Observe a Coleus or Geranium plant that had been covered. Note: do parts B and D first, then part A while waiting.

1. Sketch a partially covered leaf.
2. Boil the leaf to remove pigments other than chlorophyll.
3. Place leaf in hot ethanol to extract the chlorophyll.
4. Rinse leaf and place in petri dish.
5. Soak the leaf in potassium iodide (I₂KI) for 5 minutes, then rinse. Dark brown areas of the leaf indicate presence of starch.

Carbon dioxide forms carbonic acid in water: CO₂ + H₂O -> H₂CO₃

1. Use Phenol Red as a pH indicator: red in basic and neutral solutions, turning yellow in acid.
   Dilute the Phenol Red 1/10 tap water or distilled water.
   Make one batch for the class: add 50 ml Phenol Red to 450 ml of water.
2. Make the solution acidic (yellow) by blowing CO₂ into the solution. This will provide a source of carbon for photosynthesis.
3. Cut Elodea to make 2 sets of 5-cm and 10-cm lengths, place in screw-top test tubes.
4. One set will be under lights, the other in a dark cabinet (wrap with aluminum foil).
5. Treat for about 60 minutes, note color changes.

Demonstration of gas-trapping system. Glowing splint indicates presence of oxygen.

paper chromatography to extract chlorophylls, carotenoids and xanthophylls (a polar carotenoid).

1. Grind spinach in acetone.
2. Filter the solution. NOTE: do not over-rinse; you only need a tiny, concentrated sample for the chromatography.

1. Cut paper 2cm longer than test tubes.
2. Use capillary pipet to place a spot of extract on the paper, about 1 cm from bottom.
3. Mark the spot with a pencil.
4. Place strip into test tube containing solvent (acetone and toluene). The solution, with the suspended pigments, should move up by capillary action.
5. Observe after about 30-60 minutes.

Use a band from chromatography paper or extract in a cuvette.

1. Warm up Spectronic 20D for 15 minutes.
2. See Appendix 3 p. 201
3. Record absorbance from 400 to 700 nm.
4. Remove cuvette.