[Music] in this video we'll be looking at the process of photosynthesis probably one of the more important processes out there as it provides food which gives us energy and without that we really won't be able to accomplish much now the process of photosynthesis is a little bit more complicated than what we are going to look at now if you are going to further your studies and you're probably going if he's going to study something like botany you'll see that there is a bit more to this process than what we are going to do now but once again it is a basic explanation of photosynthesis so don't get too worried looking at the definition of photosynthesis you will see that it is basically this chemical equation just put into words so if you are able to recall this chemical equation you'll be able to write down the definition of photosynthesis so during the process of photosynthesis plants want to produce carbohydrates that is the food that they are going to use and that food is then in the form of glucose glucose is a carbohydrate if you recall from great teen work that you had done so you kosis then produced that is the main thing that plants want they want food but as a as this reaction takes place oxygen is formed as a by-product it just happens to form and that gets released into the into the atmosphere which is great for us so this is formed when we combine carbon dioxide and water using energy from the Sun so radiant energy from the Sun we need energy to put all of these reactants together so that we can get to the products and this can only happen in the presence of green plants so plants that contain chlorophyll the pigment that gives plants that green color and then they are also enzymes involved and we'll look at these enzymes in a bit more detail later on in the video now looking at this chemical equation this is not a balanced chemical equation so if you have physics you will know that equations have to be balanced this is just a very basic explanation so everything to the left of the error will be known as the reactants so they have to react in order to give us this tablet is not working with me today products so everything to the right of the arrow are the products that is what is formed so carbon dioxide and water are combined in the presence of radiant energy from the Sun chlorophyll and enzymes to produce glucose c6h12o6 and then oxygen is produced as a by-product so the requirements for photosynthesis everything to the left carbon dioxide water radiant energy chlorophyll and enzymes and then what is produced glucose that will eventually be stored as starch any excess glucose that is not used immediately and those are carbohydrates and then oxygen is then released into the atmosphere for a synthesis takes place in a certain part of plants and the part of the plant where photosynthesis takes place is in the chloroplast which is an organelle found inside plant cells now in great thing you would have studied some of these organelles and their functions and you would have had to draw quite a few of them and you will have to do that once again with photosynthesis and be able to draw a general structure of a chloroplast so looking at the structure of a chloroplast it's really not that hard you've got a double membrane so it's got an outer membrane and inner membrane it's that light a green section over here then you've also got the fluid fold area of the chloroplast which is known as the stroma and then the very important parts of the chloroplast are these little stacked they almost look like little stacked Smarties the thylakoids so one of these disks is known as a thylakoid and together they are known as a Granum singular and then puerile if you count all of these individual stacks is then grown up now inside these grana is the very important Plested called chlorophyll which is necessary for photosynthesis to occur in now they are also other structures that you will find in Mathura blast such as ribosomes that are scattered throughout the chloroplast mitochondria and then these starch granules so there is a bit more to it you've got the diagrams in your notes in your textbooks so just refer to those ones this is just a very basic diagram now photosynthesis getting to the process itself it occurs in two phases the light phase and in the dark face now the dark phase can be a bit confusing when you look at the name but we'll look at that in just a bit so the light phase it takes place in the presence of light so this phase you can also say is light dependent it is dependent on light for for it to be able to take place and then the dark phase it takes place in light or darkness and that is why it's called the dark phase because it does not need light it is not dependent on light so you can also say it is light independent I prefer if you use light independent and light dependent then light phase or dog phase just because it can get a bit confusing because they say dark face but it can take place during the day or without light beam prison so nighttime as well can take place in both those time now looking at the light phase it takes place in the groaner of the chloroplast so in these little stacks over here and the main reason it takes place there is because of the presence of chlorophyll in the thylakoids so the chlorophyll molecules and the thylakoids absorb the radiant energy from the Sun coming in and they are responsible for converting that radiant energy into chemical energy remember energy is never lost it is just changed into a different type of energy so what is chemical energy used for it is used in the process of photolysis which is when we split water into energy rich hydrogen atoms so we are going to do that splitting the oxygen from the hydrogen's and then it is also used in the formation of ATP it stands for adenosine triphosphate it's an energy carrier basically that is found in cells looking at the dark face it is also known as the calvin cycle very important they might not refer to the dark face they might just say calvin cycle and then you know what it is so this takes place in the stroma of the chloroplast so the fluid fold area the stroma and carbon dioxide from the atmosphere is combined with the energy rich hydrogen atoms using the energy from ATP formed in the light phase and in glucose is formed and then the excess is stored as starch so if you recall the chemical equation of photosynthesis you will see that we're going to use each one of these reactants at