The last observation was the effects of leaves on PH. To perform this, distilled water, elodea leaves, and phenol red were put into a test tube. Phenol red is a dye that red in basic solutions and yellow in acidic solutions. Since distilled water in slightly basic, it test tube appeared red. To turn the water acidic, carbon dioxide (CO2) was blown into the test tube via a straw. When placed under a light, the elodea cells were able to photosynthesize and create oxygen, which turned the water back to a reddish color. .
From these three demonstrations, two hypotheses about photosynthesis were created to be tested. The two hypotheses were: 1. Heats speeds up the rate of photosynthesis. 2. Light directly increases the rate of photosynthesis. These to hypotheses were tested and conclusion can be made from the data.
Method and Materials:.
Hypothesis 1: Heats speeds up the rate of photosynthesis. .
The testing for this hypothesis was done by using three test tubes, aluminum foil, distilled water, phenol red, and elodea leaves. In each test tube was placed 3 mL of distilled water, 3 mL of phenol red, and a couple elodea leaves. Carbon dioxide was added to each test tube by blowing into them through a straw. This turned the water in the test tube yellow due to its slight acidic PH. As mentioned before, phenol red is a dye that is red in basic solutions and yellow in acidic. Each test tube was then wrapped in aluminum foil so that light would not be a factor during testing. One test tube was then placed under a light for heat, one in room temperature, and one in an ice bath. Every five minutes, the test tubes were unwrapped and observations of the color inside the test tubes were recorded. This was done in five minute increments for twenty minutes. If there was to be a quicker rate in photosynthesis in any of the test tubes, then the water in that test tube would be a reddish color.
Hypothesis 2: Light directly affects the rate of photosynthesis.