

Complex tissues help in the transportation by carrying organic material, water, and minerals up and down in the plants.

🔸Complex Permanent Tissue is categorized as;
➖Xylem
➖Phloem

🔸Xylem, normally, consists of tracheid, vessels, xylem parenchyma, and xylem fibers.

🔸Xylem is accountable for the conduction of water and mineral ions/salt.

🔸Phloem, normally, is made up of four types of elements namely −
➖Sieve tubes
➖Companion cells
➖Phloem fibers and
➖Phloem parenchyma

🔸Phloem tissue transports food from leaves to other parts of the plant.