how can light intensity effect the photosynthesis

correction:

Ökar ljusintensiteten hastigheten på exciterar ljusabsorberande pigment eller ökar antalet av ljusabsorberande pigment som har exciterat per tidsenhet? För att jag förstår att ljusintensiteten ökar fotosynteshastigheten? men jag hitter ingen källa som talade om hur det påverkar processen.

does increasing the light intensity increase the rate of exciting light-absorbing pigments or increase the numbers of light-absorbing pigments which has been excited per time unit?

Stephan70707 skrev:

correction:

 

does increasing the light intensity increase the rate of exciting light-absorbing pigments or increase the numbers of light-absorbing pigments which has been excited per time unit?

Both sentences are describing the same thing, but they are stated in two different ways.

1) A rate is a velocity, i.e. events per time unit (like events per second, or m/s).

2) The number of excited pigments per time unit is precisely the same - a rate!

If you consider the units (always good to keep in mind) - the respective units will be the same - compare 1) and 2).

yeah you are right if the light-absorbing pigments get excited immediately.

However, the book does not state if the light-absorbing pigments get excited immediately or gradually. if they get excited  gradually then there are different between the the rate of exciting one unit per time unite and number which can get excited per time unite.

So do the light-absorbing pigments get excited immediately or gradually?

thank you for helping :)

Stephan70707 skrev:

yeah you are right if the light-absorbing pigments get excited immediately.

However, the book does not state if the light-absorbing pigments get excited immediately or gradually. if they get excited  gradually then there are different between the the rate of exciting one unit per time unite and number which can get excited per time unite.

So do the light-absorbing pigments get excited immediately or gradually?

thank you for helping :)

The excitation of a particle, like a pigment, is an either or event. The individual particle is either in the ground state (i.e. not-excited), or it may after excitation exist in one (of perhaps several) excited states. So an individual particle is either or, it cannot be almost excited - the states are ground state or excited.

For a population of particles, this is of course different. In this case the particles can be distributed differently at a certain time point, see examples below:

1) low light level: 90% of the particles are in the ground state, 10% in the excited state

2) moderate light level: 70% of the particles are in the ground state, 30% in the excited state

3) high light level: 20% of the particles are in the ground state, 80% in the excited state

When studying e.g. light excitation events, a population of particles like your pigments are typically followed simultaneously - (pretty much) all methods used to study such excitation cannot follow individual particles, hence a population of particles are studies and all contribute.

I think you might just be a bit making things a bit too complicated. Regarding your text in bold letters and the specifics at play, this is of course dependent on exactly what is measured, e.g. "the the rate of exciting one unit per time unite" consists of several components:

*first a velocity of excitation, which is dependent on the light level, ease of excitation, concentration of the pigment, temperature etcetera.

*secondly as this velocity is measured over time, there is an accumulated effect. Meaning that if the excitation is faster than the de-excitation (the particle returns to the ground state) there will be an accumulation of excited particles as time progresses.

However such level studies, and description of such is far too complicated for the Bi2 level, it would fit in a biophysics course at University level and there discussed in greater detail.

Thank you for your generous answer 

You are welcome, glad it clarified!