Elinda, are you there? Yeah, my wife I is today. Okay, keep the camera off then how are you? Good. Are you still traveling? Yeah, I'm going back to Singapore next week. So are you with your grandparents? Yeah. Have you had a nice time? Yeah, good. What's the best thing that you've done? We went. To like this. Oh, I'm losing your sound. Can you hear me, Linda? All well, I'm going to start marking your homework. I'm not sure whether you can hear me or not, but I'm going to make a start because your sound keeps breaking up. I can hear you now. Okay. Yeah, good. I think you're coming in and out. I heard a little bit of what you said, but then you just disappeared. So we'll just get started with this. I predict that. So this was the photosynthesis experiment last lesson. We talked about why starch is stored in plants, because some students can get a little bit confused with that, because it's glucose produced in the photosynthesis equation. So they get a bit confused why starch is suddenly involved. So we had two leaves, one which had been left for a few days in the dark, obviously still attached to its plant, or it would have died. So you put the whole plant in the dark for a few days, and then your second plant is just left in the sunlight. Prediction that the leaf exposed to the most sunlight will have more starch. Variables amount of sunlight, presence of starch. Yeah, same type of plant. Same amount of substance says that's good. Putting that back on the chat. Okay, method. So if we are using iodine to test for starch, it's not going to work if we don't get rid of the Green pigment chlorophyll, because we will not be able to see the colchange properly. So the first step is we immerse the leaf in boiling water to soften it, to remove the waxy cuticle and to start to break down the cell walls. So tweezers, peka and boiling water. Then we place the leaf into the ethanol in a test tube, being very careful, because the ethanol will boil at a lower temperature than water. So even if the water is no longer boiling, your ethanol will probably start boiling. So you need to be aware and point that away from yourself. Then we take the leaf out and we give it another little wash in the water to wash off the ethanol we drop on some iodine solution. Now, this isn't a watch class. It doesn't matter. It could be a watch class. That wouldn't be a problem to use a watch class. It is a Petri dish. So this is the type of dish that you usually take a bacterial sample of, and it's got a lid and there be some special jelly inside that the bacteria can grow on. So this is just one half of a Petri dish. And that's a White tail. Putting that on the chat. So why does this one look a Brown collinda? Like it doesn't change. So we're just seeing the color Yeah, we're just seeing the color of the iodine, aren't we? So the iodine doesn't change. The leaf itself should be pretty White now because we've taken away the chlorophyll. So the leaf will just stay a whey color and we'll just see the Brown iodine. And then this one, maybe we'll just add a little bit of what's that strange thing? Oh, there's a new color slider. Never seen this before. So on the colors, there's a slider where you can completely choose your color. Now that's too black. Let's get a bit bluy. Okay. So I'm just going to add a little bit of blue to that because we say iodine turns blue black in the presence of starch. Conclusion so explain how sun, explain how exposure to the sun affects the amount of starch produced by the leaf, sunlight is important for plants to make starch part of the ther exposed to more sunlight than black. Okay. Right now you didn't have a huge amount of room there, but you needed to explain why the leaf with less sun exposure didn't have any starch. You needed to talk about starch is made when there is excess glucose. Therefore, if a plan has been left in the dark for a few days and unable to photosynthesize, it will use up it's starch stores. So we needed just a little mention here of the fact that it's actually glucose used, produced in photosynthesis. Be careful saying that starch is produced. Okay, Linda. So today, we are looking at structure of the leaf. And let's get our sources. Can you read this place? Learning objective to understand how the structure of belief is related to its function, to identify different structures of relief, to describe the function of different structures of relief, to explain how leaves are adapted to adapted from photosynsis. And what can you see in the background there in the picture? I'm hard to believe. And what are the parts that are a little bit like they're glowing? What are those parts alpper epideris? How about these ones? Highly said cells. Not quite, but don't worry, by the end of the lesson, you should be more