Question

illustrate and breifly describe hoe photosystem work in the light depent reaction?

Answer 1

We know plants convert light energy into chemical energy and form sugar by the photosynthesis. this proceess initiated with the capture of sunlight in the form of photon by photosystem. so two photosystems work for the light dependent reaction which are photosystem 1 and photosystem 2. these photosystem found in thalakoid membrane of chloroplast. these photosystem contains different pigments like chlorophyll a, b carotenoids and proteins like cytochromes compounds ATP synthase.

The light dependent reaction start with PS2 by absorbing the sunlight in the form of photon throught the chlorophyl. this energy breakdown water molecule and produce 2 electrons 2 hydrogen atoms and 1 oxygen atom. the photons excited the energy level of PS2 and electron became unstable of here these electrons transferred to another molecule which participate to chain of redox reaction called electron transport chain. now these electron are moved to cytochrome b6f of PS1. in PS1 another photon absorb here and this energy is trasferred to reaction centre. this reaction centre became oxidised and send high energy electron to reduce NADP+ to NADPH. here the oxygen is produced. in PS1 cytochrome b6f and ATP synthase work together to produce ATP. this process is called photophosphorylation. two types of photophoshorylation occur one is cyclic and another is non-cyclic. The non cyclic related to cytochrome b6f use the energy produced from PS2. ATP synthase participate in phosphorylation and produce ATP.In cyclic photophosphorylation, cytochrome b6f uses the energy of electrons from both PSII and PSI to create more ATP and to stop the production of NADPH. this is a brief explanation for the how photosystem work in the light depent reaction.