Glencoe Photosynthesis Lab

Analysis Questions

1. Make a hypothesis about which color in the visible spectrum causes the most plant growth and which color in the visible spectrum causes the least plant growth?

If a plant is put under red or blue light, the plant will grow a lot more than it would under green or yellow light.

Red light and blue light would cause the most plant growth because plants absorb a lot of red and blue light. Green light and yellow light would cause the least plant growth because  green and yellow light are reflected off the plant.

2. How did you test your hypothesis? Which variables did you control in your experiment and which variable did you change in order to compare your growth results?

I tested my hypothesis by putting three different seeds underneath different colored lights. The types of seeds remained the same, but each time, I changed the color of the light to see how each of the different colored light affected the plant’s growth.

Results:

Filter Color	Spinach Avg. Height (cm)	Radish Avg. Height (cm)	Lettuce Avg. Height (cm)
Red	18 cm	13 cm	11 cm
Orange	15 cm	8 cm	6.67 cm
Green	2 cm	1.167 cm	3 cm
Blue	19 cm	14.67 cm	13 cm
Violet	16.167 cm	9.33 cm	7.83 cm

3. Analyze the results of your experiment. Did your data support your hypothesis? Explain. If you conducted tests with more than one type of seed, explain any differences or similarities you found among types of seeds.

The data did support the hypothesis. While the plants were underneath the red and blue light, they grew the most. While the plants were under the green light, the plants grew the least. For all three seeds, each plant grew the most under red and blue light.

4. What conclusions can you draw about which color in the visible spectrum causes the most plant growth?

Red, blue, and violet light will cause the most plant growth. Violet light contains red light and blue light so it will also be effective when growing plants.

5. Given that white light contains all colors of the spectrum, what growth results would you expect under white light?

White light would lead to even more growth than just having one colored lights. Even though green light does not cause much plant growth, the plant will still grow a little. The green light will add a little more growth when combined with the other lights.


Link to virtual lab: http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS12/LS12.html