different stages and then we'll be forming the products at different stages for example oxygen is formed during the light phase and then glucose is formed during the dark phase and then we'll also be using water during the light phase and carbon dioxide during the dark phase now looking at what we just read let's look at this diagram hopefully it'll explain it a bit better so this yellow structure is the chloroplast so we're just looking at the different processes within the chloroplast so let's look at the light phase first obviously classified with the presence of light it is the light reactions so this takes place where in the Garona of the of the the chloroplast which you can see the thylakoid stacked here and inside them is chlorophyll that is necessary for converting that radiant energy into chemical energy so what happens is we've got water that is being sucked up from the roots of the plant and that finally reaches the chloroplast then light energy from the Sun all of this goes into the grana and there there's a reaction that occurs what's going to happen is water is going to be split using that radiant energy and we're going to have very energy rich hydrogen atoms being released and because that was released we now have oxygen that is produced as a by-product I mean that leaves the plant through the stomata and goes out into the atmosphere I'm sure you guys recall what estimator is as we've been doing that in well since grade 8 so now we need a way for this energy rich hydrogen atom to go over to the dark face into the stroma needs to be carried over there because it cannot do it itself and that is where the the enzymes now come in there is an enzyme known as in a DP and NADP functions as a taxi it is the carrier that will assist us to get energy-rich hydrogen atoms going across so the energy-rich hydrogen atoms bind to this enzyme and now it is in ADP H and that is happening over here it's going to take the hydrogen across to the Calvin cycle that occurs in the stroma but we also need energy now during this whole process there is an energy carrier known as ATP now I've got this diagram on the Left that'll show what happens so ATP stands for adenosine triphosphate so tri means three so we've got three phosphates that are bound together now at this one phosphate between the two phosphate bonds there there is basically a lot of energy between these two bonds and that is the energy which we are going to use and that is then carried across to the Calvin cycle so what's going to happen in the Calvin cycle we've now got carbon dioxide coming in from the atmosphere and that's not going to enter the stroma what we need to do is we need to get this hydrogen to combine with the carbon dioxide so that we can produce sugar glucose and that happens using the energy of ATP because we need energy to get this reaction going so what is going to happen is one of these phosphates on the left here the third one basically it's going to break off and when that breaks off all of that energy that is in between these two with the bond they have is going to be released that energy is then used to combine the carbon dioxide in into the hydrogen and basically a basic explanation you don't need to know this is that we will have something like this that is formed don't worry we don't have physics because this might be a bit complicated so this is what a carb aha it looks like and that is what we are going to get formed and that in basically stands for you can substitute any amount in this case we would substitute a six in there because we know that c6h12o6 is glucose so then we have the sugar that is formed now it's not yet the glucose that we need you don't need to know that you just need to know that in the end it is glucose that is produced but an actual fact it's something called you can abbreviate it using that it's blesser older id3 phosphate that is formed and that will then be transformed into glucose but don't worry you don't need to know that you just need to know that Lukas is formed so we now have used the ATP that ATP then becomes ADP plus a phosphate group because it's now adenosine diphosphate there's only two phosphates looking at this diagram because we've broken one off we now have ADP but this has to go back because this is a cycle remember so this ADP is going to go back as well as the nadp+ which is now dropped that hydrogen is also going to go back to the light light phase so that it can assist with the next reaction to take place so how does that ADP now again become ATP well once again with energy it takes that third phosphate and it binds it to the adenosine diphosphate and we then get ATP and this whole thing just carries on again and NADP just goes back so it can be a taxi again for the attachment of that hydrogen atom so just before I carry on to the next work have we checked everything have we used everything carbon dioxide yes that was used in the dark phase water yes that was used in the light phase that we produce glucose yes in the end of the carbon cycle we produced glucose and then yes we also produced oxygen during the light phase let's look at the importance of photosynthesis so why is photosynthesis important for our daily lives it keeps the concentration of oxygen in the atmosphere and water constant because without the process of photosynthesis we wind up have oxygen that is produced as a by-product which means that we won't have any oxygen to breathe it will also keep the concentration of carbon dioxide in the atmosphere and water constant so I remember the process of photosynthesis one of the requirements is carbon dioxide for it to occur it provides food for all hatred trophic organisms we are also here to eat rocks we cannot produce our own food like plants which are autotrophs so we need for our synthesis in order to survive and then it also makes chemical energy available for cell function so you need to know the importance of photosynthesis next we'll be looking at factors that influence the rate of photosynthesis these three of them that we'll be looking at so these factors are light intensity carbon dioxide the concentration of carbon dioxide and thin temperature so looking at light intensity that is the amount of light that is coming down on a plant so if we increase the light intensity this can also result in an increase in the rate of photosynthesis but everything has an optimal a mount that works best as soon as you post that optimal amount something