||Plants need photosynthesis to grow and survive. Photosynthesis occurs when sunlight hits a plant, allowing a chemical process to take place that creates energy for plants. Some parts of this are confusing, like what elements are also needed for photosynthesis, or how exactly sunlight is used in that process.
||We want to know what kind of light is needed for plants to photosynthesize other than natural light. We want to test different types of lightbulbs to see which is the most effective. Does changing the lightbulb from which a plant receives light affect the plant's rate of photosynthesis?
||We think the lightbulb with the most wattage will cause the plants to photosynthesize the quickest, since the light is more intense. We don't know yet if there is a certain light level we have to achieve or if we just need a lot of light.
For our experiment we will need spinach, a syringe, a hole puncher, a marker, a ruler, a lamp, clear cups (one for each lightbulb), and at least 2 different lights/lightbulbs (we planned to use LED, 40w incandescent, 100w incandescent lights; our data uses more types of lights as our group members cannot all access the same materials).
Procedure: *If using 3 different light sources
1. Labeling each clear cup to match its respective lightbulb, (example: 100w), mark two inches up from the bottom each cup and fill each cup with water up to the mark.
2. 1 tsp of baking soda will be put in each cup.
3. 36 spinach pieces will be infiltrated using a syringe. In each cup, at least 10 pieces must sink.
4. Place a cup under its respective light and turn on the lamp. The cups should be placed the same distance from their lamps, and the light source should face the cup.
5. For each cup, timer will be started for 10 minutes when the light is turned on. The number of spinach pieces that float to the top of each individual cup each minute will be recorded (example: 1 min, 1 piece).
The amount of water (2in), spinach pieces (shape and amount -- minimum 10 pieces), amount of baking soda (1tsp), and cups are our control variables and stay the same between the different trials.
The type of light/source from which a cup of spinach is exposed to is the independent variable and changes between the trials.
Our dependent variable is the number of spinach pieces that floats to the top of each cup each minute--these numbers may vary depending on what each trial entails.
||Light type does affect a plant's rate of photosynthesis. Our results did not match our predictions since the LED lights underperformed all of the incandescent lights. The 75w lights resulted in the most spinach pieces to float each minute and had the first pieces to begin floating for the majority of the trials. From the results, our group believes that 75w lightbulbs may be the best lights for plant photosynthesis when growing plants indoors. We think that, possibly, the LED lights were brighter but used less energy than the incandescent lights; this idea that the LED emits a smaller amount of energy could explain why our prediction was incorrect.
||High School Students (Grades 9,10,11,12)
||Ottawa Township High School