Revision: Tissue >> Plant Tissues Biology ICSE ICSE Class 7 CISCE

A group of similar cells, along with intercellular substances which perform a specific function, is called a tissue.

• Cells that perform a particular function always live in a group. This group of cells is called a tissue.
• For example, blood, phloem, muscle, etc. are examples of tissues.

A group of similar cells which perform a specific function.
example: Muscular tissue in animals.

A tissue is a group of cells that are similar in structure and are organized together to perform a specific task.

The tissue is a group of cells of similar structure and function.

Vascular tissue is the complex plant tissue in higher plants that are composed of xylem and phloem and is concerned with conducting water, minerals, and organic food throughout the plant body.

A tissue, in biology, is defined as a group of cells that have a similar structure and perform a specific function. The word tissue originates from French, which means "to weave."

Meristematic tissue is a group of cells that constantly divide and produce cells indefinitely throughout the life of the plant.

Permanent tissue refers to a group of cells which temporarily or permanently cease to divide and thus assume permanent form and function

• Anatomy = Study of Internal Structure - Plant anatomy is the study of the internal structure of plants, which includes the organisation and structure of tissues.
• Basic Unit = Cell - The basic unit of plants is the cell. Cells are organised into Tissues → Organs (organisational hierarchy).
• Tissue Definition - A tissue is a group of similar cells having a common origin that perform a specific function together.
• Monocots vs. Dicots - Anatomical (internal structural) differences exist between monocots and dicots, so it's important to know them separately.
• Internal Structure Adapts - The internal structures of plants adapt according to their environment (e.g., water availability, climate), and structural similarities exist in both external and internal morphology of organisms.

• Meristematic tissue consists of cells that can divide and is restricted to specialised regions of the plant.
• Apical meristem is found at the root and shoot tips, is a primary meristem and increases the length of the plant.
• Intercalary meristem is found between mature tissues, is a primary meristem and helps form branches and flowers.
• Lateral meristem is found in mature regions, is a secondary meristem and is responsible for secondary growth (e.g. vascular cambium, cork cambium).
• Axillary bud is present in the axils of leaves and is responsible for forming branches or flowers.

• Parenchyma has thin-walled cells with intercellular spaces; the cell wall is made of cellulose. It performs photosynthesis, storage and secretion.
• Collenchyma is made of living, closely packed cells that are thickened at corners due to the deposition of cellulose and pectin. It provides mechanical support to young stems and petioles.
• Sclerenchyma is made of dead cells with thick, lignified walls and has two types of cells: fibres and sclereids.

Xylem

• Xylem consists of tracheids, vessels, xylem fibres and xylem parenchyma. It conducts water and minerals from roots to other parts of the plant.
• In stems (endarch), protoxylem is towards the centre and metaxylem towards the periphery. In roots (exarch), protoxylem is towards the periphery and metaxylem towards the centre.

Phloem

• Phloem consists of sieve tube elements, companion cells, phloem fibres and phloem parenchyma. It transports food from leaves to various parts of the plant.
• Mature sieve tube elements lack a nucleus, so their functions are controlled by the nucleus of companion cells.
• Protophloem has narrow sieve tubes (first formed), and metaphloem has bigger sieve tubes (later formed).