will look well it's going to inhibit the process from occurring as properly as it should and it then will slow the process down so in this case if light intensity becomes too high the stomata of the plant will close which means that there's no carbon dioxide coming into the plant anymore which is a requirement for photosynthesis and carbon dioxide pain becomes a limiting factor now what is a limiting factor in biology it refers to any of the factors of variables in an environment capable of limiting the process because there's no carbon dioxide coming in it is a requirement that means that photosynthesis can take place so you'll see as the light intensity increases on this graph you'll see that the rate of photosynthesis will go up until it reaches a point or a plateau where there's too much light which means that the rate of photosynthesis will start evening out if the light intensity increases a lot more you'll even start to see a plunge in the rate of photosynthesis because the stomata have closed which means that there's no longer carbon dioxide coming in looking at the next factor it is temperature so plants photosynthesize based at 25 degrees Celsius that is the optimum temperature that they have anything lower than that it will affect the enzymes they become inactive and one of the enzymes we know that has to function during this process is nad P so that will become inactive anything higher much higher you start going to 30 plus degree Celsius enzymes will start to denature remember enzymes also if you remember from grating work have an optimum temperature at which they function at high temperatures once again so if it becomes too hot once again this tomato will close and that means that carbon dioxide will become a limiting factor so looking at this diagram this will indicate the increase in temperature to the right so as we going up up up this will probably be 25 degrees Celsius in that temperature range and as soon as it becomes hotter than that you'll see that there is a decrease in the rate of photosynthesis the next factor is carbon dioxide so when carbon dioxide is the limiting factor it leads to a decrease in the rate of photosynthesis but then also an increase will lead to an increase in the rate of photosynthesis remember if it's the limiting factor if there's more of it it means the plant can photosynthesize more because it is a requirement for photosynthesis to take place now there are a few experiments I won't be looking at the experiments in this video it's going to take too long we use the answer series book series so in their grade 11 one life sciences the experiments on page 2.4 up until 2.6 they have asked quite a few of these experiments in previous papers so just go have a look at that and then just looking at this diagram as the carbon dioxide concentration increases you'll see that there's an increase in the rate of photosynthesis but as my mom always say she says too much of a good thing is not always good so if you have too much carbon dioxide eventually you will see that there is also a plateau that occurs and the plant won't photosynthesize as efficiently as it would have I'm sure most of you know what a green ass looks like if you're my grandfather had one growing up and I liked playing in it for some reason but greenhouses are a very important play a very important role in agriculture and growing plants and that is because greenhouses actually enable us to grow plants all year round even in the coldest conditions because it is a very regulated environment now looking at the role of these optimum factors so we once again going to look at the in light intensity temperature and carbon dioxide now in greenhouses they provide optimum factors so that plants can grow optimally now looking at light intensity it accelerates photosynthesis and the growth of the plant greenhouses must allow the maximum amount of lighting so you'll see that they are transparent so that light can come in into them because without lights we don't have that energy to convert or to combine the water and the carbon dioxide and then you'll see that very serious people will have something called a photometer and that just measures the amount of light coming in and this is what it looks like in case you were just wondering you'll see that if you are interested in movies you'll see that photography these types of devices are also used to measure the amount of light so that settings can be made to the camera then the second one is optimum temperature remember plants grow optimally at a temperature of around 25 degrees Celsius or in a greenhouse that is regulated and it allows for growth all year long so in greenhouses this is a very bright basic greenhouse you'll generally see that they have flaps or basically openings and this helps to regulate the temperature because believe me in here it can get quite hot so if it gets too hot they'll be thermometers usually inside the greenhouse that will indicate the temperature the person running the greenhouse will just open the flap so that some of the air can escape and in some of them more fancy greenhouses they'll even have these flaps at the top that can open remember warm air rises cold air goes to the bottom so the warm air can escape some of them will even have like a regulation systems like a conditioner type system that will control the temperature of the greenhouse in there very big greenhouses they have all of these very sensitive sensors in them that displayed on computer screens and these days people can just regulate the circumstances of the greenhouse from their computer in an office carbon dioxide the next one so since it is a closed system carbon dioxide needs to be regulated in a greenhouse because it can't enter by itself so plants use carbon dioxide during the day and it can become a limiting factor if the plants use up all of the carbon dioxide and carbon dioxide can be regulated by using carbon dioxide tanks like yeah people can use them to pump in carbon dioxide into these greenhouses but then also you've got more natural ways of getting carbon dioxide in by using organic materials and then decomposition bacteria that will also release carbon dioxide into the greenhouse to be able to regulate that and that is the end of this video as you see it's really not that bad I think the worst part is this diagram over here but if you go through your theory and you look at this diagram you'll it'll start making sense in the end [Music]