sienna2266
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How is some energy that is absorbed then lost during photosynthesis?
Could someone please help with this?
BTW I understand that when it says lost it means..
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Thoth's World
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(Original post by sienna2266)
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How is some energy that is absorbed then lost during photosynthesis?
Could someone please help with this?
BTW I understand that when it says lost it means..
Attachment 734706
Hello,

Because of the facts are, I would suggest:
The plant has absorbed the energy.
Light energy has one use: photosynthesising.
Photosynthesis depends on light energy, Co2 and H20 in addition to nutrients.
One or more of these dependencies are a limiting factor.

I am not completely sure though, if you do find the certain answer please let me know
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sienna2266
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(Original post by Thoth's World)
Hello,

Because of the facts are, I would suggest:
The plant has absorbed the energy.
Light energy has one use: photosynthesising.
Photosynthesis depends on light energy, Co2 and H20 in addition to nutrients.
One or more of these dependencies are a limiting factor.

I am not completely sure though, if you do find the certain answer please let me know
I thought photosynthesis gives plants biomass because glucose which is produced is stored as biomass in the plants?so it doesn't make sense how energy is lost through photosynthesis as photosynthesis stores the energy in the plant as biomass in the form of glucose which is converted to starch to be stored?
Would definitely let you know but don't have a certain answer yet😂
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Thoth's World
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(Original post by sienna2266)
I thought photosynthesis gives plants biomass because glucose which is produced is stored as biomass in the plants?so it doesn't make sense how energy is lost through photosynthesis as photosynthesis stores the energy in the plant as biomass in the form of glucose which is converted to starch to be stored?
Would definitely let you know but don't have a certain answer yet😂
Yes you are correct. However the condition of this question states that energy is absorbed but lost. Therefore there must be a limiting factor, which is not the chloroplast conducting photosynthesis because they would not be absorbing more light energy if they were at their limiting point i.e. they cannot absorb any more light energy.

So, the only other possibilities within the photosynthesis procedure are CO2, and H20

The photosynthesis chemical reaction is
6C02 + 6H20 > C6H12O6 + 602

This is what I mean by a limiting factor. I hope that is clearer - but yes please let me know.
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macpatgh-Sheldon
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Hi boys and girls,

Let me help you to understand this Q.

When you take any "machine" (physical or biological), the efficiency with which it works (usually by conversion of one form of energy into another form) is NEVER 100%. (The point here, is not so much to do with limiting factors [which are also good to understand in a different context]. The fact that a machine is not 100% efficient means that less of the resulting type of useful energy is produced than the input energy.

EXAMPLE: When you switch on your light in your room, electric current flows through the wire from the plug, runs through the filament of the bulb and produces light energy; however, the joules of light energy produced is ALWAYS less than the joules of electrical energy that is input, because some is lost as heat, and some as UV and IR light outside the visible spectrum of 400-700 nm wavelength.

PHOTOSYNTHESIS: The choloroplast is working like a natural transducer converting light energy from the sun into chemical energy stored in glucose.

To work out the answer to your Q, look at the various stages of photosynthesis:-
Light reaction (chlorophyll absorbs a range of wavelengths of light, but only some (mainly green) ones are useful for p-synthesis, so others wasted.

The processes of production of NADPH (reduced NADP) and of ATP are also not 100% efficient.

Photosystem II -----> Photosystem II will involve loss of some energy that escapes as useless radiation.

Calvin cycle: The donation of H by NADPH may be slightly exothermic.

Carbon fixation will also involve some loss of energy, since not all the available energy in the form of ATP produced in the light reaction will be useful in making the new chemical bonds to synthesize the larger molecule C6H12O6.

Finally, some energy loss will occur during electron transfer.

I think if a Q like this was actually asked in an exam, it would be testing your knowledge of:
a) photosynthesis
b) the fact that a biomass or bioenergy diagram mostly shows reducing mass or energy, respectively, as you traverse the food chain, SIMPLY DUE TO THE INEVITABLE FACT OF INEFFICIENCY.
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Katarinanokat
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Energy is produced during photosynthesis, mainly during Photosystem II, but that energy in the form of ATP is then used for photosynthesis, thus losing energy that is produced.

