A black and white rabbit were mated. All F 1 offspring were black, and the F 2 offspring is made up of approximately ¾ black and ¼ white rabbits. • Draw out two Punnet squares detailing both matings. • Supposed two white F 2 offspring were mated. What would be the phenotype and genotype of the F 3 offspring?

Okay. So in this question, we're going to get a lot of practice doing monohybrid crosses and Punnett squares. So this says that a black and a white rabbit were mated, and all f one offspring were black, and all the f two offspring were makeup of 3 fourths black and one fourth white rabbits. And it says draw out 2 punnet squares detailing both matings. Now, the thing that I didn't give you were the genotypes of the parents or the f one offspring. All I did were give you the phenotypes. And so in this question, we're going to draw 2 phonetic squares, but we're going to draw them backwards. We're going to start with the offspring from the f two generation, figure out what the genotype of the f1 is, and then use that to also figure out what the genotype of the parents are. And so it's going to be a little bit it's going to be reverse of what you're used to, but I think that's good because if you can do Punnett squares from the top down, so if you have the genotypes produce the offspring. But if you also can do them from the bottom up where you're given the offspring and you can find the genotypes of the parents, then you're gonna be doing Punnett squares all the time left to right and have it down completely. So let's start with the first one. So remember, we're gonna start with the f two offspring. And so this is our punnet square here. And let me disappear so I have more room. So what we don't know is this. Right? We have no idea what this is, but we do know that 3 fourths of the rabbits were black and one of them is white. So in order to be white, we're just gonna do that lower case b. Right? Because it's most likely recessive. We haven't gotten into any of the weird things that we're going to talk about yet. So far, we've only talked really about dominant and recessive and so for it only to be 1 out of the 4 rabbits be white, that's most likely recessive. So in order to be white, it has to get one allele, right, from both parents. So automatically, we already know that this allele came from this parent and this allele came from that parent. And so with that knowledge, we can figure out this allele because we know that all the f1 offspring, which are the parents, right? So the f2 offspring that's produced from f1 parents. So the parents were all black and so if they are black, that means that they are going to have a dominant allele, the dominant b allele. So we can produce this offspring, string, right? And what we get is we get 3 fourths black, right? 1, 2, 3, and 1 fourths white, which is exactly what the question says. So now we know that our f one generation was this. So using that information, we can figure out what the parent genotypes are. So this is our 2nd Punnett square. So remember, we don't know what the parent genotypes are, but we do know that all the children were black and they have this genotype. Right? Because we calculated that here. So in order to do this, there has to be one parent that was black, so the black parent is going to produce the b allele, so we at least know that has to be true. And we know that the other parent was white. So in order to be white, it has to be, homozygous recessive for that lowercase b allele. So in order for these to also get this dominant, the parents have to be homozygous dominant times homozygous recessive. And we know this because we were given the colors and we had the offspring. So these are the 2 Punnett squares you should draw out for question 1. Now part b or part a. So part b says, suppose 2 white f two offspring. So that would be oops. Sorry about that. So that would be if we are looking at this. This is the white 2 offspring. And it says, suppose 2 of them were mated, what would be the phenotype and genotype of the f 3 offspring? So in order to do this, we just need to draw another Punnett square. Right? So for doing this mating, it's going to turn out that all 4 of the offspring will be homozygous recessive and that means that they'll be white. And so I use b here but this is showing as a. It doesn't matter what letter you use, but in this case these are homozygous recessive and it's white. So the answer here for the f3 offspring, which we calculated in this Punnett square, is going to be white and homozygous recessive. So, with that, hopefully you got some good Punnett square practice. And so, let's move on.

A black and white rabbit were mated. All F1 offspring were black,...

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