Photosynthesis Virtual Labs.

Lab 1: Glencoe Photosynthesis Lab

http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS12/LS12.html

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 the most energy is absorbed by the color blue, and the least energy is absorbed by the color green, then the color green causes the least plant growth and the color blue causes the most plant growth.

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?

We tested our hypothesis by placing the different plants side by side, growing half with red light and half with green light. The variables controlled were the type of plants, the brightness of light, and the days of growth. We changed the color of the light to compare our growth results.

Results:

Filter Color	Spinach Avg. Height (cm)	Radish Avg. Height (cm)	Lettuce Avg. Height (cm)
Red	18	14	12
Orange	14	8	6
Green	2	2	3
Blue	19	14	13
Violet	16	11	9

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.

 Our data supported our hypothesis, because it shows that the average height of all the plants are greater under blue light, and lower under green light. The blue lighted plants grew the most, and the green lighted plants grew the least. This is because the color green is reflected by plants, because it contains chlorophyll, a green colored pigment. Generally the lettuce seeds grew to be the shortest, regardless of the color, and the spinach grew the most, while the radish was in between.

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

  According to our data, we can conclude that the color blue causes the most plant growth. Their wavelengths cause them to be best absorbed by plants, increasing plant growth.

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

  Under white light, there would be a balance of the colors, making it a neutral under the spectrum, giving medium growth results.

Site 2: Photolab

http://www.kscience.co.uk/animations/photolab.swf

This simulation allows you to manipulate many variables. You already observed how light colors will affect the growth of a plant, in this simulation you can directly measure the rate of photosynthesis by counting the number of bubbles of oxygen that are released.

There are 3 other potential variables you could test with this simulation: amount of carbon dioxide, light intensity, and temperature.

Choose one variable and design and experiment that would test how this factor affects the rate of photosynthesis. Remember, that when designing an experiment, you need to keep all variables constant except the one you are testing. Collect data and write a lab report of your findings that includes:

• Question
• Hypothesis
• Experimental parameters (in other words, what is the dependent variable, independent variable, constants, and control?)
• Data table
• Conclusion (Just 1st and 3rd paragraphs since there's no way to make errors in a virtual lab)

*Type your question, hypothesis, etc. below.  When done, submit this document via Canvas.  You may also copy and paste it into your blog.

Question: How does light intensity affect the rate of photosynthesis?

Hypothesis: If white light contains all of the colors of the visible light spectrum, then a plant grown under a light of higher intensity will grow at a faster rate under photosynthesis.

Experimental Parameters:

-Dependent variable: rate of photosynthesis

-Independent variable: light intensity

-Control: neutral light intensity (25)

-Constants: the plants, the amount of carbon dioxide(50% of bottle) , the time (45 seconds), the color of light(white), and temperature (10°)

Data Table: Rate of Photosynthesis

Light Intensity	15	25	35	50
# of oxygen bubbles	9	14	16	18

Conclusion:   In this lab we asked the question, “How does light intensity affect the rate of photosynthesis?” We found that a higher intensity of light produced more oxygen, speeding up the rate of photosynthesis. Our data shows the green plant produced more oxygen under a higher intensity of white light, than a lower intensity of white light. At a light intensity of 15, 9 oxygen bubbles appeared throughout the 45 seconds. At a light intensity of 25, 14 oxygen bubbles were produced during that time. At a light intensity of 35, 16 oxygen bubbles appeared.  At a light intensity of 50, 18 oxygen bubbles appeared during the 45 second test. Based on what we learned in the vodcasts, light is one of the 3 main elements necessary in carrying out the oxygen producing process of photosynthesis. With a higher intensity of light absorbed by the plant, the plant is therefore able to produce more oxygen through photosynthesis. This data supports our claim because it shows how with a greater light intensity, a plant will be able to create more oxygen by absorbing more light.

This lab was done to demonstrate how the quantity of a reactant, like light intensity, can affect the quantity of the remaining products of photosynthesis, like oxygen. From this lab, I learned about the key factors needed to carry out photosynthesis, and how they can affect the products, helping me understand the concept of the chemical formula of photosynthesis. Based on my experience from this lab, I could apply what I learned to another situation where I am growing a plant, because I now know what the optimal conditions are, regarding temperature, light intensity, and color.