Introduction: Photosynthesis occurs in plants where the light energy changes to chemical energy. This process occurs in the chloroplast of the plant cell in order to have gas exchange in the organism. Purpose: To measure the effect of light intensity on the rate of photosynthesis in the leaf cells. Hypothesis: The higher the concentration of the sodium bicarbonate solution, the faster the leaf of the plant will rise to the surface of the water in the beaker, the higher the rate of photosynthesis. Materials: Fresh green leaf, hole punch, 50 mL plastic syringe, stop watch, 1 x 25mL beakers, 50 mL measuring cylinder, forceps, distilled water, 2%, 3%, 4%, 5% of sodium bicarbonate solution, overhead projector and sieve. Method: 1. The leaf is cut using a hole punch and are immediately transferred to a 100 mL beaker containing distilled water. 2. The disc leaves are transferred into a 50 mL syringe filled with 20 mL of distilled water and the air is expelled. The small hole in the tip of the syringe and covered with finger and the plunger is pulled out slowly until the disc leaf is sink at the bottom of the syringe. 3. 4 x 25 mL of the beakers are labelled A to F and each beaker is placed with 2%, 3%, 4% and 6% of sodium bicarbonate solution. 4. The water containing the disc leaves is poured through the sieve and 10 discs are transferred into each of the 4 beakers containing 25 mL of 2%, 3%, 4% and 6% of sodium bicarbonate on the overhead projector (OHP). 5. The OHP is turned on and the stopwatch is started immediately. The time for each disc leaf to rise to the surface of the water in recorded. 6. All the results are recorded in a table and a graph is drawled.
Rate of photosynthesis
| Time for leaf disc to float (s)| |
NaHCO3 conc.%| 1st| 2nd| 3rd| 4th| 5th| 6th| 7th| 8th| Average Time (s)| 2| 3.50| 4.00| 4.00| 4.00| 4.00| 4.07| 5.15| 5.15| 4.23| 3| 2.14| 4.55| 4.55| 4.55| 4.55| 5.40|...