NFA Courtsunis Team 4

Project by group nfacoursunisfall2016project

Info

Explore Background: The rate of photosynthesis is influenced by temperature. Spinach is known to be a cool weather crop. Spinach grows the best when temperatures range between 16 degrees C and 18 degrees C. If the temperature is too cold enzymes will mover slowly to their substrate and the reaction will...
Research Question How does temperature affect the rate of photosynthesis?
Predictions In the range from 10 degrees C to 25 degrees C, it is expected the most photosynthesis will occur around 16 degrees C.
Experimental Design What is our plan? Be sure to include enough detail that another group can replicate our experiment. What variables will we test? What variables will we measure and observe? What variables will we keep constant? How will we record our data?
Conclusion What claim can we make from our experiment? What are possible explanations for our results? How do the data we collected and our reasoning with scientific ideas support our claim? What future experiments could be done to expand on the results of this experiment?

Updates

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PlantingScience Staff
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annmarieo
said

Hello, Mrs.Holmes, we were just wondering if you can interpret the data, because it was very interesting. Especially for trial 2 when the leaf disks rose and then fell. I feel if we had a better understanding of it, the conclusion could be written better.

    Katherine Holmes
    said

    Hi Rachel and AnnMarie,

    I think the results from Trial 2 and 3 are pretty clear; leaf disks rose faster with increasing temperatures. Trial 1 is different in that only one leaf disk rose in the "hot" treatment. I'm inclined to think that either a) 35 C is not too hot for photosynthesis to occur rapidly in winter spinach leaves, or b) your water temperature for trial 1 was different. As you mentioned in your conclusion, the leaf disks may also have been damaged; but that would presumably cause them to not photosynthesize at all, and so the leaf disks in Trial 1 may have beed damaged, but not Trial 2 and 3.

    I think that you may just have not reach winter spinach's threshold for heat tolerance. One consideration is that the research you cited uses the ideal air temperature for photosynthesis, but the experiments were performed in water which has a high specific heat...that might be worth looking up.

    Another possible explanation is that you did not run the trial long enough to see the "cost" of heat. It would be interesting if you ran a trial long enough to wait for all of the leaf disks to drop again; would this happen faster in the hot water treatment, indicating faster exhaustion of photosynthetic processes?

    Those are a couple ideas you might consider when thinking more in depth about your data. I think the fact that you have a consistent pattern of increasing rate of photosynthesis with increasing temperature in trial 2 and 3 is meaningful, and you can think about what interpretation seems most likely. One key part of science is resisting the desire to fall in love with your hypothesis or prediction It is totally okay for you to find results that contradict what you expect; even if they are an artifact of your experimental design, there is often something still to be learned. 

     

annmarieo
uploaded The Effect of Temperature on the Rate of Photosynthesis.pdf in project files
Katherine Holmes
said

Hi all,

I just wanted to say thanks for sharing your research with me! I really enjoyed hearing about your literature search and reviewing your lab report. I hope you've had fun seeing the process of photosynthesis in action through your leaf disk assays; it's pretty incredible that the plants around us are building themselves out of air, sunlight, and water all the time.

Best of luck, and keep tinkering!

annmarieo
said

Hello Mrs. Holmes, I have sent a revised copy of  the lab. Please take a look at it when you have a chance, and feel free to give any advice/feedback.

    Katherine Holmes
    said

    Hi! I think your lab report looks great; you've really improved the introduction a lot. One thing I might suggest with the results is to look at not just which treatment had leaf disks rise first, but at what rate they rose. This seems particularly clear in Trial 3, where it seems like you saw all disks rise within three minutes in the hottest treatment, but a different pattern shows up in the others. There are a lot of ways to look at your data, so I think you can study it a bit more...for instance, you could also look at the percent of leaves in each treatment risen by minute 10 (your halfway point) across treatments and trials. That may lead you to some interesting conclusions. Have fun with your data! That might sound silly, but the more you dig, the more you will find. And it will help you write in-depth results and conclusions sections.

annmarieo
uploaded The Effect of Temperature on the Rate of Photosynthesis.pdf in project files
annmarieo
said

https://necsd-my.sharepoint.com/personal/ao2868_students_necsd_net/Documents/Temperature%20on%20Photosynthesis%20Lab.docx?web=1

 

Hello Mrs. Holmes this is a final rough draft of our lab. Can you take a look at it when you get the chance and give us some feedback? Thank you!

    Katherine Holmes
    said

    Hi Ann Marie,

    I'd be happy to! Unfortunately, I don't have a Microsoft account. Would you be able to put your text into a Word document for me? 

    annmarieo
    said

    i sent the lab through a PDF file. 

    Katherine Holmes
    said

    Thanks! I've attached a PDF of my suggestions.

