Light is a key component of photosynthesis. At night, photosynthesis in plants stops. You can use the floating leaf disk assay to investigate how much light is needed for photosynthesis or how the rate of photosynthesis changes with lighting conditions.
Do I have to use fresh spinach leaves? When I did this experiment none of the leaves floated up, when I left it over night still none of the leaves floated up.
Hey, so the syringe removes all the air from the air spaces in the spongy mesophyll layer. That is required for the experiment to work. If the leaf discs don’t float initially then the experiment won’t work.
If you are a K-12 student doing a school science project and you have a question about one of our projects, you can ask in the Ask an Expert forums on our website: www.sciencebuddies.org/science-fair-projects/ask-an-expert-intro
The time until the leaf disk rises to the top of the solution is a measure of how much oxygen has been produced and thus a proxy for the rate of photosynthesis. The sooner the leave floats to the top, the faster the net rate of photosynthesis.
In the experiments we performed, following the instructions in the video, all the spinach leaves in the cup with baking soda were floating within 10-20 minutes. We do have a photosynthesis lesson plan on our Science Buddies website where you can see some example results: www.sciencebuddies.org/teacher-resources/lesson-plans/photosynthesis-leaf-disk-assay.
Just a quick question. If baking soda provides CO2 to the solutions, why doesn't BTB indicator turn yellow? It stays greenish or even turns more blue? And baking soda by itself is more basic, isn't it? So how come it can be both basic and release acidic carbon Dioxide in the same time?
Although this experiment doesn't require a pH indicator, this is a good experiment to test! Acid/base chemistry is a bit more complex than one reactant or one chemical reaction product, particularly when it takes place in a solution of water. For the pH to change, there needs to be hydrogen or hydroxide ions that can be donated. Most water has a nearly neutral pH to start, and depending on what chemical reaction occurs in the solution, it can become more basic or acidic or remain neutral. In this chemical reaction, CO2 is a dissolved reactant, meaning it will be used or reduced in the solution of water by the plants over time. The baking soda dissolves in the water and provides extra CO2 for the plant to utilize.
Soap is a type of detergent that acts as a surfactant. Surfactants reduce the surface tension on the leaf's surface. This allows carbon dioxide (created from the baking soda) to reach the leaf's stomata more efficiently, allowing for more efficient photosynthesis. You can experiment with the amount of soap to test whether more or less soap is better or even needed!
The surface of the leaves is hydrophobic, which means it doesn’t like water. Thus, the bicarbonate solution can’t interact with the leaf surface. The soap molecule is a surfactant and thus has a water-loving (hydrophilic) and a water-repelling (hydrophobic) part. This allows the soap to wet the hydrophobic surface of the leaf. As a result, the bicarbonate solution can now interact with the leaf surface and can be drawn into the leaf.
Hello, thank you very much for the video. I have also reviewed the webpage regarding the science project on the impact of different factors on the photosynthetic rate. I am reaching out to you with a specific inquiry. I am planning to conduct a research project to assess the influence of dust deposition on plant leaves on the photosynthetic rate. My idea is to select random plants and manually wash the dust off some of them while leaving others unwashed. I would like to know how I can easily measure a proxy for the photosynthetic rate. I am uncertain if the method of the Floating Leaves will be effective as I suspect that the dust may be removed when I introduce the leaves into the solution. I would greatly appreciate any recommendations you can provide. Thank you!
We agree that the Floating Leaves assay will not work for your purposes because the dust is likely to be washed away. Also, there's the possibility that any changes in photosynthetic rate for things like dust deposition may be small enough that you need a very sensitive assay; Floating Leaves does not have that kind of sensitivity. We aren't experts in this area of research, so we suggest searching the literature (that's where every great scientist starts!). To help you get started, we have a resource on finding academic papers: www.sciencebuddies.org/science-fair-projects/competitions/finding-and-accessing-scientific-papers and another on how to read and understand a scientific paper: www.sciencebuddies.org/science-fair-projects/competitions/how-to-read-a-scientific-paper
The chemical composition of baking soda is NaHCO3. When it is dissolved in water, carbonic acid (H2CO3) and sodium hydroxide (NaOH) is formed. You probably noticed some fizzing when adding the baking soda to the water. This is because the formed carbonic acid rapidly converts to water (H2O) and carbon dioxide (CO2) gas. The spinach leaves need carbon dioxide (CO2) to do photosynthesis. Thus, the purpose of baking soda is to provide carbon dioxide for photosynthesis.
