hi everybody and welcome back to miss Angler's biology class I am Miss angler in today's video we are going to do an introductory lesson to plant diversity because I know that this topic is going to be quite challenging and difficult and we need to lay down the basics before we get into the individual life cycles of each plant group now if you are new here don't forget to give this video a thumbs up and make sure you are subscribed with your notifications turned on because I post every Tuesday and Thursday and grade 11s I know that you need as much help as you possibly can and you should get your hands on my cheat sheet study guide for grade 11 it simplifies all of this work it makes it so easy to understand and it really does help you on your journey to getting that distinction in life sciences so let's dive into the content of the video today and I want to introduce you to the basic idea of evolution in plants so what we have in front of us here now is a very basic what we would call cladogram and you might have heard that word before it basically shows uh evolutionary change over time it's a little bit more linear and straight than maybe you would have seen in a philogenetic tree but we'll talk about that later and what I need you to understand is as we move left to right in this diagram we are moving from a very primitive plant that originated in a very primitive time on Earth so I want you to think of an earth that was mostly Rock and water no soil um very unregulated temperatures so extreme highs and extreme lows and as we move to the right we get a lot more what we would call Modern or newer plants and these plants had more resources available to them they had soil they had more regulated temperatures and so in order to survive they have evolved over time but we're going to start off with the most primitive plants and what we need to remember is we start talking about plant diversity and we look at how those plants reproduce that is the most important thing and when we look at the way they reproduce we need to look at water so again if we look from left to right we are actually looking at a Reliance on water for production where we have a really high Reliance on water to reproduce and then a very low Reliance and what do I mean by Reliance essentially um all of our nonvascular plants and I'm going to talk about that soon they require water to reproduce because their sperm cells are not delivered in pollen um they don't have any other mechanisms like flowers and so they have to put their sperm cells in water to deliver to the female reproductive organs but um on our vascular side they require little to no water so it's actually a scale we're going from a lot at the beginning and then less and then less as we progress now speaking of water another way that we classify plants is whether or not they have vascular tissue now vascular tissue if you have forgotten from grade 10 is when we talk about xylm and we talk about FL and remember those are the tissues that are going to transport food and water very very early on Plants remember our primitive plants down here they didn't have any vascular tissue as we progress over time we got more and more and more vascular tissue and it became more specialized now why is this important and often this is actually asked in exams why do we need vascular tissue well vascular tissue transports water right and food but the important part about transporting water is that you can live in drier areas you see our non-vascular plants like moss they must live in a wet area where there's lots of moisture but if you have vascular tissue you don't need to live in such a moist or damp area you can actually suck up water from the soil and therefore you can live live in a drier place again that's influencing plant Evolution the next thing we look at when we classify plants and we're looking at their diversity is do they have a cuticle again if we've forgotten what a cuticle is it is for water proofing and it is that waxy layer that's on the outside of leaves now again if you live in drier places as we mentioned earlier you probably also have a cuticle and so generally if you have a vascular tissue you will also have a cuticle now speaking of cuticle and having it on leaves the next thing we use to classify plants is their true organs now I say true organs because often there's a misconception about what it means to be a root a leaf a stem a flower you have to have true organs to be a true vascular land living plant and when you are a moss for example they do not have leaves or stems or roots and that confuses a lot of people because when you look at them you're like well aren't these like leaves and isn't this a stem and isn't there like you know some kind of root at the bottom remember a root a stem a leaf is an organ and in the structures of biology you need tissues doing all the same um jobs together to make an organ well in Moss they don't have organs they don't have a lot of different tissues doing a similar function they have one tissue doing one function that's why they can't be upgraded to having tissues that are then becoming organs like leaves and flowers now speaking of flowers and reproduction that is what we need to really unpack in this lesson so that you can progress onto the different life cycles successfully which brings me to alternation of generations now this is something that I really need everyone to wrap their heads around because we're going to use this in every single life cycle and if you struggle with this aspect it's going to be much more challenging later on alternation of generations literally means how a plant lives its life as a adult that's the generation the adult generation and then