Katherine Holmes
uploaded Lab report suggestions.pdf in project files
annmarieo
uploaded Temperature on Photosynthesis Lab.pdf in project files
annmarieo
said

Hello Mrs. Holmes, we ran our last experiment today. It was interesting because, for trial two and three, the leaf disks in the hottest temperature (35C) rose before the leaf disks in the optimal temperature (16C-18C) did. But in the first trial the leaf disks in the optimal temperature rose and the ones at 35C barely rose. 

    Katherine Holmes
    said

    Hi Ann Marie!

    That is pretty interesting; do you have an idea of why you saw differences between trials? There can always be variation between trials that is more related to your experimental setup than the question you want to answer - that's why it's so good to get multiple samples of data, called replicates. Sometimes leaf damage can alter the action of photosynthesis. Was your expectation that the leaf disks would rise first in the optimal temperature?

    Thanks for keeping me updated! I'm interested to learn about your conclusions.

    annmarieo
    said

    Yes, we expected the most photosynthesis to occur at the optimal temperature. 

Christine Courtsunis
said

Hi Katie,

The students did practice the spinach leaf disk assay. I think we have figured out a way to keep temperatures constant for that treatment. They would be measuring the rate of photosynthesis the same way we did with the bicarbonate experiment by measuring the rate. The time at which 50% rise. Then continue on until all leaf disks rise if they want to. 

Ann Marie;s article has the  temp at 60-650F  or 16-180C. It was an article from a gardening journal. We were hoping to find a little better source for the hypothesis. Another group found an article at 250C. At this point, I am curious. 

I will be getting the spinach, true winter spinach, from my brother in law an organic vegetable farmer on Wednesday night. He said it is true winter spinach and he will have the name of the variety for me. The spinach is not baby baby, or adult. He called it "teenage spinach."

I hope this helps. I honestly have not figured out how to use this forum and we are progressing along. Thanks for your help. 

Chris  

    Katherine Holmes
    said

    Hi Chris,

    Thanks for getting back to me! My apologies for being a little late with my replies. The last week has been crazy but I should be able to check daily from now on.

    One of the papers I've uploaded seems to agree with your gardening journal article; it lists some "cool climate" herbs as performing best at 17C, and one of those is Chenopodium album, a plant in the same family as spinach (Amaranthaceae). That's from the "heat stress" PDF.

    Okay, great to hear they should be able to measure photosynthetic rate with the tools from the leaf disk assay. This is my first time on PlantingScience, so thanks for your patience with my questions!

    Katie

Katherine Holmes
uploaded PlantingScience-C3photosynthesisPDF.pdf and 2 more files in project files
annmarieo
said

I ended up printing different ones, with similar information at school. But, can you take a look at my background and see if there are any corrections needed, or anything to be added to it? 

Background: The rate of photosynthesis is influenced by temperature. Spinach is known to be a cool weather crop. Spinach grows the best when temperatures range between 16oC and 18oC.1 If the temperature is too cold enzymes will mover slowly to their substrate and the reaction will occur slower.
Although spinach has a cold tolerance, light and CO2 are required during exposure to low temperature in order to attain maximum cold tolerance.2 Usually the higher the temperature, the greater the rate of photosynthesis (due to increased collisions with enzyme and substrate). However, if the temperature is too high, the rate of photosynthesis can decrease. Enzymes involved are sensitive and can denature the  active site, which can inhibit proteins' ability to work. CO2 fixation decreases by moderately high temperature stress. The decrease CO2 from inorganic compounds to organic compounds is associated with the inhibition of activation of rubisco.3 Photosynthetic II is the primary site of heat damage to the photosynthetic function. Although, it has been reported that dephosphorylation of PSII in response to heat stress can be considered as a protective mechanism, where the repair process of PSII is done. Overall, adding too much heat to spinach leaves will kill them because it will not be able to perform photosynthesis. Lowering the temperature too much will also kill process of photosynthesis.

From the articles I've found, I formulated this hypothesis. 

Hypothesis: In the range from 10oC to 25oC, it is expected the most photosynthesis will occur at around 16oC. 

The hypothesis still needs work, because another group found the optimal temperature around 25oC, but I found from 16oC-18oC.

 

    Katherine Holmes
    said

    Hi AnnMarie,

    I think your background sounds great! My main suggestion for your background is that you be a little more specific when you use the terms enzyme and substrate. Which part of photosynthesis are you referring to? And what type of proteins are you talking about (the light-harvesting protein complex)? If you put those terms in a more specific context, it will be easier to follow your logic. 

    It's perfectly okay for your hypothesis to be different from another group. What's more important is the reasoning behind your hypothesis - if you found good evidence in the literature for similar crops doing well at 16C, that's valid. 25C actually sounds a bit warm to me for a winter crop, since that's 77 Fahrenheit.

    I found a couple papers that you may or may not have printed already, and I'll attach those. One of them discusses the effects of both light and temperature on photosystem II activity.

