wacha chilli Welcome again class to this class where by today we were going to discuss about photosynthesis you remember the previous class we discussed about Hadir'a this class and about the foundess or an adaptions or an Hadir'a So in today's class we are going to discuss about photosynthesis Let's begin first of all by looking at the requirements of photosynthesis so the requirements of photosynthesis we have lights we have water and then we have finally we have chlorophyll. So these are the basic requirements for photosynthesis. So photosynthesis may be summarized by the equation whereby we react carbon for oxide, we react it by water, then we get simple sugar or glucose plus oxygen. So for this process to take place, there must be chlorophyll and there must be light. So photosynthesis proceeds in two stages, whereby the first stage is the light stage, whereby the light stage might be also called light dependent stage. At the other stage we have the dark stage, which might be called light independent stage, it does not need light. So let's look at the light stage of photosynthesis. So what happens in the light stage? So the main process in light stage, we will see is photolysis. So what is photolysis? This is the process where the sunlight breaks down water molecules to hydrogen atoms and oxygen gas. So it must be hydrogen atoms not hydrogen gas. So the hydrogen atom rather is preserved in the stroma for the dark stage or the light independent stage, while the oxygen molecule, the effuses out of the chloroplast, it will live out of the stroma. So the other aspect is that some of the sunlight is preserved in the grana. The chlorophyll absorbs some of the sunlight, so as to be able to manufacture the energy plant, that energy is called adenosine triphosphate ATP. Now this ATP is stored for the light independent stage, which is now the dark stage. Now having done with the light stage, let's proceed now to the dark stage. So what is the dark stage? So the dark stage of photosynthesis, this is also called the light independent stage. It happens whereby there is no light or there is no sunlight in short. So the light independent stage, which is the dark stage, there is a main process that happens, which is called carbon dioxide fixation. So in the carbon dioxide fixation, the hydrogen that was preserved in the light stage, reacts with the carbon dioxide to form simple sugar and water molecules plus energy. Now in the morning, I know maybe you have ever worked in, maybe in the field, and then you saw that there are some dew, or there are some water in the plants. Now this is where the water comes from, in the dark stage of photosynthesis. Now in the dark stage of photosynthesis again, now some of the sugar molecules is being stored by the plant in form of starch, or in some it's transported to the other parts of the plant, in form of, in form of sucrose. Now let's look at the factors affecting photosynthesis. So we have different factors affecting photosynthesis, let's begin with the light intensity. So if light is available, photosynthesis will proceed at a rapid state, or we might say that the more the light intensity, the more the rate of photosynthesis up to a certain point, and then its levels off. Now here, the temperatures and the moisture content is the constant factor. Now the next one, let's look at water. So the more the water in the environment, the more the plants will photosynthesis. This is because the water will make the plant cells to be charged, thereby the leaves will be exposed to the environment accordingly. They are by sunlight to heat, the leaves, photolysis will take place, and then photosynthesis will proceed from them. Then the other factor we look at is temperature. So the higher the temperature, the higher the rate of photosynthesis, but temperature only affects the dark stage of photosynthesis and not the light stage of photosynthesis. So on elevated temperatures, the rate of photosynthesis will be elevated up to a certain point, and then it will start to decrease until it declines completely. This is because the dark stage of photosynthesis is enzyme controlled, and since it is enzyme controlled, what happens is that enzymes are denatured on very high temperatures. And that's why the rate of photosynthesis will rise up to a certain point, and then it will stop on increased temperatures. So the last factor we look at, let's look at the carbon-foxine concentration. So the more the carbon-foxide in the environment, the more the plant will photosynthesize. This is because there will be excess CO2 in the environment, so as to be able to form simple shruga with the hydrogen that was formed in the light stage. So, but the rate of photosynthesis takes place or happens up to a certain point on levels of carbon dioxide. This is because temperature is a light, is a limiting factor here. Now, in the next classes, we are going to look at something different, and I hope to meet next time, and I hope that again, consigning photosynthesis, we are now good. So, let's meet on the next class.