to national plant biology unit three life on air so today we're going to be looking about Keithley which is foots emphasis a part that some people think quite difficult but if we just break it down into sections it's not actually too bad so let's get started so hopefully before you started national 5 you came across the sort of basic put the census equation so we're water and a calm dog say door take them to the plant and through light urging chlorophyll the plant produces oxygen and sugar option which is released so we can breathe in and sugar that's needed for the plant to have energy and to grow to survive all this is correct we have to look into a bit more detail in national 5 so to start off with this light that we've talked about being absorbed from the Sun that you've came across before plants need light that sort of thing hopefully you remember from self structure so the the first key idea of you know one that plants have chloroplasts in this chloroplast they have these little green pigments called chlorophyll and this is what is used to absorb light energy that way energy is going to be very important for airport services so it's a good starting point so let's go on to the process all for the subsystem for SAMHSA's sale is a two-stage process are you need to know the names of the stages you need to know what happens in each stage how do they relate to each other and you be able to both create unidentified diagrams of both these stages what I've done in this slide is just a brief overview of what happens each stage but they will go into a bit more detail on both the stages as well so stage one is known as light reactions that's because light energy is used extensively through stage one so basically the light from Sun is captured and the chlorophyll then convert into chemical energy in order to make ATP which is the energy required for the rest of these processes at the same time water is split in order to make hydrogen and oxygen the hydrogen from this on the 8 we'd arrest are then used in stage 2 which was known as carbon fixation fixation involves comedy oxide hence the name one of the really part of the important parts of stage 2 is the carbon fixation is a series of enzyme controlled reactions which is hydrogen and ATP from the light reactions along with carbon dioxide from the atmosphere in order to make sugar which is the end point of photosynthesis the point of photosynthesis to actually do so let's look at stage 1 no more detail so I love said the slate energy from the Sun is captured by chlorophyll which is found in the chloroplasts of plant cells is then converted into chemical energy and this is then used to generate ATP which is going to be the energy for the rest as process to take place at the same time now we have water that has taken 2 upon 3 as roots light energy is used in order to split water into hydrogen and oxygen now this is quite obvious when you think about it because the chemical formula of water is h2o so it's made up of hydrogen and oxygen this light energy is used to split the h2o into H I know this process is known this photolysis which basically just means light spotting so splitting through white energy one thing found as well is although this hydrogen is going to be used and is really important for stage 2 the oxygen is actually not required by the plant we would actually call a by-product or a waste product so the plant just diffuses the option over the cell that was into the atmosphere and that's the oxygen that we breathe so if plants decided that the action wanted to use this option there wasn't just a waste we've been all trouble that's where we get our oxygen from so in stage 2 carbon fixation this is the series of ends in controlled reactions now I really stressed the enzyme control the actions part because we'll talk about this later on in this video about how the rate of these reactions can be affected and hopefully remember something about enzymes from unit 1 and here enzymes can be affected however the hydrogen ATP from stage 1 live reactions are then combined with condo site we should just take them from the atmosphere so when you hear that plants breathe in carbon dioxide this is what before and through these reactions the sugar is produced you might come across it as glucose for natural five we just need to talk about sugar so this sugar is no meat and we always think to look at what that sugar is going to be used for so the sugar that is made by the plant has three different end points I can be used in three different ways so either the plant can use it immediately as an energy source this can be used in respiration it can make more ATP frame sort of cellular resources if you're unsure about respiration really from the don't--but respiration please go back to the end of unit one and revise over that as well if the point isn't going to use that sugar as an energy source straight away it can also store it so if you think about storing energy in humans our excess energy is stored as fat parts don't have fat though instead they have starch so these sugar molecules can join together in order to make starch so that's when you do some of these experiments in the classroom where you're testing leaves for starch you're looking to make sure the absurd energy they grow in store energy if they've created energy through photosynthesis in the first place and the fern and finally the sugar can be used as a building material in order to make the primate parts of the plant the plant grow to survive that sort of thing in this form sugar is turned into long strands of cellulose and hopefully remember that cellulose is the main carbohydrate component of cell walls so again you need to know not just that sugar is made by for some cess or Harry the sugars Maitre for the senses you need to know what that sugar can then be used for so remember and resource storage abdullah material the respiration starch and cellulose next and finally we're going to be looking at limiting factors so limiting factors means how the real four senses can be slowed down so everything holds back the read of any reaction is known as element factor in photosensors you need to know three limiting factors now there are common dots a concentration light intensity and temperature there this is something else book before it in our video you need to make sure you see these words exactly if you're asked to give a limiting factor don't just write light write light intensity temperatures faint but cannot say concentration is also wanting you to see exactly as concentration current outside that is a limiting factor if you think about this is fairly straight forward plants need carbon dioxide for Stage two full senses they need light for stage wonderful senses I need temperature because stage two is controlled by enzymes and hopefully you remember that temperature is long-term factor of enzymes activity rate we grew up to an optimum temperature but if temperatures to hide it can denature so if it's freezing cold the enzymes are not to be working that well and therefore their food sensors can be limited so once you remember what these are we're going to go through and want to attend me show you the graphs you can sometimes see in the exams Condorcet concentration again if the count outside concentration is too low rate of food since s is too low as well as Condorcet concentration increases so does reveal for december says this increases all the way up until as you can see in this graph the real force sensor starts to level off now you can see the bottom of this graph the carbon dioxide concentration is still increasing so at that point we know is no longer carbon dioxide concentration they can be the limiting factor because we're giving it plenty we're getting it more and more something else is holding back the reaction you would need to know that that hill has to be temperature or light intensity quite a common exam question if look at light intensity that's against often it's fairly basic plants need light in order to survive if you see on the graph that light intensity you can see here that as the intensity increases the rates for synthesis also increases up to a point where light intensity is still increasing but something else is holding you back that must be the temperature or carbon dioxide concentration and finally when we look at temperature later said the main part the main point of time should be a limiting factor is because of these enzymes in stage two as temperature increases the rate of foots emphasis also increases until enzymes reach to art form so just like any other enzyme reaction you will get this nice curve where the rearfoot symphysis will increase along with temperature until it hits their optimum point then it becomes denatured and the read of the action rate of activity absolute performance so really that's all there is to 2-foot sensors you need to know the two Stasia for synthesis what happens what are they called what goes on there was needed you need to know the fate of sugar units over three different ways sugar can be used and y'all seem to know the three limiting factors of photosynthesis so again I'm going to attach quizzes or or anything else on my inquest to the end of this so you can use this you can test your knowledge and hope there's pretty Tenderfoot Simpsons has been useful to you like I said is quite a hardware point of unit three okay very good salt less I know what people are asking for these for the upcoming prelims so very very slot for the prelims I'll be getting the rest these videos up as soon as possible thanks so much for listening