CBSE /BSEB CLASS IXTH BIOLOGY

 TYPES OF CELLS ➡️There are two types of cells      (on the basis of structural form )  I) Prokaryotic Cells  II) Eukaryotic Cells  I) Prokaryotic cells   ➡️It is primitive(साधारण) and incomplete cells.  ➡️It is small in size (1 - 10mm).  ➡️Nucleus is absent.  ➡️Nuclear region or nucleiod is not surrounded by a nuclear membrane.  ➡️It has single chromosome*.  ➡️Nucleolus* is absent.  ➡️Membrane bound cell organelles are absent.  ➡️Cell division takes place by fission or budding (no mitosis).  ➡️It consists of a single membrane -      a. The plasma membrane or          Cell membrane  ➡️It is Unicellular organisms.  ➡️DNA* is not associated (रिश्तेदार/जुड़ा हुआ ) with protein.  Note point :- ➡️*Nucleoid - The undefined nuclear region in cytoplasm is called nucleoid(). ➡️DNA- Deoxyribonucleic acid  ➡️A polymeric nucleic acid.  ➡️RNA - Ribonucleic acid ; polymeric nucleic acid.  Fig. No-1                    II) Eukaryotic Cells   ➡️Eukaryotic (Eu= good or well ;karyon=nucleus)  ➡️It is lar

 There are two types of organisms - 1. Unicellular organisms  2. Multicellular organisms  Q. Write the difference between Unicellular and multicellular organisms.  Ans- 1.) Unicellular organisms :- ➡️It is made of only one cell. ➡️All activities of the organisms are performed by a single cell.  ➡️Reproduction consumes() a single cell. ➡️Its life is short. 2.) Multicellular organisms :- ➡️It is made of large number of cells.  ➡️A single cell performed one or few activities of the organisms.  ➡️It has lots of organs.  ➡️We can see easily.  ➡️Its life is long.  Organisms Types of cell पढ़ने के लिए नीचे क्लिक करें  👇 Type of cells

 What is microscope? Ans- Microscope is a high resolution instrument. Which is used for observing the fine details of very minute (बहुत छोटे) objects.  Types of of Microscope -  There are two types of microscope.  I) Light microscope  Ii) Electronic microscope  I) Light or compound microscope :- ➡️It is a simple microscope which is used in school.  ➡️It uses glass lenses.  ➡️It uses a beam of light to illuminate the object.  ➡️In this microscope internal vacuum is not required.  PARTS OF COMPOUND MICROSCOPE  i) eye piece  ii) draw tube iii) body tube iv) coarse adjustment  v) fine adjustment  vi) arm (limb)  vii) clip viii) inclination joint(swivel)  ix) pillar x) base xi) condenser adjustment  xii) foot xiii) revolving nose piece  xiv) objectives  xv) slide xvi) stage xvii) condenser  xviii) diaphragm  xix) reflector  2. Electronics microscope  🔬 ➡️It is developed by Knoll and Ruska (Germany) in 1932. ➡️It uses electromagnets.  ➡️It uses a beam of electrons instead of light.  ➡️Inte

What is cell? Ans-It is the basic structural and functional unit of life. ➡️Its shape is like a honeycomb.  ➡️It is hexagonal structure.  ➡️It is discovered by Robert Hooke in 1665. ➡️Firstly Robert Hooke saw in a thin slice of cork*. ➡️Cells means in latin "little room." Note:- *Cork - Cork is a substance which is obtained from the bark(वृक्ष की छाल) of a tree. Cell Theory  ➡️Cell comes from the latin word 'Cellula' which means "a little room". ➡️It is discovered by English scientist, Robert Hooke (1635- 1703). ➡️His book 'Micropraphia' was published in 1665.  ➡️In 1674, Anton von Leeuwenboke(1632 - 1723) is discovered free living cells in pond water for the first time in 1674. ➡️He also discovered sperm and identified the sperm cells of humans, dogs, rabbits, frogs, fish and insects.  ➡️Nucleus (in plant) is discovered by Robert Brown (1787- 1889) in 1831. ➡️He is a Scottish botanist.  ➡️The term Protoplasm* is given by J. E Purkinje(1787 - 1869) i