Rate of Photosynthesis

The rate of photosynthesis can be affected by sunlight, temperature, CO2 and O2, and any factor that influences the production of chlorophyll, enzymes, or energy carriers. The rate of photosynthesis will always correspond to that factor which is in least supply. Its rate will only increase when its supply is increased.

An experiment on the effect of light intensity can be done to measure the rate of photosynthesis. You can expose samples of a plant to various light intensities, and determine the relative rates of photosynthesis by observing changes in pH. You would need: pH paper, 5 beakers, 5 samples of the same plant, graduated cylinder, baking soda, 200-watt light source, distilled water, stirring rod. Each beaker would be labeled. Using the graduated cylinder, you would pour 200 mL of distilled water into each beaker. Stir in the same amount of baking soda to each of the beakers until the chemical is dissolved. Next, you would test the pH of the five solutions. Results would be recorded. After that, you would obtain the 5 samples of the plant and place one in each beaker. Then, you could place one beaker in darkness, another in room light, and the rest several meters away from the 200-watt bulb. After several minutes, you could check the pH of the solution of the beaker with another pH paper. Again, you record the results and study the difference of pH levels of each beaker.

From these results, you will be able to say that an increase in light intensity does certainly increase the rate of photosynthesis. The gradual decrease in the rate of increase of the rate of photosynthesis can be attributed to the other factors limiting the rate of photosynthesis. As light intensity increases, the photosynthetic rate is being limited by certain factors, such as CO2 and temperature. These factors do not immediately limit the rate of photosynthesis, but rather gradually. As light intensity increases further, so the rate of photosynthesis is being limited by other factors more and more, until the rate of photosynthesis is constant, and so is almost certainly limited in full by another factor.

Photosynthesis is light dependent. At low light intensities, this may become the limiting factor. For this reason, plants grow better outdoors, rather than in the house. There is also a level above which photosynthesis cannot take place any faster