Sophia ZubeJanuary 12, 2014

Period 3

Photosynthesis Lab – Different Colored Light

Hypothesis: If different colored lights are used, then the photosynthetic rates will change because they will be affected by the different frequencies of light.

Materials:

. 0.2% sodium bicarbonate solution

. Liquid soap (5mL soap: 250mL water)

. Plastic Syringe (6)

. Pipette (6)

. Spinach leaves

. A hole puncher

. A 250 mL beaker (6)

. Timer (6)

. 6 lamps (100 W)

. Different colored plastics (red, blue, green, yellow, orange)

. Rubberbands (5)

Procedure

Different groups will be assigned different colors. There will be one lamp per group

1) Prepare lamps by wrapping the chosen colored plastic over the lampshade part and securing it with a rubber band. One group’s lamp will not have colored plastic. This will be the control.

2) In a beaker, put 150 mL of the bicarbonate solution and 250ul of soap solution (using a pipette). Try to keep bubbles from forming..

3) Cut 20 discs from the spinach leaves, avoiding the veins.4) Put the spinach discs inside a syringe, removing and then replacing the plunger.

5) Put 5 mL of the solution created in Step 1 into the syringe. Push out air bubbles. 6) Put a finger on the top of a syringe and pull down and up until all the spinach discs have

sunk to the bottom. Do not remove finger. 7) Pour the discs and solution into the beaker.8) Put the beaker under the lamp with your particular colored plastic (or no plastic if you are

the control group)9) Keep track of how many discs have floated up for each consecutive minute until all are at

the top.

Expected Results:

I expect that the control group will have the greatest rate of photosynthesis. The lamps with red and blue plastic will probably have the next greatest rates. The last three (yellow, green, and orange) are most reflected because of pigments in the chlorophyll so will have the lower rates, with green most likely being the lowest.

Why These Results:

The control will have the greatest rate because the plant will not be limited in the frequencies available. It will be able to ‘choose’ what it needs/wants. The red and blue plastics will have the next highest rates because plants utilize these frequencies the most (they don’t correspond to the colors found in chlorophyll). The yellow and orange will have lower rates of photosynthesis because of cartenoids and xanthopyll pigments found in plants. This light will be reflected. The lowest rate of photosynthesis is green because this pigment is the most prominent in plants because of chlorophyll.