CBSE/NCERT/Notes/Class_09_Science
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Note on Tissues in Action
A tissue is a group of similar cells that work together to perform a specific function. In multicellular organisms, tissues allow for the division of labour, which increases the body's efficiency.
Plant tissues are broadly classified based on their ability to divide:
Consist of actively dividing cells with thin walls, dense cytoplasm, and large nuclei.
Formed when meristematic cells stop dividing and take on a permanent shape and function.
Unidirectional Flow Water transport in the xylem is almost always unidirectional—from the roots up to the leaves—driven primarily by transpiration pull.
Bidirectional Flow Unlike xylem, phloem transport is bidirectional, allowing the plant to move sugars from 'source' (leaves) to 'sink' (roots, fruits, growing buds).
Animal tissues are categorized into four main types:
Forms the outer covering and internal linings.
Connects and supports other tissues.
Responsible for all body movements.
Specialized for communication.
Limited Regrowth Most neurons in the human brain and spinal cord do not divide after birth. This means damage to nervous tissue is often permanent and very difficult for the body to repair.
The coordination of bones and muscles allows for movement and posture.
/CBSE/NCERT/Notes/Class_09_Science/Chapter_03_Tissues_in_Action.mdx