Info
| Explore | We know from class that the amount of carbon dioxide increases the rate of photosynthesis. We tested our breath and baking soda as sources of carbon dioxide. We wondered if we could use different sources of co2. |
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| Research Question | What is the effect of dry ice concentration on the rate of photosynthesis? |
| Predictions | We weren't sure if the co2 in dry ice would help or harm the rate of photosynthesis in the spinach leaf disks. We were worried that the old temperatures would harm he plants. |
| Experimental Design | We used the same leaf disk procedure from the previous labs to make 4 cups. Cup 1 had no added co2, cup 2 had 3.0 grams of dry ice, cup 3 had 6.5 g of dry ice and cup 4 had 8.6 grams. We mixed hot water with each dissolved solution of dry ice so that each cup had 100 ml of water at 20 degrees... |
| Conclusion | We investigated the effect of dry ice concentration on the rate of photosynthesis in leaf disks. Bryan predicted that the leaf disks would be harmed by the dry ice. However, the data showed the opposite. The cup with the most dry ice, 8.6 g floated all their leaf disks very quickly, by 10... |
| About this Project |
Updates
Hi team,
I had a chance to check out the information in your project info section. I think you did a great job of explaining your hypotheses and comparing the results back to them! You definitely saw a large increase between your highest and your second-to-highest amounts of dry ice.
It looks like the use of hot water helped solve your temperature issue--you did a nice job of controlling the temperature variable by checking the temperature before adding the leaf disks.
I agree with you that it would be very interesting to find out what amount of dry ice would result in the maximum photosynthesis rate--i.e., adding more grams of dry ice wouldn't increase the rate any further. It would be interesting to find out how much carbon dioxide was present in each of your cups. Do you have any ideas about how you might be able to measure that? (it's not something you have to try now--but it would be interesting to learn how to do so!)
Did you have any other questions about your findings, about photosynthesis, or about science in general? I am happy to answer them!
Sincerely,
Cathy
I was just curious on why normal water without added dry ice didn't rise up until later into the time it just puzzled me any ideas?
Hi Bryan--Good question! With a normal cup of water, there's not going to be lots of carbon dioxide. There is some in the air--from respiration by lots of types of organisms (plants do respiration too)--but it is only a small percentage of our air. So without dry ice providing a source of carbon dioxide, there isn't a lot of carbon dioxide for the plants to use for photosynthesis. The amount of carbon dioxide supplied by the dry ice gives the plant a lot more carbon dioxide than normal!
You might find the following article interesting:
http://homeguides.sfgate.com/plants-grow-better-greenhouses-47175.html
It talks about, among other things, how extra carbon dioxide in a greenhouse can lead to more photosynthesis by the plant!
Hi team,
It looks like perhaps you've added the dry ice (or another form of CO2?) to the different cups, and are waiting to get the temperature of the cups up to room temperature. If you don't mind sharing, I am interested in learning a little more about what you did to problem solve with the dry ice experiment.
Hi team! How's it going this week? It looks like you might be beginning to set up your initial experiments! I am working on setting up some of my own experiments this week at my lab, with DNA. It is taking me a while to get all of my supplies assembled, but hopefully I can start my own tests soon.
An experiment our group wants to test how long it takes for leaf disks to rise if we use dry ice, but we would have to heat the water up with a hot plate
Hi, team! So it sounds like you are interested in the idea of trying out different sources of carbon dioxide--based on your first graph where you indicated that the leaf disks rose faster when you had baking soda with more CO2 present (as compared to the use of breath). I agree with you that dry ice is interesting but a little tricky, since as you add it, in addition to changing the temperature, you may have some issues with water ice chunks forming in the cup.
Do you think that there might be another way of obtaining some of the carbon dioxide from the dry ice without directly putting a chunk of dry ice in the cup at the beginning of the experiment? (Remember that for safety, we never want to put dry ice in an enclosed container). What is happening to the solid dry ice as it is sitting in a cup, for example?
For dry ice, you'll also want to connect with your teacher, since there is some additional safety equipment I would recommend--protective gloves, goggles, and possibly some tongs to use to pick up the dry ice.
I think you are off to a great start! Do you have a prediction about how well dry ice will work in the leaf disk test? Do you think it would be useful to compare to another condition (baking soda, breath, etc.)?
The light intensity affected the leaf disks and photosynthesis in the way of the cup closest to the light photosynthasised first but plateaued for the rest of the test, the second farthest away photosynthasised a little bit slower and didn't plateau, and the cup with no light did not photosynthasize.
if you put the cup closest to the light in the dark, it would no longer photosynthisize and would sink because of cellular respiration
Thanks for sharing the image from your data--it really made it easy for me to see the results of your experiment! That sounds like a good prediction that the leaf disks would sink in the dark due to cellular respiration. One thing to think about is what is being consumed in cellular respiration by the plant....oxygen in this case. One thing you might be interested in researching is why the oxygen might be forming bubbles more easily than the carbon dioxide (remember that the plant produces carbon dioxide as a byproduct of cellular respiration). What might be different, chemically, between carbon dioxide and oxygen?
Hi team--great name! I see that you have already collected some data. I really like the graph you created; the use of different colors for different curves really makes it easy to see the difference between the different treatments. I got a chance to try out this same experiment this summer and my favorite part was preparing the leaf punches in the syringe.
At the bottom of your worksheet, you mention that differences in the concentration of carbon dioxide led to different results in terms of how fast leaf disks float. What do you think might be going on inside the leaf disks during the process of photosynthesis that cause them to float?
I was also curious to know, after doing the experiment, if you had any ideas for new research questions you could test. What part of the experiment did you find most interesting?
Hello my name is Bryan
Hi, Bryan--nice to meet you!
Nice to meet you ma'am
Hello, my name is Reese and I am working with you in your group
Hi, Reese--nice to meet you!
Hello reese
Hi everyone! My name is Cathy and I am a molecular biologist...which means I love studying the insides of cells, including RNA, DNA, and protein. I have lived and worked in multiple states as a part of my work as a scientist, including WI, PA, IA, MD, and the DC area. My jobs have included working as a professor for college students, working for government research labs, and traveling around Wisconsin to teach people about biotechnology. Currently, I work for the Department of Agriculture in Ames, IA, which is also where Iowa State is located. I am also a Master Gardener and I enjoy teaching people about plants--especially growing vegetables! I am looking forward to working with you on this project. Please feel free to ask me questions as well about working as a scientist, whether it is questions about classes in college or about what it is like to work in a lab.