• williams sodic Definition of Cell
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    Cell can be defined as the structural and functional unit of a living organism. It is the simplest, the smallest and basic unit of life. All living things (plants and animals) are made up of cells. The cell is regarded as the basic unit of all living things because it can carry out all life activities such as feeding, reproduction, excretion, growth, adaptation, respiration, definite life span, sensitivity and movement. --- Organisms can be classified based on the number of cells they have -------- i) UNICELLULAR or ACELLULAR ORGANISMS: They consists of only one cell (eg: Amoeba, Euglena, Paramecium, Chlamydomonas etc.) ------------- ii) MULTICELLULAR ORGANISMS: They consists of two or more cells (eg: fish, Hydra, Spirogyra, Flowering plants, birds, man). ------------ THE CELL THEORY: Celll theory states that --- i) The cell is the structural and functional unit of life. ------ ii) All living organisms are made up of cells. ---- iii) All cells come from previously existing cells. ------ iv) There is no life apart from the life of cells. ------ v) All living things are either unicellular or multicellular.
    25 July 2010Comment
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    • enemuo nzube CELL STRUCTURE
      A typical living cell either plant cell or animal cell is made up of three(3) major parts. These are :
      a. Layers
      b.organelles
      c. fluids
      A. LAYERS
      Layers in living organism are as follows:
      1.CELLWALL
      -It is mostly found in plants
      -It is made up of cellulose, lignin, pectin, e.t.c
      functions
      a. It give protection to the cell from damage
      b. It helps to give definite shpe to the cell
      c. It helps to give rigidity to the cell
      2.CELL MEMBRANE
      -This can be found in both plants and animals
      -It is also called plasma-membrane
      It is made up of a bi-layer of lipo-proteins i.e lipids and proteins
      functions
      It is semi- permeable in nature, therefore, it is used for oesmosis
      3. MIDDLE LAMELLA
      -this is mostly found in plant cell
      -It help to join cells to cells

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