 you cannot talk about a group of critters without talking about how they make babies. And so we have to talk about the plant life cycle because it's crazy. All right, before we can talk about the plant life cycle, of course we have to talk about our own because you know what, nothing makes sense unless we can connect it to our own like coolness. So I'm going to draw you a picture of what do you suppose the human life cycle. And instead of doing it in my normal way, I'm going to divide the human life cycle into a haploid stage. So anything, any cell or critter or whatever that is haploid is going to go above my line. And then I'm going to have a diploid stage. So any part of the life cycle that is diploid is going to go below the line. Now, push pause. You guys are brilliant. You can totally do this. So see if you, if you push pause, go ahead and start with a critter, which would be like you, a diploid to an adult. And you can make it all cute if you would like. But start there and go ahead and what does the life cycle actually look like if you were to start with the diploid critter, us, and go into haploid then. Go ahead and push pause and attempt to do that. Well, what I want you to get, if you did that, like a good person, I want you to remember that we go through the process of meiosis, right? And what do we get at the end of meiosis? We get sperm and eggs. And sperm and eggs are, of course, most joining by all love. Sperm and eggs are haploid cells. And the haploid cells combine through the process of fertilization, right? But then what do they become? They become a diploid critter. They become a diploid zygote, which grows into a diploid adult. So you can see here that we have this process where a diploid critter makes a single-celled haploid gamete that combines with somebody else's single-celled haploid gamete that then join to form a zygote, which goes through mitosis to make an adult. Totally straightforward. Absolutely what you would expect. Let's compare that to what happens with a plant. Well, plants have a diploid adult, okay? And different kinds of plants are going to take on this task a little bit differently. So instead of just saying, you know, of course, any plant you see is going to be a diploid adult, we're going to call, we're going to name this thing. The diploid adult is called a sporophyte. Sporophyte. And each group of plants that we're going to talk about, there's four of them. I'm going to show you who the sporophyte is. I'm telling you that the sporophyte is diploid. Now, sporophytes also go through the process of mitosis. And it makes sense that the result of mitosis is a haploid gamete. So look, you get a haploid gamete. So let's just go ahead and say, you know, we'll call it a sperm. Here could be an egg. Here's the coolness factor. I called it a gamete. It's actually, I'm going to erase that because it's actually a spore. Sporophytes make spores through the process of mitosis. It's going to make more sense to you in just a second. Now, remember, this is haploid. Are you ready? This is crazy talk. Haploid spore, which is like a little sperm, it's a product of mitosis, is going to grow into a multicellular haploid adult. What? True story. This diploid adult was called a sporophyte. This haploid adult is called a gametophyte. Dude, I mean, that's phenomenal. And then, this haploid, it's a grown-up. I'm going to show you pictures of gametophytes. It's like a sperm that becomes multicellular and walks around, except plants don't walk around. But if it was like an animal sperm, it'd be a walking sperm, it'd be a sperm walking down the street. It's a grown-up, but it's a haploid. If its sperm went through mitosis and made multicellular sperm and walked around, we'd have this kind of life cycle. We don't. Guess what the gametophyte does? The gametophyte makes gametes. Now, what do you think is true about the gametes? Did we go through meiosis to make those gametes? No, we don't even have homologous chromosomes to hook up during prophase one. This is just through the process of mitosis that you get, that says mitosis. You get gametes. And then, we've got haploid gametes from different critters that combine what? To make a haploid, I mean a diploid zygote. Dude, seriously? A diploid zygote grows into a sporophyte through the process of mitosis. Seriously? I mean, that's phenomenal. It's called an alternation of generations life cycle. And it makes sense because in one generation, you have a haploid grown-up, and in the next generation, you have a diploid grown-up, and then in the next generation, you have a haploid grown-up, and so you get this alternation of generations. All plants do it. They have different takes on it. And the first group of plants that we're going to talk about are the mosses. We're going to start out by breaking down our cladogram a little bit just for the land plants so that we can kind of keep ourselves oriented to this whole process. But don't forget that we're going to look at all of them and how they do this alternation of generations. I'll be right back to talk about moss madness.