Also, a lot of energy goes to reforming rubilose biphoshate such that photosynthesis is cyclic. It takes 6 turns of the Kreb's cycle to make 1 hexose sugar, so a lot of energy of photosynthesis isn't used to form hexose but rather to reform another molecule.

Thirdly, a lot of the plant energy in the form of hexose sugar is then used to help in photosynthesis, without accumulating biomass, such as active transport of ions in the roots for osmosis and a bunch of different things.

I can't see your attachment, but I'm going to assume that it says you understand that loss is the loss of energy being turned into biomass, which is done after absorption in photosynthesis in the above ways, I think?

Am I making any sense?
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Thoth's World
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(Original post by Katarinanokat)
Energy is produced during photosynthesis, mainly during Photosystem II, but that energy in the form of ATP is then used for photosynthesis, thus losing energy that is produced.

Also, a lot of energy goes to reforming rubilose biphoshate such that photosynthesis is cyclic. It takes 6 turns of the Kreb's cycle to make 1 hexose sugar, so a lot of energy of photosynthesis isn't used to form hexose but rather to reform another molecule.

Thirdly, a lot of the plant energy in the form of hexose sugar is then used to help in photosynthesis, without accumulating biomass, such as active transport of ions in the roots for osmosis and a bunch of different things.

I can't see your attachment, but I'm going to assume that it says you understand that loss is the loss of energy being turned into biomass, which is done after absorption in photosynthesis in the above ways, I think?

Am I making any sense?
I haven't learnt that much detail because I'm in AS but I think it makes sense

Energy which can be considered white light, always converts into one of our five senses for another sensation, on the micro or macro scale but the degrees varies. Once lost in an organic chemical bond it cannot be regained, in regards to the food chain because the compound never absorbs more energy after bond dissociation via digestion to reform a larger compound with more energy.

But one question, you said 'Light reaction (chlorophyll absorbs a range of wavelengths of light, but only some (mainly green) ones are useful for p-synthesis, so others wasted'. Energy is different wavelengths, some of which can appear in the visible spectrum if 300-700 nanometres.

However the colours in the visible wavelength are products of emitted wavelengths which have been absorbed then emitted by an electron. Doesn't this mean that green is not useful for the plant because it is reflected? - Can you clarify my understanding?
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Thoth's World
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(Original post by macpatelgh)
Hi boys and girls,

Let me help you to understand this Q.

When you take any "machine" (physical or biological), the efficiency with which it works (usually by conversion of one form of energy into another form) is NEVER 100%. (The point here, is not so much to do with limiting factors [which are also good to understand in a different context]. The fact that a machine is not 100% efficient means that less of the resulting type of useful energy is produced than the input energy.

EXAMPLE: When you switch on your light in your room, electric current flows through the wire from the plug, runs through the filament of the bulb and produces light energy; however, the joules of light energy produced is ALWAYS less than the joules of electrical energy that is input, because some is lost as heat, and some as UV and IR light outside the visible spectrum of 400-700 nm wavelength.

PHOTOSYNTHESIS: The choloroplast is working like a natural transducer converting light energy from the sun into chemical energy stored in glucose.

To work out the answer to your Q, look at the various stages of photosynthesis:-
Light reaction (chlorophyll absorbs a range of wavelengths of light, but only some (mainly green) ones are useful for p-synthesis, so others wasted.

The processes of production of NADPH (reduced NADP) and of ATP are also not 100% efficient.

Photosystem II -----> Photosystem II will involve loss of some energy that escapes as useless radiation.

Calvin cycle: The donation of H by NADPH may be slightly exothermic.

Carbon fixation will also involve some loss of energy, since not all the available energy in the form of ATP produced in the light reaction will be useful in making the new chemical bonds to synthesize the larger molecule C6H12O6.

Finally, some energy loss will occur during electron transfer.

