1. How Different Colored Light Bulbs Affect the Rate of Photosynthesis on Plants By: Veronica Natale, Natasha Ivanova, and Andrew Grimm

2. How Photosynthesis Works Occurs in plants, some bacteria and protistans (various one-celled organisms). Occurs when sunlight converts carbon dioxide into sugar (ATP and NADPH) Two sections: light-dependent reactions and light-independent reactions (Calvin Cycle) Photosynthesis happens in the stroma of chloroplasts.

3. Light Independent Reactions Photosynthesis usually occurs in the leaves. CO2 and O2 enter and exit the leaves through the stomata. The chlorophyll in the chloroplasts inside leaf cells absorbs sunlight. The light dependent reaction happens when solar energy is captured to make a molecule called ATP.

4. Calvin Cycle Chlorophyll forms “antenna complexes”. Antenna complexes transfer light energy to one of two photochemical reaction centers (Photosystem I & II) Photochemical reaction centers are located on the thylakoid membrane of the chloroplast. Excited electrons are transferred to electron acceptors, leaving the reaction center in an oxidized state. The light-independent reactions (Calvin Cycle) produce glucose by using ATP and NADPH that are formed from the light-dependent reactions.

5. Photorespiration Occurs under high light intensity, hot weather, limited water conditions. Alters sugar phosphates into carbon dioxide. Occurs when rubisco accepts O2 instead of CO2 and produces no ATP. Occurs when plants’ stomatas are shut and the O2 concentration in the leaf exceeds that of CO2.

6. Wavelengths Light that may be seen by humans is called “visible light“ (only on the visible spectrum). It has a wavelength range of about 400 - 700 nanometers (nm) Wavelength- distance between a peak or crest of a wave of energy and the next peak or crest. Nanometer- one billionth of a meter Covers an array of colors from violet to red. Visible colors (shortest wavelengths to longest) : violet, blue, green, yellow, orange, red. Ultraviolet radiation- shorter wavelength than violet Infrared light- longer wavelength than visible red light. White light- a mixture of the colors of the visible Black- total absence of light.

7. Rate of Photosynthesis Rate of photosynthesis- defined by the rate of oxygen production per unit mass (or area) of green plant tissues. Light, the carbon dioxide, temperature, water supply, and availability of minerals are the most important factors that directly affect the rate of photosynthesis in land plants. Factors such as plants health, maturity, and whether or not it is in flowering also affects it’s rate of photosynthesis.

8. Our Experiment The higher the level of C02, the lower the rate of photosynthesis The lower the level of C02,the higher the rate of photosynthesis. Why? Because plants use C02 and H20 to create sugar and oxygen Measuring the levels of CO2 would tell us if the level of carbon dioxide was high or low.

9. Variables Independent variable: Rate of Photosynthesis Dependent variable: Color of Light Controlled variables: same leaf of same plant, same amount of time running tests Constant: normal light

15. Final Results… The highest levels of CO2 were produced with the blue and red light (produced same amount). Second highest was green light. White light decreased amount of C02 and increased 02 after a little while. Photosynthesis occurred only from the white light according to our results. The colored lights allowed photorespiration Can assume that blue, red and green lights decrease rate of photosynthesis in plants while white light increased it. Why could this be? The sun produces white light. White light is a mixture of all the colors on the visible spectrum.