@ScienceBuddiesEspanol how do we know the leaf isn't just producing acid to generate co2 bubbles in a baking soda solution, rather than photosynthesis to produce o2 bubbles?
You should be able to replace the spinach leaves with other types of leaves that have a high chlorophyll content, such as kale, green collard, or green tree leaves. Chlorophyll is a key component for photosynthesis, so red or yellow leaves that don't have a lot of chlorophyll might not work well.
Hi! It sounds like you may be doing this for a science project. If so, check out our science project version for more help identifying variables etc: www.sciencebuddies.org/science-fair-projects/project-ideas/PlantBio_p053/plant-biology/photosynthesis-leaf-disk-assay A control group is usually thought of as the natural or baseline state before you start manipulating variables. When analyzing data, you can compare all other trials to the baseline to see how much effect changing the variable had. In this experiment, there is only one variable: with and without baking soda. But the baking soda is really supplying something else to the system: carbon dioxide. So, if the scientific question is "how much does the presence of carbon dioxide change the rate of photosynthesis" then the baseline would be having no carbon dioxide (meaning no baking soda). But, if you are doing a science project for school, do check out the link I put above because there are better experiments to do with this system that will result in better data to present for a science project!
Yeah, I dont know what were comparing either. I believe it might be on how photosynthesis works with and without CO2 because it says that baking soda acts as the CO2, and one cup had some, and the other didnt.
What do you do with the other 2 cups? Put them in the dark or something?
How will different light conditions affect the rate of floating leaf disks
Light is a key component of photosynthesis. At night, photosynthesis in plants stops. You can use the floating leaf disk assay to investigate how much light is needed for photosynthesis or how the rate of photosynthesis changes with lighting conditions.
Do I have to use fresh spinach leaves? When I did this experiment none of the leaves floated up, when I left it over night still none of the leaves floated up.
Yeah, fresh leaves. They have to be crisp and not wilted. If they're wilted, the cells are burst or dead and it wont work
Hello there! Nice project! Can you explain the importance of the syringe and the vacuum steps? Why did you have to do it?
Hey, so the syringe removes all the air from the air spaces in the spongy mesophyll layer. That is required for the experiment to work. If the leaf discs don’t float initially then the experiment won’t work.
What would the variables be for this project? The independent and dependent variable ?
If you are a K-12 student doing a school science project and you have a question about one of our projects, you can ask in the Ask an Expert forums on our website: www.sciencebuddies.org/science-fair-projects/ask-an-expert-intro
What could you measure to determine the rate of photosynthesis?
The time until the leaf disk rises to the top of the solution is a measure of how much oxygen has been produced and thus a proxy for the rate of photosynthesis. The sooner the leave floats to the top, the faster the net rate of photosynthesis.
How long does it usually take them to all float when using spinach? wondering how much time this would take for my lesson.
In the experiments we performed, following the instructions in the video, all the spinach leaves in the cup with baking soda were floating within 10-20 minutes. We do have a photosynthesis lesson plan on our Science Buddies website where you can see some example results: www.sciencebuddies.org/teacher-resources/lesson-plans/photosynthesis-leaf-disk-assay.
@@Science.Buddies does it nedd to use specific leaf? I pick some leaves from trees, but it can't sink
Just a quick question. If baking soda provides CO2 to the solutions, why doesn't BTB indicator turn yellow? It stays greenish or even turns more blue? And baking soda by itself is more basic, isn't it? So how come it can be both basic and release acidic carbon Dioxide in the same time?
Although this experiment doesn't require a pH indicator, this is a good experiment to test! Acid/base chemistry is a bit more complex than one reactant or one chemical reaction product, particularly when it takes place in a solution of water. For the pH to change, there needs to be hydrogen or hydroxide ions that can be donated. Most water has a nearly neutral pH to start, and depending on what chemical reaction occurs in the solution, it can become more basic or acidic or remain neutral. In this chemical reaction, CO2 is a dissolved reactant, meaning it will be used or reduced in the solution of water by the plants over time. The baking soda dissolves in the water and provides extra CO2 for the plant to utilize.
For the one put in water without baking soda,is it use water for the taking vaccum procedure
how long until you finally saw one float?
What does soap do?
Soap is a type of detergent that acts as a surfactant. Surfactants reduce the surface tension on the leaf's surface. This allows carbon dioxide (created from the baking soda) to reach the leaf's stomata more efficiently, allowing for more efficient photosynthesis. You can experiment with the amount of soap to test whether more or less soap is better or even needed!
If I dont have a hole puncher, can i just rip up a couple of small pieces?
