Practicals

Cards (33)

  • Why is 70% alcohol used for disinfectant of covid-19
    It destroys the lipid bilayer and disrupts the hydrogen bonding of proteins/
  • What is wax soluble in
    Histoclear
  • What is DPX mountnt soluble in
    Histoclear
  • Is alcohol solbule in water
    No it is miscible
  • What is alcohol miscible in
    Water and histoclear
  • Is histoclear miscible with water
    no
  • What does eosin bind to
    Proteins
  • What type of stain is eosin
    Acidic
  • What does eosin stain
    proteins stain red
  • What does haematoxylin stain
    DNA blue
  • What type of stain is haemotoxylin
    Basic
  • Is haemotoxylin water soluble
    Yes
  • What charge molecules does eosin bind to
    Positive
  • Does the brightfield microscope use fixed lenses
    Yes
  • What does a reduction in the condensor aperture diameter of a brightfield microscope produce
    Increased contrast
  • What type of cells is a brightfield microscope used for
    living
  • What happens to depth of field as the magnification of a brightfield microscope increases
    It will increase
  • What is the maximum thickness of specimen for a brightfield microscope
    10 microns
  • What is the equation for resolution of a light microscope
    Resolution = (0.61 * lambda) / NA. Where NA = n sin alpha and Lambda is the wavelength.
  • What is NA in the resolution equation
    It is n Sin alpha.
    Where alpha is the angle that light enters the lens it is often 70 degrees.
    n is the refractive index and is 1 for air.
  • Calculate the resolution when The wavelength of light is 450 nm [show working to 3 sig fig]
    Resolution = (0.61 * 450) / (1 * sin 70) = 292 nm = 0.292 microns
  • What is the refractive index of oil
    1.5
  • Which microscope parameter has the highest improvement of resolution [Refer to resolution equation]
    Wavelength
  • Why is a sucrose solution of 0.5M used to extract chloroplasts
    The 0.5M is isotonic to the chloroplasts and so prevents them from swelling and bursting.
  • What does isotonic mean
    The concentration of solute is equal outside and inside the solution.
  • What is a hypotonic solution
    The concentration of solute is lower outside than inside the cell.
  • What is the effect of an isotonic solution
    There is no net movement of water
  • What is the effect of a hypotonic solution
    The net movement of water is into the cell causing it to swell and burst.
  • What is the effect of a hypertonic solution
    The net movement of water is out of the cell and causes it to shrink.
  • What is a hypertonic solution
    The concentration of solute is higher inside the cell than outside.
  • What is the effect of criticcal point drying of extracts for microscopic analysis
    It prevents shrinking
  • What is used for critical point drying
    Liquid carbon dioxide
  • Label the images and state where they come from
    These are from a plant cell.
    A) Stomata
    B) Vascular bundle
    C) Chloroplast
    D) Granum