By Sofie Inwood
Aim: To determine whether chlorophyll and light is necessary for starch formation.
Hypothesis: Chlorophyll and light are both necessary for starch formation.
* 600mL beaker * Access to water * Safety glasses * Bunsen burner * Tripod * Gauze mat * A large white evaporating dish * Scissors and forceps| * Glass stirring rod * Test tube rack * Test-tube (30mm x 180mm) * Methylated spirits * Iodine solution * 100mL beaker * Soft green leaves * Rubber gloves|
Iodine Solution stains skin and clothesIt’s harmful with contact with eye or consumed| Wear rubber gloves, be careful with solutionDon’t touch eyes, keep away from mouth| Methylated spirits - poisonous if consumed - consumption could result in blindness - can irritate skin/eyes| Do not put finger to mouth after touchingWear safety goggles and rubber gloves|
1. Prepare leaves the lesson before. Put a strip of alluminium foil over the middle of completely green leaves. On variegated leaves put the foil in the middle section leaving a border around the edge uncovered. 2. After 24 hours (next lesson), bring the leaves into classroom. 3. Set up Bunsen burner, tripod and gauze mat.
4. Bring about 75mL of water in 100mL beaker to the boil. Take foil of leaves and place them in the beaker. 5. Place any leaves to be tested in the boiling water until they go limp (1-2 mins). This kills the cells and softens the leaves. Remove the leaves with forceps and place them in an evaporating dish. 6. Collect a tube of methylated spirits. Use forceps to put the softened leaves into tubes. Place the tube in the nearly boiling water. In a short time the alcohol will start to boil and it will take on a green pigment from the leaves...