Hi i did a similar experiment in class and we used purple light, white light and no light. Im confused which light should be the most efficient. My experiment showed all the spinach leaves going up with purple light and none with white light. I think there could have been an error with the white light but is purple light more efficient than white light? in my hypothesis i assumed purple light would be most efficient but now I am not sure given some research says white light and others say purple light is most efficient.
Can you use filters to change the wavelength of the light reaching the leaf disks? Then I can setup an experiment with my students to exemplify which wavelengths are most optimal for photosyntehsis.
Using colored filters to change the wavelength of light reaching the leaf disks is an effective experimental setup for testing which wavelengths are most optimal for photosynthesis. Be sure to keep all other variables constant such as watts of the light bulbs, distance of the light source to the leaf disks, angle of the light source to the leaf disks, and translucency of filters for example. As a bonus, this experimental setup is nicely aligned to the AP Biology standards!
Hello! Great video by the way😊 I was wondering whether I could use temperature as my independent variable instead of light, is that possible? Thank you!
While you could use red portions of the leaves to cut the leaf discs, it is not recommended as the chlorophyll composition may differ from the green parts of the leaf and therefore, this would introduce another extraneous variable into the experiment.
It is likely not feasible to perform this experimental set-up in direct sunlight and obtain reliable results due to the fluctuations in light intensity or amount of sunlight at different times of the day. To obtain consistent results we recommend using a controlled light source (same wattage on all light bulbs) and ensuring all other variables are also controlled (distance of the light source to the beaker containing the leaf disks, same type of plant, same amount of bicarbonate etc).
The structure of the large veins makes it much more challenging to extract gasses via the vacuum mechanism rather than the flatter parts of the leaf. As the plant photosynthesizes, the gas oxygen will be produced within the leaves which will cause the leaf disks to float. Therefore, we are able to visually measure photosynthesis as the amount of floating leaf disks per minute. If we did not extract the gases from the leaves through the use of a vacuum, we would not be able to track oxygen production as a measure of photosynthesis.
A vacuum is necessary to extract the gases from the leaves. As the plant photosynthesizes, the gas oxygen will be produced within the leaves which will cause the leaf disks to float. Therefore, we are able to visually measure photosynthesis as the amount of floating leaf disks per minute. If we did not extract the gases from the leaves through the use of a vacuum, we would not be able to track oxygen production as a measure of photosynthesis.
If the vacuum doesn't work the first time, you can try again with the same leaves. However, after a few tries, the leaves would likely be damaged and we recommend starting with new disks. Adding soap is also an important step for breaking through the waxy cuticle of the plant in order to extract the oxygen.
Hi i did a similar experiment in class and we used purple light, white light and no light. Im confused which light should be the most efficient. My experiment showed all the spinach leaves going up with purple light and none with white light. I think there could have been an error with the white light but is purple light more efficient than white light? in my hypothesis i assumed purple light would be most efficient but now I am not sure given some research says white light and others say purple light is most efficient.
Can I use malabar nightshade for this experiment?
Can you use filters to change the wavelength of the light reaching the leaf disks? Then I can setup an experiment with my students to exemplify which wavelengths are most optimal for photosyntehsis.
Using colored filters to change the wavelength of light reaching the leaf disks is an effective experimental setup for testing which wavelengths are most optimal for photosynthesis. Be sure to keep all other variables constant such as watts of the light bulbs, distance of the light source to the leaf disks, angle of the light source to the leaf disks, and translucency of filters for example. As a bonus, this experimental setup is nicely aligned to the AP Biology standards!
Excellent, thanks.
Hello! Great video by the way😊 I was wondering whether I could use temperature as my independent variable instead of light, is that possible? Thank you!
Yes, a leaf disk assay can be used to measure the effect temperature has on rate of photosynthesis!
Awesome!
How many leaf disks do i need?
Also if I were to use leaves with red parts, why shouldn’t I cut leaf discs there?
While you could use red portions of the leaves to cut the leaf discs, it is not recommended as the chlorophyll composition may differ from the green parts of the leaf and therefore, this would introduce another extraneous variable into the experiment.
Can we perform this expt. In sun light
It is likely not feasible to perform this experimental set-up in direct sunlight and obtain reliable results due to the fluctuations in light intensity or amount of sunlight at different times of the day. To obtain consistent results we recommend using a controlled light source (same wattage on all light bulbs) and ensuring all other variables are also controlled (distance of the light source to the beaker containing the leaf disks, same type of plant, same amount of bicarbonate etc).
Why can’t we cut the leaves at the big veins?
The structure of the large veins makes it much more challenging to extract gasses via the vacuum mechanism rather than the flatter parts of the leaf. As the plant photosynthesizes, the gas oxygen will be produced within the leaves which will cause the leaf disks to float. Therefore, we are able to visually measure photosynthesis as the amount of floating leaf disks per minute. If we did not extract the gases from the leaves through the use of a vacuum, we would not be able to track oxygen production as a measure of photosynthesis.
But why is it harder extract gasses in areas with large veins?
Why we are creating vaccum?
A vacuum is necessary to extract the gases from the leaves. As the plant photosynthesizes, the gas oxygen will be produced within the leaves which will cause the leaf disks to float.
Therefore, we are able to visually measure photosynthesis as the amount of floating leaf disks per minute.
If we did not extract the gases from the leaves through the use of a vacuum, we would not be able to track oxygen production as a measure of photosynthesis.
@LabXchange thankyou.
what would the leaves happen if it didnt vacuum well?
If the vacuum doesn't work the first time, you can try again with the same leaves. However, after a few tries, the leaves would likely be damaged and we recommend starting with new disks. Adding soap is also an important step for breaking through the waxy cuticle of the plant in order to extract the oxygen.