familiar with what they are. So we'll leave that until we've studied the diagrams a little bit more. So we have got four plants looking quite different. What are the differences and what might have happened to cause these differences? I'll give you the pen in case you want to Yeah, that's the pen in case you want to circle something that you're talking about. The right one is like when it first started to grow. The second one is like when it fully grown like on the top left, then the top right one is like during autumn when like it turns yellow orangey. And then the bottom there is like there's no way color and the plant like basically died. So you are talking a little bit as though this is the life cycle of one plant. This is four different plants grown in different conditions. And some of these plants have got problems. So let's start with this one. What's the problem with this plant? It shouldn't be yellow. It doesn't have end of chlorophyll, absolutely. And we'll look a little bit in later lessons as to what nutrient deficiencies can cause lack of chlorophyll. Yeah so this plant does not have enough chlorophyll, so it's going yellow in color. Now you might see that happen in your house plants if you don't give them any fertilizer, if they run out the nutrients needed to make chlorophyll. How about this one? Any problems with this one? So that's looking pretty good, isn't it? And then watch about this one here. The roots look okay. They look the same. It's too short. What might it be lacking? Glucose. Why would it be lacking glucose? Because it doesn't have enough energy. Okay. And what about this one? Look at what's happening to the leaves. The leaves look a little bit floppy, but could make them get floppy like that, wilting. Too much less water, okay, possibly lacking water. So let's see what the notes say. So the first one, healthy plants, access to all the resources. Second one, yellow leaves. So it can't make chlorophyll. Now if it can't make chlorophyll, it won't be able to photosynthesize properly. So eventually this plant is going to die. Wilted leaves, not enough water. It is small and hasn't grown well. So it may not have had all the resources it needed to photosynthesize effectively. You said not enough glucose, and that would be a result of not being able to photosynthesize effectively. Maybe it's in a very dark place. It's not getting enough light. Okay, remind me of the photosynthesis equation. Linda, what's the photosynthesis equation? Oh, water. Carbon dioxide way and wait water plus oxygen. What? Wait, carbon. Dididixixide and water, basically glucose and oxygen. And what do you sometimes see written above or below the arrow light? And and sometimes you'll see the word chlorophyll. It's not in any of these, but you may see it in some textbooks. Yes, a carbon dioxide. Always remember that plants help us by producing oxygen. So they need to produce it. So it needs to be on the right hand side of the equation. So if plants don't get enough carbon dioxide or water or sunlight, they cannot photosynthesize effectively. So how do they make sure that they get enough of these things by adaptations? Linda, can you hear me properly, or am I breaking up for you? It's okay, but sometime I disconnect. Yeah, okay. We'll just Carry on. There's nothing else we can do. So adaptations is usually a topic that you will study when you're doing ecology. You will look at adaptations of Arctic animals or desert plants or animals. But a plant itself to stay basic plant, not any specialized plis itself, very, very specialized. Its leaf is highly adapted for its function. So here's a couple of adaptations that are quite often studied. Plants have to photosynthesize to survive. Therefore, they have got a lot of adaptations to help them do this efficiently. And here we are. We have got a cross section of a leaf, and it's quite complicated. And all of the different structures have got different jobs. Now what we're going to do, especially because we're breaking up a little bit. We are going to do a little research activity so that we don't have to do too much talking today. A. So I'm going to put. A table up. Right. I'm going to cut it out because it's easier for you to type when it's cut out. First one. And then much like we did with the food groups, I'm going to put an information sheet up or this first structure here, I'm going to get you to name it. And then I'm going to ask you to describe it and talk about its function. Okay, this the first one. Can you move things around on the screen as you need to, Linda? If something's in the way, can you move it? Okay. Yeah, brilliant. Okay, start with that one, then fill out the first section. Good. Okay. Right next one. Can you read the page down a bit? Yep. Pick out. Ready for the