NCERT 9TH CLASS SCIENCE CHAPTER TISSUE

 


INTRODUCTION

  •     In unicellular organisms a single cell performs all the vital  
  •     activities for example, digestion, respiration, excretion 
  •     etc.                                             
  •     In case of multicellular organisms specialized functions are performed by a different groups of cells
  •    possessing a well-developed division of labour to provide highest possible efficiency of particular function.
  •    As blood flows for transportation of O2, CO2, food, hormones & waste material, muscle cells are involved
  •    in movement etc so cells make  a group called tissue.                        
  •     A tissue is defined as a group of cells with similar structure, organized to do a common function.
  •     Term tissue was coined by Bichat.                     
  •    Branch of biology which deals with the study of tissue is called Histology.
  •     In plants and animals tissues are found but these tissues have differences on various aspects which are following.

PLANT TISSUE

    Plant tissues are of two types on the basis of their dividing capacity :-
1.     Meristematic tissue (growing tissue)
2.     Permanent tissue

    

1.    MERISTEMATIC TISSUE