BIO 104 4/22/96

Laboratory Preparation Lecture #3

CONTACT LENSES ARE NOT RECOMMENDED FOR STUDENTS DURING THIS LAB:
PLEASE WEAR GLASSES OR SAFETY GOGGLES
I. Introduction to Photosynthesis
     -transpiration carries water through the plant; this water
is
     used during photosynthesis
II. Basic Ideas
     A. photosynthesis is essential to life on this planet
          a. food
          b. air
     1) Light Dependant Reactions
          CO2+H2O yields (light is needed) C6H12O6+O2+H20
          -main products are sugars, oxygen and water
          -plants also produce secondary plant compounds
     2) Light Independent Reactions
          -Know the difference in the two reactions
     B. Structures of leaves
          -stomates
               -located on the underside of the leaf
          -know structures in the leaf
III. Light and Photosynthesis
     A. Light
     -wavelengths are measured in nanometers 10-9 meters
     -electromagnetic spectrum  
     see page 53 in lab manual
     B. Reflectance and Absorbance
     -Plants
          -green wavelength is not used for photosynthesis; the rest of the
          wavelengths are absorbed
          -white light is the reflection of all wavelengths
          -black light is the absorption of all wavelengths
     C. Pigments
          -absorb light to use in photosynthesis
          1) chlorophyll A and B
               -reflect green 560 nm
               -absorbs blue 400-450 nm and red 650-700 nm
          -During fall the leaves turn yellow and orange due to the
          pigments xanthophyll and carotene which absorb 460-550 nm

IV. Paper Chromatography
     1. take the paper and mark a specified distance down from
the  top and up from the bottom
     2. streak plant material along the line you marked at the
     bottom of the paper
     3. place the paper in a jar of solvent
          -the solvent will carry the pigments at different rates
          up the paper; so be sure to take the paper out when the
          solvent reaches the top line
     4. Calculations
          Ratio of fronts value= Pigment distance/solvent
distance
V. Jars of Algae
     -used to test photosynthesis
     -only  use certain lights
          1. dark or black light
          2. white light
          3. green light
          4. red light
     -you will measure the amount of dissolved oxygen with a 
     dissolved oxygen probe