Science / Biology

                 Science


Question : What is science ?

Answer :  science is the systematic study of structure and behaviour of natural and physical.


Science follows 4 main steps


    OBSERVATIONS


                         IDENTIFICATION


                                             EXPERIMENTS


                                                                 THEORY


Science is divided into three main parts

  • Biology

  • Physics

  • Chemistry


   Biology


 Biology is divided into three main parts


  • ZOOLOGY : 

  • BOTANY : 

  • MICROBIOLOGY : 



                                BIOLOGY

                         CLASS - 9

         FUNDAMENTAL UNIT OF LIFE

                         PART - 4


    # TYPES OF CELL


      Cells are two types :


  • Prokaryotic cell


  • Eukaryotic cell


     # prokaryotic cell :


  • Cells which do not have a well defined nucleus are called prokaryotic cells.


  • The nuclear region in these cells is not bounded by a nuclear membrane. 


  • The membrane bound cytoplasmic organelles ( mitochondria, Golgi apparatus, endoplasmic reticulum etc. ) are also absent in prokaryotic cells.


  • The only organelles present in them are ribosomes.




                                    STRUCTURE OF BACTERIAL CELL


# EUKARYOTIC CELLS :


  • Eukaryotic cells are the cells which have a well defined nucleus.


  • It is surrounded by a nuclear membrane.


  • These cells contain membrane-bound cytoplasmic organelles.


#  Differences between prokaryotic cell and Eukaryotic cell


  • CYTOPLASM


  • The jelly-like, semi-fluid part of the protoplasm which occurs between the plasma membrane and the nuclear envelope is called cytoplasm.


      # Cytoplasm has two parts :


  • Cytosol


  • Cell organelles


     # CYTOSOL 


  • It is the fluid part of the cytoplasm.


  • It is viscous, nearly homogeneous and crystallo colloidal liquid that contains a number of substances such as water, ions, enzymes, vitamins, amino acids, carbohydrates, lipids, proteins etc.


      # Cell organelles


  • It is a submicroscopic structure which is embedded in the cytosol and specialized to perform specific cellular functions. 


   #   MULTIPLE CHOICE QUESTIONS 

                                                  


















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