Science Buddies: "Ask an Expert"

Hi
I'm working on my Science Fair project and I am wondering about doing the floating leaf assay experiment. I would like to try and make it an experiment though that relates to water quality. Would something like adding something sulphur or nitrogen based to the water that the disks are floating in make a difference to the rate of photosynthesis or would this have little impact?
There is a lot of talk around at the moment about how farming practices affect water quality and I would like to design an experiment around the effects of this. Thank you for your time.

And just addition to my question - would sodium affect the rate of photosynthesis?

Georgette

Moderator note: Hi Georgette, I combined your 2 posts - and removed your second post, that way, the experts can see that they need to respond to your post. Thanks!

Hi Georgette,

I hope you're having a great day! You have some interesting ideas related to the Floating Leaf Assay Experiment and I like how you want to make your project related to water quality! As you said, that is a very hot topic and it is also very important.

Nitrogen and sulfur (as well as other gases) do affect the rate of photosynthesis (references: https://www.nature.com/articles/s41598-018-20653-1; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6018418/). The interactions between the gases also contributes to the rate and efficiency of photosynthesis. While I am not sure about the direct effects of adding these gases for this project, I think it would be interesting to simulate different environmental conditions and examine how they affect the rate of photosynthesis.

To answer your second question: salt stress (either an addition or depletion of sodium) would absolutely affect the rate of photosynthesis. Significantly changing the concentration of salt will affect the Na/K balance, which is incredibly important for photosynthesis. This paper (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633845/) is a little dated, but I believe it is still insightful.

I hope I have answered your questions! Please feel free to reply on this forum should you have any more questions/concerns! Good luck on your project!

--Brandi

Thank you so much for your advice.

If I add salt in different amounts to the water and baking soda solution for the leaf assay experiment, is this "good science"? Will the results be valid and reliable or could there potentially be a reaction between the salt and baking soda that would distort the results?

Thank you again

Thank you for your questions! There is no chemical reaction between sodium chloride (salt) and sodium bicarbonate (baking soda) when these two reagents are put together in solution. There shouldn't be any distortion of the data due to the salt or baking soda in solution.

"Good science" refers to following the scientific method (i.e. inquiring, formulating a hypothesis, gathering data, and interpreting your results) and not necessarily on the quality of the data. I think your experiment follows "good science" and is a good model for a real-life process. Just make sure you stick to the procedure, run controls, and replicate your experiment more than once. Then, be sure that your interpretations of your results are based on what actually happened and not what you hypothesized/expected to happen.

I hope this helps answer your questions! Feel free to reply if any more questions/concerns come up!

--Brandi