Page 15 - Biology_F5
P. 15

Biology for Advanced Level Secondary Schools

          Golgi vesicles. These are responsible for  controls all cell activities such as growth,
          storage and transportation of secretions of  cell  division,  DNA replication  and its
          the cells. In addition, the plant cell has a  transcription  to  RNA. It also contains
          large central vacuole which is responsible  hereditary material, which transmits traits
          for storage of nutrients and water.  The  from parents to the offspring.
          nucleus is a vital part of the cell, as it
          FOR ONLINE READING ONLY



                            Cell wall      Plasmodesma   Middle lamella   Cell walls of adjacent
                                                                          cells
                         Nuclear pole
                     Nuclear envelope                                     Free ribosomes scattered
                                                                          through cytoplasm
                     (two membranes)
            Nucleus        Nucleolus                                        Rough endoplasmic
                                                                            reticulum
             Chromatin  Heterochromatin                                      Chloroplast
                          Euchromatin                                          Chloroplast envelope
                   Smooth endoplasmic                                          (two memberane)
                            reticulum                                              Granum
                Cell surface membrane
                                                                                   Mitochondrion
                          Cytoplasm
                                                                                  Golgi vesicle
                                                                                  Golgi apparatus
                  Microtubule – often near                                        Cell sap
                       to cell periphery                                         Tonoplast  Vacuole








                       Figure 1.4: A generalised structure of a plant cell as seen under electron microscope


           Activity 1.1: Observation of a plant       (b) Using forceps, remove the thin
           cell under a light microscope                 transparent inner lining.

           Materials                                  (c) Put a specimen on a watch glass or
           Onion bulb, a  light  microscope,             petri dish containing some water to
           microscope slide, slide cover, petri dish     prevent shrinking.
           or watch glass, iodine solution, water,    (d) Mount the specimen at the centre of
           forceps, a needle, and a knife or surgical    the microscope slide.
           blade or scalpel.                          (e) Add a drop of iodine solution.

           Procedure                                  (f)  Using  a needle,  place the  cover slip
           (a) Slice the onion longitudinally into       gently.  Make sure  there  are  no  air
               small  parts by using a knife or          bubbles under the cover slip.
               scalpel.


                                                                      Form Five Student’s Book
             8
   10   11   12   13   14   15   16   17   18   19   20