welcome biologists in this session we're going to take a look at spec point e and f which is looking basically at the light independent stage of photosynthesis now this occurs within the stroma inside the chloroplast and don't forget we've got from the products of the light dependent reaction we have the products we have nadph we also have atp from the light dependent reaction now they're going to be using the light independent reaction now how this works is first of all i have a five carbon compound called iubp an iubp is bound to carbon dioxide which comes into the plant through the stomata it diffuses through the stomata so my carbon dioxide combines with my iubp to form two lots of gp now this uses an enzyme called rubisco to do this so therefore um my my carbon being attached from iubp um is circumstantial to um that enzyme working at its optimum and that enzyme is actually quite a very poor enzyme but it will still be impacted by things like temperature now this process is called carbon fixation where the carbon from a carbon dioxide is fixed into my iubp to make two lots of gp which are a three carbon compound now my gp is then converted into tp and this is by um my hydrogen ion and my electron from my nadph this has come from my light dependent reaction my electron and my hydrogen are going to be moved on to my gp so if my gp is gaining a hydrogen and electron it has been reduced so my gp is being reduced and it's also going to be phosphorylated because my gp is going to gain an inorganic phosphate from atp and so therefore this means that i'm going to get an adp this can then go back to my light light dependent stage to pick up another hydrogen ion and also an electron and i'm left with adp and again this can be phosphorylated back into atp using atp synthase from a light dependent stage so after my gp has been phosphorylated and reduced to make my two lots of gp again that's a three carbon compound i get what's known as product regeneration and what happens here is out of my so i've got two lots of gp sorry tp which are three carbon compound so i've got six carbons in total now what happens is one of those carbons comes off and it makes some kind of a product now that product could be something like um glucose it could make up starch it could make up um cellulose it could make up um a non-carbohydrate-based sauce such as it could make a lipid or it could make a an amino acid so one of those carbons is removed and then i'm left with five in total so i get iubp being regenerated and that is the light dependent independent reaction which occurs within the stroma and that is pretty much everything that we need to know now we need to use this terminology when we're talking about the light independent stage which is also known as the calvin cycle and that is everything you need to know guys good luck with your exam