|Explore||We know that plants require carbon dioxide and energy from the sunlight to photosynthesize/grow, and are interested to learn if the color of light being absorbed will affect the plants growth rates.|
|Research Question||How do the effects of photosynthesis change when impacted by different colors of light?|
|Predictions||If we alter a plant’s light source color, then their heights and rates of photosynthesis will vary because their chloroplasts will absorb different colors of light in various ways. We believe that the red will show more growth than the green.|
|Experimental Design||1.Soda bottles were cut and stacked to allow water to drip through. 2.3, 1000 mL samples of potting soil were measured. 3.3, 5g samples of grass seed were measured. 4.Potting soil was placed in bottle, followed by grass seed. 5.Each pot was watered with 150 mL of water. 6.Respective bottles...|
|Conclusion||Our hypothesis appeared to be partially accurate because the light sources did alter the rate of growth for each plant, but not in the exact ways that we predicted. The control showed the most normal growth with evenly distributed roots. The red and green each showed dense root growth because...|
Hey Team! I took a look at your final presentation and loved it! You did a very nice job of incorporating photos of your experiment. As a scientist, being able to show your experiment visually is a powerful tool for communicating your research.
One statement in your conclusion slide jumped out at me: "The red and green each showed dense root growth because they were required to search the most to photosynthesize"
I mentioned the term "etiolation" in an earlier post, and I think this is what you're describing here. When plants don't get sufficient light energy for photosynthesis, they will grow faster in order to "move" into stronger light (helps explain why the red and green lit grass was taller than the control). This type of growth results in weaker tissues, though, which helps explain why the dry weight of the red and green lit grass was lower than the control group.
Comparing the red and green light groups, the grass under green light looks like it was more etiolated (taller height, lower dry weight) than the grass under red light. This makes sense because as you predicted, red light is absorbed more effectively than green light.
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We have just cleaned up a follow-up lab where we placed radish seeds in a petri dish and covered them with the appropriate colored cellophane and placed them under light. The data we collected from that follow up to our hypothesis was quite different from the original grass lab. The hypothesis was much more evident in this lab, as we could tell just by looking what had the most growth. In the red petri dish, the longest sprout root to shoot measured 15 cm, the green measured 6.5 and the control 11. It made a lot more sense than our grass lab, where the grass in the green bottle grew the most...
The Red container also had the most overall germination of radish seeds, sprouting 15 plants while the other 2 sprouted 12. These measurements were taken after 7 days. I liked this lab better because it really supported our original hypothesis that the red container would have the most overall growth and germination. We are currently measuring the grasses grown in the bottles, and will update you soon!
We came to school today to find that our grass did not grow. In fact, nobody's grass grew. Mrs. Bradley is going to purchase new grass seed, but we may decide to use radish seed and retry the lab, in hopes that it will work and we will see some germination. The soil looks well saturated and moist, and the seeds are evenly spread, as well as there being direct light, so we think the seeds may just be old and...not good. Oh well, science is about failure and retesting things!
Do you have any predictions or hypotheses for your experiment? Which grass do you think will grow the most? The least? Why do you think that?
Hi Julia, today we have started the lab. Our procedure:
By looking at our pictures that we sent, we set up 3 (2 liter) bottles cut in half into a drainage source which were two other bottles and a pickle jar.
We filled each bottle with 1000 mL of potting soil, then measured out 5 grams of grass seed into three cups and spread them evenly into each bottle and turned the soil. So each bottle contained 1000 mL of soil and 5 grams of grass seed. We then watered each subject with 150 mL of water, then covered two bottles all the way around and on top with cellophane, one with red and one with green, and left our control uncovered. All three bottles are under an uncovered lamp light and as a key for quick reference we labeled each bottle as such
Bottle with Red cellophane wrap: A
Bottle with Green cellophane wrap: B
Bottle with no cellophane wrap/ Control: C
We uploaded some pictures to enhance our description of the lab setup. They uploaded sideways, but hopefully they are clear!
