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Biology question- photosynthesis

true or false?
If the light intensity is increasing and the rate of photosynthesis is also increasing light is the limiting factor?
Can you also explain why?
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mgi
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Original post by helpme2005
true or false?
If the light intensity is increasing and the rate of photosynthesis is also increasing light is the limiting factor?
Can you also explain why?

Not if the carbon dioxide concentration is decreasing for example!
Reply 2
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helpme2005
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10
Original post by mgi
Not if the carbon dioxide concentration is decreasing for example!

i thought that the rate of photosynthesis would decrease as another factor became limited. Before this point the rate of photosynthesis increased steadily with the light intensity-- at this stage is the light intensity limiting? I don't think it is but i read it online.
Original post by helpme2005
i thought that the rate of photosynthesis would decrease as another factor became limited. Before this point the rate of photosynthesis increased steadily with the light intensity-- at this stage is the light intensity limiting? I don't think it is but i read it online.


Light will increase the rate of photosynthesis till factors like co2 or humidity or temperature become limiting. The curve will flatten not decrease.
Original post by helpme2005
i thought that the rate of photosynthesis would decrease as another factor became limited. Before this point the rate of photosynthesis increased steadily with the light intensity-- at this stage is the light intensity limiting? I don't think it is but i read it online.

Yes, in that case light intensity is the limiting factor.

If something else were the limiting factor, then the rate of photosynthesis would not change as light intensity increased, because the rate would be limited by the other limiting factor.

If you increase light intensity and rate of photosynthesis increases, that means that the light intensity was the factor that was limiting the rate of photosynthesis since increasing light intensity leads to a higher rate of photosynthesis.
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helpme2005
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Original post by Sumi Shanks
Light will increase the rate of photosynthesis till factors like co2 or humidity or temperature become limiting. The curve will flatten not decrease.


Thanks so much freesciencelessons said that when the light intensity is steadily increasing and so is the rate of photosynthesis-- light is limiting before other factors are.
Reply 6
Avatar for mgi
mgi
20
Original post by helpme2005
i thought that the rate of photosynthesis would decrease as another factor became limited. Before this point the rate of photosynthesis increased steadily with the light intensity-- at this stage is the light intensity limiting? I don't think it is but i read it online.


let's not complicate things. Here is the definition of a limiting factor: "the factor that limits the reaction rate in any physiological process governed by many variables". So you could give a green plant the best light intensity known to man but if you add nearly zero or no carbon dioxide then your rate of photosynthesis is limited by the carbon dioxide concentration, not the light intensity! So the limiting factor in this example would be the carbon dioxide concentration!
Reply 7
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helpme2005
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Original post by mgi
let's not complicate things. Here is the definition of a limiting factor: "the factor that limits the reaction rate in any physiological process governed by many variables". So you could give a green plant the best light intensity known to man but if you add nearly zero or no carbon dioxide then your rate of photosynthesis is limited by the carbon dioxide concentration, not the light intensity! So the limiting factor in this example would be the carbon dioxide concentration!

thanks thats what i thought the phrase above was a quote from freesciencelessons
Reply 8
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mgi
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Original post by helpme2005
thanks thats what i thought the phrase above was a quote from freesciencelessons

ok. Always cross check your information from 2 different places to make sure you have got consistent information!.

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