next one? Yeah. Yeah, I'm not sure why they don't allow a slightly smaller font. It's just a little bit bigger, isn't it? Yeah. They will eventually, when they add a tick and across. All right, what have we got next? Okay. And last one. Oh, there we are. Alright, let's just see if we can get this one to fit on a bit better. I the wrong one there. Hey, God. Right. I'm going to put this onto the chat. And to give you a break from writing, hopefully you're going to be able to talk to me without me losing you too much. Let's get rid of those. We've got them on the chat saved. So I'm going to get another sheet and let's see what you can remember. But I don't need you to write anything for this one, so you can just talk me through it. There we go. Now you're going to need to kind of circle or point to where you are. Alright so you've got the pen. So for example if you're going to start and start wherever you like and start down here if you want, if you're gonna to start down here you can circle it so I know what you're talking about so I want you to tell me the name of the parts and I want you to tell me it's function, what it has got to do with photosynthesis. Hey Linda, see what you can remember? This is the quxy key to cool. It's like a transparent waterproof layer that protecchecand leaves. Why is it transparent? Let sunlight through good, protect the leaf from what? Too much sunlight Yeah and it also helps to protect the leaf from insects. Now some insects can still munch their way through the waxy cuticle, but there will be some that cannot penetrate it, so it does offer some protection against being eaten. Right? Brilliant. What's next? This yes palace and massive field Yeah palisade mesophyl. It is like upsell and it like it's where photosynses take place. So what has it got to enable photosynthesis to take place and chloroplalots and lots of chloroplasts? Yeah large surface area packed tightly together. So there's no air spaces in that layer, is there? So they're like building bricks or squashed tightly together to get a maximum surface area for the absorption of the sunlight. This is spongy. Mm. Hm, it allowed thoughts to diffuse through the ef allows what? Sorry, to diffuse gases? What gases like oxygen and carbon dioxide? Good. Is there any photosynthesis happening here? No, looks like there's still chloroplasts. Yes, a bit. But of course you're getting lower down into the leaf. So the sunlight will not be able to penetrate that far as effectively, but there will still be a bit of photosynthesis happening. Okay, what else? And we can also say that these are a different shape, aren't they, from the palisade cells? Yeah, Yep. What's next? This is the. I missed the first bit of that. Say that again, dithem and flow em Yeah and together we call this a vascular bundle. A vascular bundle containing the xylem and the flowem. What can you tell me about the xylem and the flowem? It's Dido M. I think it like transport, sports, water and mineral. Yeah upwards from the roots. The other one, the flow and transport. Blue. Cut all around the plant wherever it's needed, all the way down to the roots as well, of course, because they need glucose for respiration, for energy. This is air spaces. It's like where the oxygen and carbon dioxide go into or out of the cell. Yet remember, sometimes oxygen will be going into the cell when the cell is carrying out respiration, because these cells are going to need energy for the processes, all of the life processes that are going on inside them. So it's not always just going to be photosynthesizing. Sometimes it will be respiring as well. So there's a balance. We'll come on to respiration next. This is the stoma. What's the plural? No matter. Yeah. Allow gas exchange cut and water to leave the leaf. Okay. This. To open and let the gas in or close to like don't. Now why are these stomata found on the bottom of a leaf and not on the top of a leaf? His water can't leave the lay from the top Yeah so the plant doesn't really want to lose water. However, that will happen when the stomata opens. So there's a little bit of a balance they've got to balance needing the gases to diffuse in and out with trying to prevent too much water from being lost. So by being on the underside of the leaf, it's obviously shadier and an awful lot cooler. So less evaporation is going to happen. Now I'm just going to show you a picture. Let's find it. Now you might do this experiment at school. So basically what you do is you get a leaf and some clear nail varnish, and you paint the undersurface, the underside of the leaf, with your clear il nail varnish, let it dry, peel it off, and then look at it under a microscope and you can see the stomata. You might also be asked to calculate how many stomata there are in a certain