cells

• what is cell?

  The cell is the fundamental structural and functional unit of all living beings.
• how many days does it take for an RBC to die?

  about 120
• who constructed the simple microscope?

  Antony Van Leeuwenhoek
• which lens was used to construct the simple microscope?

  biconvex lens
• who constructed the compound microscope?

  Robert Hooke
• how many lenses were used to construct the compound microscope?

  2
• which type of mirror was used to construct the compound microscope?

  Concave mirror
• what magnification is given by the electron microscope?

  200,000 time
• magnification given by compound microscope

  2,000 time
• State the cell theory.

  i. The cell is the smallest unit of structure of all living things.

  ii. The cell is the unit of function of all living things.

  iii. All cells arise from pre-existing cells.
• Rudolf Virchow added to the cell theory that all the cells arise from pre-existing cells
• The cell theory was proposed in which year?

  1839
• The bigger an organism is the greater the number of cells in its body
• example of single celled organisms

  Bacteria, yeast and amoeba
• example of few celled organisms

  Spirogyra and volvox
• example of multi celled organisms

  Human beings and Mango tree
• Which is the smallest cell in the Human body?

  Red blood cell
• example of the longest cell

  Nerve cell
• example of the smallest cell

  Bacteria and Red blood cells
• example of the largest cell

  birds egg - ostrich egg
• Cells generally remain small in size. Give reason.

  different regions of silk and communicate with each other rapidly for the cell to function effectively. cells have a large surface area or volume ratio for Greater diffusion of substances in and out of the cell
• what are the different shapes of cell?

  dislike polygonal rectangular cuboid thread like branched or even irregular
• human blood cells are circular and biconcave give reason.

  to pass through narrow capillaries and transport oxygen
• white blood cells are amoeboid. give reason

  squeeze through blood capillary wall
• muscle cells are long and contractile

  to pull or squeeze the parts
• why are guard cells of stomata Bean shaped

  to open and close the pores
• what are the parts of a generalised cell?

  cell membrane or plasma membrane, nucleus and cytoplasm
• cell organelles are living parts
• cell membrane is composed of lipoproteins.
• cell membrane is selectively permeable
• the cell wall is made of cellulose a non living substance
• cell wall is freely permeable
• cytoplasm is a semi liquid substance
• Organisms start like a single cell called ' Zygote '
• How many microscopes were invented the Antony Van Leewenhoek?

  400
• What is the magnifying power of simple microscope?

  up to 200 times
• Electron microscope uses beam of electrons which are bent by magnets.
• What did Matthias Schleiden state in the cell theory?

  Plants are made up of cells and cells perform various like processes.
• What did Theodor Schwann State in the cell theory?

  All animals and plants are composed of cells which serve as the units of structure and function.
• Rbcs die in about 120 days.