Julia, in response to your personal questions! I love science, I am planning on getting a Bachelor's in Biology with a teaching license in college, so I can be a high school biology teacher (I'd love to teach other branches of science as well). Science is my all time favorite subject because it is so hands-on and really makes you think! I also love math because it makes so much sense to me, and I just love finding solutions to problems; I'm in calculus right now and surprisingly enjoying it. My hobbies are band, theatre, cooking and hiking! I have three dogs, a cat, and a rat. Might I also mention my sister is a Biology major and is concentrating in ecology and evolution, she also really loves herpetology and often goes out "herping" with her class.
Hi Julia, it is so nice to hear from you! We will update you about ourselves tonight once we are home. However, as far as the labs are concerned..During the light/dark leaf lab, the chads floated because photosynthesis was occurring and they were releasing oxygen (causing the little bubbles on the leaves). We do believe that more would sink if they were left in the dark for a few days because 2 of our chads actually did sink the dark. They sink because they can no longer photosynthesize, as light is a major component needed. For our independent lab, we are not sure exactly how many grass seeds to plant because we do not know the size of the container. But, we will ensure that every cup has an equal amount. We're planning on using small clear plastic cups, so how many would you suggest? To keep other light from coming in and altering the lab, we will keep the plants in a confined dark area. Concerning your last question, we were thinking the same thing, perhaps a regular lamp would be better to use as the control, do you agree? We cannot wait to hear from you again and we are so excited to work with you as we are all big science nerds! ;)
Independent Lab: I think this sounds like a good experiment. It’s very similar to what some of my college students have done in the labs that I teach! I have some questions about your methods.
1. How many grass seeds will you plant in each vase?
2. The purpose of the cellophane is to make the light reaching your plants all one color, right? If the cellophane is placed on the lamp, how will you ensure that no other light is reaching your plants?
3. Do you think there is a difference in the amount of energy coming from sunlight versus light from a lamp? Could this be problematic for your control group?
Ah! I should introduce myself! Obviously my name is Julia. I'm a graduate student at the University of Dayton in Dayton, Ohio. I'm working on my Ph.D. in Biology. I study forest ecology - how plant communities change across space and through time. This includes identifying trees, shrubs, seedlings, saplings, and herbaceous (non-woody) plant species. So it's safe to say that I know a lot of plants!
I have two cats, like to kayak, try to bike to work as often as possible, and enjoy cooking and baking on the weekends.
What about you all? What are your favorite subjects in school? Do you enjoy science? Do you have any pets? What are your hobbies?
I love your team photo by the way. :)
Oh my gosh, you guys! I'm so sorry that I haven't been responding! I kept waiting for e-mails to notify me, but wasn't getting any. Turns out I have to subscribe to the project feed.
The initial light/dark experiment sounds like it went well. Can you describe what was occurring inside the leaf discs that caused them to float?
I’m not surprised that none of the chads sank in the dark. I’ve taught a similar lab in a college class and it seems to take a long time for leaf discs to sink in the dark. Do you think that they would eventually sink if you kept them in the dark for a few days?
Our independent lab!!!
We will be testing the rate of photosynthesis under different light sources. We will be growing grass under three different light sources. Our control group will be grown under sunlight. Our tested scenarios are a red light source and green light source. We will use a vase (the same for all three plants) to measure plant and root growth. In addition, we plan to measure plant color and quality. To alter the color of light, we will cover lamps with color cellophane. To ensure that the experiment is not flawed, we will use consistent amounts of potting soil and water, and grow the plants in the same vase. We will plant the grass on Friday and allow it to grow in the different light sources over the weekend. We then plan to document its growth through Wednesday.
The pictures we uploaded are of our work station. You can see the two cups under the light and the box covered in aluminum foil where we put the cups in the dark.
In the second lab, we found that the leaf chads that were moved from the light to the dark largely stayed the same (2 fell in the CO2 substance). In the light & CO2 substance, 11 rose to the surface. The H2O and light substance showed no change. Our hypothesis was partly true in that the chads required light to rise, but the chads did not all fall once put into the dark.
Our results for the first lab were that 9 leaf chads rose in the Baking Soda & light substance, one original floater fell to the bottom in the H2O and light substance, and no change occured in either dark substance. We recorded data for 25 minutes.