I think if a Q like this was actually asked in an exam, it would be testing your knowledge of:
a) photosynthesis
b) the fact that a biomass or bioenergy diagram mostly shows reducing mass or energy, respectively, as you traverse the food chain, SIMPLY DUE TO THE INEVITABLE FACT OF INEFFICIENCY.
I actually meant to quote both of you to the reply above - thanks and sorry haha
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Katarinanokat
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I do think you're right about the green light. I take IB, so not AS or A level (so I'm taught slight variations of the same topics) but I do think red and blue light are best absorbed and green is the worst.

Honestly, even if you ignore all the specifics of the mechanisms of photosynthesis you can simplify the concept. Overall, a lot of energy is wasted (heat, radiation, etc) and other is used to sustain the plant, instead of used to accumulate biomass. As a result, in trophic levels this energy is considered 'lost' because it cannot be passed on to the consumer.

Hope that helps somehow? And maybe takes away the confusion due to the specifics of the krebs cycle and whatnot?
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macpatgh-Sheldon
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However the colours in the visible wavelength are products of emitted wavelengths which have been absorbed then emitted by an electron. Doesn't this mean that green is not useful for the plant because it is reflected? - Can you clarify my understanding?[/QUOTE]

Thank you for picking up and pointing out my error - yes, chlorophyll has a green hue because it reflects mainly green light, which stimulates principally the green cones in our retina.

Therefore, there is a dip approximately towards the green part of the visible spectrum in the chart below.

My apologies if I misled some spring chickens or physics nerds haha!


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sienna2266
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(Original post by macpatelgh)
Hi boys and girls,

Let me help you to understand this Q.

When you take any "machine" (physical or biological), the efficiency with which it works (usually by conversion of one form of energy into another form) is NEVER 100%. (The point here, is not so much to do with limiting factors [which are also good to understand in a different context]. The fact that a machine is not 100% efficient means that less of the resulting type of useful energy is produced than the input energy.

EXAMPLE: When you switch on your light in your room, electric current flows through the wire from the plug, runs through the filament of the bulb and produces light energy; however, the joules of light energy produced is ALWAYS less than the joules of electrical energy that is input, because some is lost as heat, and some as UV and IR light outside the visible spectrum of 400-700 nm wavelength.

PHOTOSYNTHESIS: The choloroplast is working like a natural transducer converting light energy from the sun into chemical energy stored in glucose.

To work out the answer to your Q, look at the various stages of photosynthesis:-
Light reaction (chlorophyll absorbs a range of wavelengths of light, but only some (mainly green) ones are useful for p-synthesis, so others wasted.

The processes of production of NADPH (reduced NADP) and of ATP are also not 100% efficient.

Photosystem II -----> Photosystem II will involve loss of some energy that escapes as useless radiation.

Calvin cycle: The donation of H by NADPH may be slightly exothermic.

Carbon fixation will also involve some loss of energy, since not all the available energy in the form of ATP produced in the light reaction will be useful in making the new chemical bonds to synthesize the larger molecule C6H12O6.

Finally, some energy loss will occur during electron transfer.

I think if a Q like this was actually asked in an exam, it would be testing your knowledge of:
a) photosynthesis
b) the fact that a biomass or bioenergy diagram mostly shows reducing mass or energy, respectively, as you traverse the food chain, SIMPLY DUE TO THE INEVITABLE FACT OF INEFFICIENCY.
Thank you
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sienna2266
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(Original post by Katarinanokat)
Energy is produced during photosynthesis, mainly during Photosystem II, but that energy in the form of ATP is then used for photosynthesis, thus losing energy that is produced.

Also, a lot of energy goes to reforming rubilose biphoshate such that photosynthesis is cyclic. It takes 6 turns of the Kreb's cycle to make 1 hexose sugar, so a lot of energy of photosynthesis isn't used to form hexose but rather to reform another molecule.

Thirdly, a lot of the plant energy in the form of hexose sugar is then used to help in photosynthesis, without accumulating biomass, such as active transport of ions in the roots for osmosis and a bunch of different things.

I can't see your attachment, but I'm going to assume that it says you understand that loss is the loss of energy being turned into biomass, which is done after absorption in photosynthesis in the above ways, I think?

Am I making any sense?
Thank you
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