Chapter 13.1: The Light- Dependent & Light-Independent Stages of Photosynthesis

Hi everyone! We are slowly making progress towards the end of the entire Biology syllabus! In this video, I explain the key details in the light-dependent and light-independent (i.e. the Calvin cycle) stages of photosynthesis. I explain how light-dependent reactions are simply the photoactivation of electrons from photosystems to yield NADPH and ATP. ATP is synthesized either through cyclic or non-cyclic phosphorylation. These two products are then fed into the Calvin Cycle where carbon dioxide is added to Ribulose bisphosphate (RuBP) and the cycle produces glucose for storage in the plant.

[haenhill]

thank you doctor demi. These are really helpful. Can you please solve some more past papers 4 and 5. And also how to go about paper 5

[davidaadefolaju]

thank you dr demi, but isn't glycerate-3- phosphate formed before the ATP and NADPH is used to produce triose phosphate??

[johnmcgrath]

Me, "ohhh the P in NADPH stands for Plan-"
Dr. Demi: "The P in NADPH can be easily related to the P in photosynthesis"

[pearlofillusions]

8:51 Isn't photosystem I P-700 and photosystem II P-680.

[samx]

I have a question... During cyclic phosphorylation, the excited electrons from photosystem 1 transfer energy for the pumping of hydrogen ions from the stroma into the thylakoid space. So what causes chemiosmosis to occur? Is it the energy from the hydrogen ions that diffuse through ATP synthase or from the excited electrons from photosystem 1?

[valencia]

this helped me alot thankyou! sending love from singapore

[austinmugala]

You are the best Doc, thank you so much

[DASTAGIRMOHMAND]

Thankyou so much. U just saved my final exams

[-pp]

after the was separated 6 molecules of g3p to 1 molecule g3p, g3p making 1/2 molecule of glucose but phosphates what they will do. will they help 5 molecules g3p for the releaseing 2 inorganic phosphate and adp converting to atp

[jdegiov]

Photosystem 1 is P700 and not P680. That would be photosystem II

[NamatovuEstriana-fgpd]

Thanks for that work I have rely understood the concept

[marfizzler]

Do we need to know about TP in the Calvin cycle?

[samsyy-]

What does it mean that Photophosphorylation can either be cyclic or non cyclic? does this mean sometimes cyclic occurs and sometimes non cyclic?

[mimimulla]

Hii could u do videos on the Anslysis paper fr A2 plz ( ppr 5 )

[uroubamaheen]

Really nicely explained but just one question what is the weak reductant P680* in non cyclic phosphorylation

[teeshajairam]

I wanted to ask that we say there is mitochondria in animals and chloroplast in plants but plants also have mitochondria so do they carry out respiration in same way as we do?

[winsavierelias]

dear Dr DEMI its a new year and a new syllabus l kindly ask that you do a video on this year's sylabus you were a source last year for my as level help

[ankitasudhir]

Thank you for the video. Isn't P680 Photosystem II and P700 Photosystem I?