Hi - yes, you should be able to rip or cut small pieces instead of using a hole puncher.
Can my question be "Does baking soda slow down or speed up the process of photosynthesis?"
Speed up until approximately 0.6% concentration. It starts slowing down due to osmotic stress at higher concentrations .
can i ask what does the dish soap do?
The surface of the leaves is hydrophobic, which means it doesn’t like water. Thus, the bicarbonate solution can’t interact with the leaf surface. The soap molecule is a surfactant and thus has a water-loving (hydrophilic) and a water-repelling (hydrophobic) part. This allows the soap to wet the hydrophobic surface of the leaf. As a result, the bicarbonate solution can now interact with the leaf surface and can be drawn into the leaf.
Hello, thank you very much for the video. I have also reviewed the webpage regarding the science project on the impact of different factors on the photosynthetic rate. I am reaching out to you with a specific inquiry. I am planning to conduct a research project to assess the influence of dust deposition on plant leaves on the photosynthetic rate. My idea is to select random plants and manually wash the dust off some of them while leaving others unwashed. I would like to know how I can easily measure a proxy for the photosynthetic rate. I am uncertain if the method of the Floating Leaves will be effective as I suspect that the dust may be removed when I introduce the leaves into the solution. I would greatly appreciate any recommendations you can provide. Thank you!
We agree that the Floating Leaves assay will not work for your purposes because the dust is likely to be washed away. Also, there's the possibility that any changes in photosynthetic rate for things like dust deposition may be small enough that you need a very sensitive assay; Floating Leaves does not have that kind of sensitivity. We aren't experts in this area of research, so we suggest searching the literature (that's where every great scientist starts!). To help you get started, we have a resource on finding academic papers: www.sciencebuddies.org/science-fair-projects/competitions/finding-and-accessing-scientific-papers and another on how to read and understand a scientific paper: www.sciencebuddies.org/science-fair-projects/competitions/how-to-read-a-scientific-paper
why the dish soap?
What is the purpose of the baking soda solution?
The chemical composition of baking soda is NaHCO3. When it is dissolved in water, carbonic acid (H2CO3) and sodium hydroxide (NaOH) is formed. You probably noticed some fizzing when adding the baking soda to the water. This is because the formed carbonic acid rapidly converts to water (H2O) and carbon dioxide (CO2) gas. The spinach leaves need carbon dioxide (CO2) to do photosynthesis. Thus, the purpose of baking soda is to provide carbon dioxide for photosynthesis.
@ScienceBuddiesEspanol how do we know the leaf isn't just producing acid to generate co2 bubbles in a baking soda solution, rather than photosynthesis to produce o2 bubbles?
how do we know the leaf isn't just producing acid to generate co2 bubbles in a baking soda solution, rather than photosynthesis to produce o2 bubbles?
whats the biological principal🤔🤔🤔
What can I substitute with spinach leaves
Can I use any other kind
You should be able to replace the spinach leaves with other types of leaves that have a high chlorophyll content, such as kale, green collard, or green tree leaves. Chlorophyll is a key component for photosynthesis, so red or yellow leaves that don't have a lot of chlorophyll might not work well.
what is the control group in this experiment?
Hi! It sounds like you may be doing this for a science project. If so, check out our science project version for more help identifying variables etc: www.sciencebuddies.org/science-fair-projects/project-ideas/PlantBio_p053/plant-biology/photosynthesis-leaf-disk-assay
A control group is usually thought of as the natural or baseline state before you start manipulating variables. When analyzing data, you can compare all other trials to the baseline to see how much effect changing the variable had. In this experiment, there is only one variable: with and without baking soda. But the baking soda is really supplying something else to the system: carbon dioxide. So, if the scientific question is "how much does the presence of carbon dioxide change the rate of photosynthesis" then the baseline would be having no carbon dioxide (meaning no baking soda). But, if you are doing a science project for school, do check out the link I put above because there are better experiments to do with this system that will result in better data to present for a science project!
did anyone else come from a project? oh and by the way, what are we comparing here?
Yeah, I dont know what were comparing either. I believe it might be on how photosynthesis works with and without CO2 because it says that baking soda acts as the CO2, and one cup had some, and the other didnt.
i hate science.❤
womp womp
Gyat me up
my teacher made me do this project, she didn't even talked about this yet!!! SCIENCE IS FOR NERDS!!! 😡😡😡😡😡😡😡😡
okay nobody asked
Womp womp
when did we ask?
Sounds like you need an extra English class bro 💀
Shut up and do it