required practicles

• what can we use instead of a lamp on a microscope?

  a mirror , light reflects up through microscope slide
• what magnification are objective lense normally?

  4x, 10x or 40x
• what does the eyepeice have a magnification of?

  10x
• microscope rp

  1. place slide onto stage ( use clips to hold in place )
  2. select lowest power objective lens usually 4x
  3. position objective lens so it almost touches the microscope lens - slowly turn coarse focussing knob looking from the side
  4. stop turning when it almost touches slide
  5. look down through eyepeice and slowly turn the coarse focussing dial - increaces the distance between the objective lens and the slide - do this until cells come into focus
  6. mag of eyepeice x mag of objective lens - 10 x 4 = 40 x
  7. use a higher objective lens mag - adjust fine focussing dial to bring back into focus
• what organelle cant you see with a light microscope?

  ribosomes
• osmosis rp

  1. peel potato
  2. use a cork borer to produce three cylinders of potato. Using a cork borer makes all the cylinders the same diameter
  3. using a scalpe trim the cylinders to the same length
  4. measure the length of each cylinder using a ruler and the mass by using a ballance
  5. place each cylinder into a test tube and add 10cm3 of a 0.5 molar sugar solution to the first test tube
  6. add 10 cm3 of 0.25 molar sugar solution to the second test tube and 10cm3 of distilled water to the third
  7. leave overnight
  8. remove the potato cylinders and gently roll them on paper towel to remove any surface moisture
  9. measure the length and the mass of the cylinder again
  10. change / original x 100