area. So that might be something that you do and sort of thing that you are looking for. Oh, let's see if I can get that on. Now. Obviously, this is super, super magnified. It wouldn't look like that in the classroom. Yours will look more. Like this, if you're lucky. The best tomata. And let's see if I can get you one. Yeah. And this one has got some kind of grid. I don't know whether you can just see the outline of these little squares. So this is an overlay Yeah so this is an overlay that you can pop onto your glass slide, which will give you a scale. And then you can count your stomata and then you can calculate up times mes it up. Alright, so that's what it look like if you do do this experiment itlook like this one, if you had a better microscope, it will look like this. And then this final one is a 3D scanning microscope. So you definitely will not see something like that in a lab, not at school. All right, let's go back to this one. So in a minute, I'm going to get you to do a practice exam question to whiz through these, right? So this is just showing you the difference here. Sometimes you will see a 2D cross section. Sometimes you'll see a 3D. So you need to make sure that you are familiar with both of them. Okay okay. And you need to be able to describe the adaptations, the different parts, and we've done that verbally. That's fine. Here's another cross section again. Now this is important. This is a couple of things that we haven't mentioned. So thinking more about the leaf itself as a whole, leaves have got large surface areas to absorb maximum sunlight. In fact, if you think about a tropical rainforest, if you've got a plant that is in a lower part of the canopy, it will have even bigger leaves than one higher up, because it's adapted to absorb as much sunlight as possible. So the bigger the leaf, the more sunlight it can absorb. And they are also thin. And that is so that the gases have got a shorter distance for gas exchange, for diffusion. Who? I'm not sure why this is telling us the answers. What would happen if there were not enough airspaces, right? Why wouldn't the plant be able to photosynthesize? Like like ask on get. Third. Like it's going to need carbon dioxide Yeah because that is one of the reactants. So without sufficient reactants. The equation will not take place. And you've got to have sufficient amount of both of the reactants. You can have plenty of water, but if you haven't got enough carbon dioxide, it's not going to happen. And then if you get a buildup of the products, if you get a buildup of oxygen without it being able to leave the leaf, then you've got a problem. Right? Waxy cuticle was too thin, what would be the problem? And that can't get through. And the pthe plot gonna get too much sunlight. Meaning. Too much evaporation and too much water loss, and the plant would just start to shrivel up and wilt. Yep, so too much water loss. So water would start evaporating through the upper epidermis if you didn't have that waterproof, thick, waxy cuticle. And then you wouldn't have enough water. So it would just keep evaporating and it would just keep getting sucked up from the roots until it eventually all run out. Stmata could not open and close. What would be the problem there? Guys couldn't get in, and there's going to be the water couldn't get out. So like it can't photosynthesis anymore upset, so you wouldn't be able to get the oxygen and carbon dioxide entering and leaving the leaf, right? This is what we're going to do. Now just thinking I might actually give you this for your homework. So I'll just show you it. So you've had a similar thing before with your planning box. Remember, that won't be marked. That's just for you. Explain how a leaf is adapted for its role. And this is a very classic exam question. And here's your box for your answers. And let me tell you how many maps there are in total. Six Marks in total. So you've got absolutely plenty to talk about there. So that's your homework. So I'll pop that on for your homework. I think we've got a couple of questions on here. We'll just finish these off. Right, name the structure. Aspaces. There's something bundle, vascular bundle or xyom and flowem. You'll get the mark for either. One dream as the. Waxy key ticle. Yard sells good. How is, say, mssive film? And what are these structures that you can see that look a little bit like they're glowing? Spongy mesa bill no look at the shape of them. Matter. Thank you. So what part of the leaf are we looking at here? Bottom, the bottom of the leayeah. Yeah, they're a classic shape, so you should be able to recognize them. Okay, Linda. So I'll pop your homework in the chat. Maximum six Marks for that. And then I will see you next lesson, safe travels back home. Thank you, bye bye.