 Say my mom has blue eyes and my dad has brown eyes. What color would my eyes be? Now for a long time people thought that the color of my eyes would just be a mix of the color of my parents. So it would be a mix of blue and brown. So some kind of a dark brownish blueish eyes. And that's what they believed for every single trait. So for example, my mom has straight hair. Dad has let's say curly hair. Then again they believed I would get a mix of them. Kind of straight, kind of curly, wavy hair. And so for a long time people thought this is how traits get passed or inherited from parents to children. It will just be a mix. The traits will just be a mix in the children. But is this really how traits get passed on? Who's going to answer this question? Well, there was one man actually a monk named Gregor Mendel who decided he's going to answer this by growing a lot of pea plants in his garden. Now if you're wondering why he chose pea plants then we've talked a lot about this in a previous video talking about how pea plants have a lot of characters to experiment with and how these characters have only a couple of traits and all of that. So if you need a refresher it'll be a great idea to go back and watch that video on which is called Why Mendel Chose Pea Plants. But if you feel you're cool with this then let's go ahead and see what kind of experiments Mendel performed on these pea plants. So Mendel performed a lot of experiments on different characters. So let me take one example, the character height. So what he would do in one of his experiments is he would take a pure tall pea plant and then cross-fertilize it with a pure short pea plant and then see what offspring they would give. Now I'm pretty sure you might be wondering what do you mean by pure plants? What does this pure mean? Pure basically means if you were to self-pollinate them so if you were to self-pollinate a tall plant it should give all tall plants. If you self-pollinate a short plant it should give all short plants. And what do you mean by self-pollination? Well, suppose this is one of the flowers of the tall plant then what I mean by self-pollination is you take the, you take the, what do you call this, pollen grains, yeah. You take the pollen grains from the flower and put it back into the carpal of the same flower. Basically you put it back into the female reproductive part of that same flower and then it'll grow seeds and then you sow those seeds and then if you find that all the seeds grow into tall plants then that, then we will say this is a pure tall plant. This is the meaning of pure and similarly if you were to do the same thing for the short plant as well so you take one of the flowers of that short plant and then you self-pollinate meaning you take the pollen grains put it back into the same flower, let it fertilize and then you grow seeds and you sow them and if you find all of them grow into short plants not a single tall plant but all of them grow into short plants then we will call this a pure short plant. So Mendel prepared these pure breeds for his experiment a pure tall plant and a pure short plant. Let me get rid of these now. And so for his experiment you know what he does he cross-pollinates them meaning he takes the pollen grains from one of the plants and he puts it into the flower of the other and you can take it from anyone to anyone. So for example he might take the pollen grains of flower from the tall plant and then put it into the carpel or this part of the short plant so let's say he cross-fertilizes them like this and then this will start growing seeds then he sows that seeds to see what we will get after this cross-fertilization. So what do you think we will get? Well let's get rid of the flowers and make some space. So what do you think we end up with? Well I would expect to get some medium height plants because you have a short one, you have a tall one, you have a short one so maybe they get mixed and you end up with all medium-sized plants. That's a reason able to think right? But to mental surprise and to even my surprise when I learned this we get all tall plants. What? That's right, big shock, 100% of them, 100% of them end up being tall. This raises many questions. What happens to the short one? Does it have no effect at all? Why aren't we getting any medium-sized plants? Why aren't we getting any short plants? What is going on? Anyways, he addressed these plants as F1 generation plants. That's just the name that he used them. And if you are wondering why he called them F1, the word F stands for a Latin word filial. I hope I'm pronouncing that right. It means son or daughter. So that's why these plants are called F1 generation. F1 generation sons or daughters of these, you can say. But yeah, Mendel was shocked by this. So he didn't stop over here. He started asking questions. One of the main questions he was asking is, are these plants, these tall plants, the same as the parent tall plant? Are they the same? They look the same because they have the same height, but are they really the same? Is this also a pure tall plant? That's the question he started asking. And to answer that question, you know what he did? He did another experiment. He didn't stop over here. What he does next, what he does next, is he takes one of the F1 generation plant, which is basically tall. He takes one of the F1 generation plant. This is F1 generation. Oops, let me use this white color. So this is F1 generation. And he self pollinates it. Self pollinates it to see what we get. So again, it will grow seeds. And then he sows that seeds. What do you think we'll end up with? Well, surprise, surprise. Now, some short plants are found. Another shocking thing to see, right? Because again, where did these short plants come now from? Suddenly, right? And guess what? Mental even counted them. So in this F2 generation, this is the second generation sons and daughters, or offsprings. When he counted them, you know what he got? He found that there were roughly three times as much tall as you had compared to short. So the tall to short ratio was three is to one. And if you're wondering, yes, he also cross pollinated the F1 generation plants and he gets exactly the same result. Three is to one. And you know why this number is so important? Because it's not random. It turns out he gets the same answer for all the characteristics that he experiments with. I mean, for example, when he takes the color of the flower into consideration. Again, he takes a pure purple colored pea plant and crosses it with a pure white pea plant. In the first generation, you know what he gets? A similar result. This time he gets all purple colored flowers. No yellow or no white flowers at all. But then when he takes one of these F1 generation purple flower and self pollinates, guess what he gets? He now gets three times as much purple as white. White comes back. It's in minority, some small amount, three is to one ratio. But it comes back with the same ratio, three is to one. So what's going on? Why didn't we see the white flower over here? But somehow it comes back in the next generation. What is going on? Before we think of what's really going on, one thing is very sure. Our initial assumption that traits get mixed and sent to their children is absolutely wrong. Isn't it? I mean, if that was the case, we would have found some medium plants over here. Or over here, we would have found some pinkish colored flower, mix of purple and white. But we don't get that. So Mendel from his experiments conclusively proved that traits do not get mixed at all. That in itself was a huge discovery. But now he had to figure out what it all meant. And I'm going to leave you here hanging with this question as Mendel must have been left hanging with. We will look at the exciting conclusion of what all this means in the future videos. Meanwhile, ponder on this for a while. See if you can come up with any theory to explain this.