grows a reproductive organ so that it can make more of itself the baby generation now it's simple or it's easier to grasp when we look at flowers and seeds and pollen it's kind of we've already learned that in very basic level in in primary school but it is a little more complicated than that so now what we have to do is we have take our knowledge about cells and how reproduction works and we're going to apply to plants so the first thing we need to do is cut this alternation of generations in half and to make it nice and easy for us most plants are going to begin in this lower half here they are going to begin their life as a sporo or the spor ofy generation and so this is and I'm just going to use this very Loosely I don't want you to call it the adult generation but I just want you to think about it being the adult like the fully grown plant they are deployed which is this over here which means if if you're not so certain and you're unsure about that from learning mitosis um diploid means to have a full set of chromosomes so and I'm only using humans as an example humans would have 46 chromosomes if we were diploid and our hloy I'll put it above would be 23 I'm just going to use that as a reference for us just to help us even though we are not plant so we're going to start there at the sporo fide now the key word here is sporo that is going to tell us what that generation makes so this generation makes spores how does it do that it is going to go through the process of meiosis which is when you take your chromosomes and you half the chromosome number and you create spores now I want you to think of spores as a delivery mechanism right and so I'm going to keep it nice and simple because I'm going to use it rather as an example you're familiar with and let's say the Spore that you make is pollen because I think we're more comfortable with that idea pollen then goes through mitosis it gets bigger it gets more complex it gets packaged correctly and we have now entered the gametoy generation now as the name suggests a gametoy generation is going to create a Gam okay and what are gametes well let's not forget we have sperm and we have eggs that is what we are trying to make in this generation for now I'm just keeping it one so I'm just going to keep it male for now and so we take that pollen and it's going to go through a series of mitosis and eventually we are going to take that pollen grain over here and it's going to combine with another gamut which in this case would be an egg and that egg has been made in the in the female um part of this flower they join together in a process of fertilization which I know we understand what that is it's when an egg and a sperm cell fuse together and they produce a zygote now I know at this point it might be overwhelming but I'm going to go over this purely with a example and let's see if you can understand it with just the example and no fancy terminology so I want you to imagine that there's a plant that plant has flowers on it those flowers start to make pollen that pollen is going to ripen and mature and then a honeybee comes along brushes up against the pollen and delivers it to the egg which is also either on the same flower or on a different flower a neighboring flower that allows for fer ization to happen and the pollen now fertilizes the egg and this forms a future plant it could be a seed if it was a seeded plant if it has seeds this plant or if it's not and it's a more basic plant it will produce a zygote that will grow into a sporo once again now that is the simplest way I can explain it but every single plant group will have its very own life cycle based on this alternation of generations but with modifications because remember every single one has different bodily structures that either improve or assist its reproductive success now as always I like to end these lessons off with a terminology recap and I want to remind you that you can actually use the transcript from my videos to download it and you can upload it into something like chat GPT where you can actually make flashcard question questions straight off of my videos and they are scientifically correct for you to actually practice with and it saves you so much time now in terms of terminology let's go over so at the beginning we spoke about vascular tissue which remember is our xylam and Flo it is the structural tissue it allows plants to live on land and in dry places the cuticle was a protective waxy layer that is waterproof that plants use to prevent losing water and we often find cuticles and vascular tissues in the same plant if you don't have vascular tissue you generally don't have a cuticle we then moved on to alternation of generations and we looked at a sporify generation this is generally considered the diploid which is when you have a organism that has all the chromosomes in it and they produce spores spores are hlid or half and they are going to grow through um two processes one we're going to use meiosis to make the Spore and two we're going to use mitosis to uh mature the Spore once it's made in other words we're going to make it more specialized please also remember that meiosis halfs the chromosome number whereas mitosis maintains the chromosome number once you have made a Spore that has gone through mitosis it's going to grow and form a gametoy a gametoy is is a structure that is going to produce gamuts and gamuts are sperm cells and egg cells and they are needed for fertilization to continue the alternation of generations now if you like this video don't forget to give it a thumbs up and make sure you are subscribed with your notifications because I post every Tuesday and Thursday and I will see you all again soon bye