    Thanks for keeping me updated!

    Katie

annmarieo
updated the project info
Christine Courtsunis
said

Ann Marie, The highlighted word I think should be photosystem. 

annmarieo
said

Hello Mrs. Holmes, so we are just going to stick with winter spinach leaves. Also, do you think you can find any articles on the affect temperature has on photosynthesis on spinach leaves, i am still having trouble finding some. Most that i am interested in i have to buy it to read the whole article. 

    Katherine Holmes
    said

    Hi AnnMarie!

    Could you send me the authors, publication year, and journal names for the articles you found? I may be able to find and upload those files for you. I'll dig around and upload a couple more that I find.

annmarieo
said

We're setting up the experiment with placing water and the spinach leaves, and a thermometer inside plastic cups and then surrounding it with styrofoam to ensure the temperature is constant. Placing it in temperatures below 60 degrees F, above 65 degrees F and between 60 and 65. (i found that spinach leaves grow best between 60 and 65 degrees F)

How do you suggest we measure the rate of photosynthesis? Maybe with an indicator to see how much glucose was produced, or something to measure how much oxygen was produced? or any other idea. 

Katherine Holmes
said

P.S. It would be good to look up any tips for the search engine you use. E.g. some search engines will let you use * to shorten words and search for more matches. So if you search for "cucurbit*", you will get back results for both "cucurbit(s)" and "cucurbitaceae." In general, start with fewer key terms (not sentences) and add more words when you need to refine your search.

Katherine Holmes
said

Hi AnnMarie!

That's really interesting - when you say winter/summer spinach leaves, are you referring to two different varieties of spinach, or just the time at which a single variety is grown?

I would head to Google Scholar to look up the effect of temperature on photosynthesis at the broadest level (all plants) first. Your instructor also mentioned that you have access to the NY state Gale databases; is that through your library? In either case, it would be good to use keywords such as "photosynthesis" and "temperature." Sort your results by "most cited" and you should get the most broadly-applicable and easy to understand scientific papers. You may not be able to find a study on spinach, but that's okay.

If you would like to learn more about how spinach in particular photosynthesizes, you could perform a separate Google Scholar search with "photosynthesis", "temperature", and "spinach." However, you're likely to get more information if you look up what kind of vegetable spinach is. For instance, squash, watermelon, and cucumbers are all "cucurbits," in the scientific family Cucurbitaceae. Plant families end in "aceae." If you find the right plant family for spinach, and perform a search using that word (e.g. "cucurbitaceae"), you should be able to find some papers that use vegetables that have a close evolutionary relationship to spinach, and presumably share some traits with spinach that affect its photosynthetic response to temperature. You can make some predictions about your project based on those studies, and your more general literature search of photosynthesis and temperature.

If you do have different varieties of winter and summer spinach, you might want to look up what the plant breeders did to make those varieties "summer" versus "winter" using Google Scholar.

Hope that helps! Let me know if you need me to clarify anything.

annmarieo
said

Also, do you know where we can find any articles on the affect temperature has on photosynthesis in winter/summer spinach leaves?

annmarieo
said

Hello Mrs. Holmes, for our experiment on, we are trying to determine the affect temperature has on the rate of photosynthesis in winter/summer spinach leaves. 

Katherine Holmes
said

Hi Rachel and AnnMarie,

 

It's so nice to meet you! Apologies for the delayed response. I'm really looking forward to helping you navigate your project. Rachel, my sister is a veterinary technician and a dog trainer, and it is really cool to see her work with animals. AnnMarie, I also used to dance ballet...but not very well Luckily I'm still in a field (Ecology) where the community of scientists loves moving around and getting outside. I am a graduate student at Cornell, and am studying natural plant-insect communities, including how plants use toxins to defend themselves against insect herbivores. I'm particularly interested in how plants try to both outgrow each other in crowded fields - for resources such as sunlight! - and produce hard-to-make toxic compounds at the same time. Previous research suggests doing both is not easy. Since photosynthesis is such a fundamental process, I'm looking forward to hearing more about your project. I think it's easy for all of us to take it for granted, but the ability of plants to harness air, water, and sunlight to "build" themselves is so essential to life - after all, plants are the foundation for our food chain. Looking forward to learning more about your project,

 

Katie

Devesh Shukla
said

Hello Guys,

I am Dr. Devesh Shukla, working as a Liaison to coordinate between you and your mentor, and teacher. I am pleased to see your activities in school.  Katherine Holmes will be your mentor for this group project. She will guide you through this exciting science quest "Power of Sunlight."

Best

Devesh

Katherine Holmes
joined the project
    Devesh Shukla
    said

    Dear Katherine Holmes,

    Thanks for your support and willingness to mentor these budding scientist. Could you please introduce yourself so that the conversation may be rolling on further.

    Devesh

PlantingScience Staff
joined the project