An Investigation on the Effects of Light Intensity on Photosynthesis

Plan

I plan to investigate how light intensity affects the rate of photosynthesis in pondweed. The rate of photosynthesis will be measured by the number of bubbles given off (considering that oxygen is produced as a waste gas during photosynthesis). The light intensity is measured by the distance between the lamp and pondweed.

Fair test:

Fix: the amount of pondweed, the amount of water and sodium hydrogen carbonate solution in the test tube, the time allowed for each experiment

Change: the distance from the lamp to the pondweed (light intensity)

Measure: the number of bubbles given off by the pondweed, the temperature of the water bath

Variables:

The following are factors that affect the rate of photosynthesis:

Light – quality and quantity

Carbon dioxide

Temperature

Water

Chlorophyll

Light is needed to provide the energy for the reaction to take place because it is an endothermic reaction. This is the variable that I am going to change, the light intensity will be measured by the distance from the lamp to the pondweed. The quality of the light will be kept the same because the same lamp will be used.

Carbon dioxide is needed because the element are needed to produce glucose which is what the plant is trying to make. This can be controlled by having a fixed amount of sodium hydrogen carbonate solution in the test tube.

The temperature needs to be controlled at higher temperatures the rate of reaction speeds up. It will be controlled by putting the plant in a water bath to maintain the same temperature

Water is needed for photosynthesis because the elements are needed to make glucose. This can be controlled by having a fixed amount of water in the test tube for each experiment.

If there is more chlorophyll then more light can be trapped which will speed up the process. This needs to be controlled by using the same piece of pondweed for the experiments.

The limiting factor is the