Bio lab final

• Independent variable


  Variable that which you are varying to determine its effect
• Dependent variable


  Variable that which you are measuring to see if there was an effect
• Potentially confounding variable


  Factors that you will keep constant so that they do not affect your results
• Alternative hypothesis


  There is an effect of the independent variable on the dependent variable
• Null hypothesis


  There is no effect of the independent variable on the dependent variable
• Ocular lens


  Set of lenses at the top of the scope through which you look
• Platform stage


  Moved vertically or horizontally by turning the coarse adjustment knob and the fine adjustment knob in order to focus the image
• Coarse adjustment


  Used for initial focusing at low power only
• Fine adjustment


  Makes very slight changes, allows for precision focusing and can be used with low or high power objectives
• Microscope focusing


  1. Turn on power and open software

  2. Press red button to turn on camera

  3. Click "Inquire" tab

  4. Place sample on stage

  5. Start with 4X, focus

  6. Move up to 10X and 40X, focus using fine adjustment
• Total magnification


  10 multiplied by the objective
• Working distance


  Space between the objective lens and the slide, decreases with increased magnification
• Field of view


  Size of the area through the oculars, the greater the magnification the smaller the field of view
• Stage micrometer


  Very tiny ruler mounted on a microscope slide, the smallest increment is 10 µm and the whole ruler is 1000 µm = 1 mm
• One small space (increment) on a stage micrometer is 10 µm
• Determining microscope scale


  1. Scale with the ratio of pixels to µm

  2. Scale changes for each objective
• Calculating cell size


  Cell size in pixels * (µm/pixels scale) = cell size in µm
• Spectrophotometer


  Measures the amount of photons absorbed after it passes through a sample solution
• Blank


  Control for the experiment so the solution the substance is in does not affect the values
• Using a spectrophotometer


  1. Properly fill, dry, and insert a cuvette

  2. Collect an absorption spectrum in LoggerPro

  3. Interpret an absorption spectrum to determine which wavelengths/colors are absorbed or reflected by the sample

  4. Determine the peak absorbance value and wavelength
• Paper chromatography


  Non-polar pigments dissolve in the non-polar solvent and move up the paper, while the polar paper attracts the less non-polar pigments
• Polar bond


  Unequal sharing of electrons due to one atom being more electronegative
• Non-polar bond


  Equal sharing of electrons between the atoms
• Rf value


  Distance traveled by the pigment from the origin divided by the distance traveled by the solvent from the origin
• Rf value of a pigment


  Relates to its solubility in the solvent and its polarity relative to other pigments
• Order of pigments from most non-polar to least non-polar: carotenes, xanthophylls, chlorophyll a, chlorophyll b
• If the solvent goes above the leaf extract

  The pigments will dissolve in the solvent, turning the liquid green
• If using water as the solvent


  The pigments will remain at the origin as they are non-polar and will not dissolve in the polar water
• Absorption spectrum


  Peaks are colors that are being absorbed, low parts are the color(s) being reflected
• Serological pipetting


  1. Properly pipette a volume of liquid using 5ml and 10ml serological pipettes with pumps

  2. Determine the density of an unknown solution by pipetting an assigned volume, determining its mass, and then calculating the density
• You must tare the scale with the empty beaker on it in order to obtain the mass of the liquid
• Osmosis


  A process by which water passes through a semipermeable membrane from a place of high concentration of water to low concentration of water
• Semipermeable membrane


  Allows certain substances to pass through but not others
• Calculating percent change in mass

  % change = [(final mass - initial mass) / initial mass] * 100
• Potato cores gaining, losing, or not changing mass


  Depends on the concentration of sucrose solution relative to inside the cell
• Phospholipid


  Hydrophilic head and hydrophobic tail
• Double bond in fatty acid tail

  Makes the lipid bilayer more fluid
• Small non-polar molecules


  More easily able to cross directly through the plasma membrane than ions like Na+ or Cl-
• Isotonic, hypertonic, hypotonic


  Relative to the inside of a cell
• DNA extraction from strawberries

  1. Mashing the strawberry

  2. DNA extraction buffer (soap, salt, water)

  3. Filtering

  4. Meat tenderizer

  5. Alcohol