DRAW IT Two pea plants heterozygous for the characters of pod color and pod shape are crossed. Draw a Punnett square to determine the phenotypic ratios of the offspring.

Video transcript

Hi everyone. Let's look at our next problem. Two p plants. Hetero ziggy's for the characteristics of size and flower color are crossed and the punnett square for this cross is given below what will be the fanatic ratios. So we want to look at of the descendants of this. Heterocyclic cross. What's the ratio of each phenotype we see from our answer choices that we've got four different phenotype. It's possible. So let's just remind ourselves of the genotype possibilities to refer back to our square. So for size we've got two possibilities tall and dwarf. And for color we've got violet and white. Well we've got a big T. And little T. So tall is the dominant trait. So there's two genotype that will give us tall. Either a big T. Big T. Or big T. Little T. Since tall is dominant and only one genotype possibility for dwarf little T. Little T flower color. We've got big B. And little V. So violet here, the dominant trait. So we just need one big V. We just need one big V. To give us the violet trait. But we need to little V. S to give us the white trait. So with that in mind let's look far square and see what ratio of types we get in the offspring. So our first phenotype we're going to look at is tall and violet. So the showing both dominant traits that's going to be our most common phenotype since they only need to have one of the dominant gene. So I'm going to highlight in blue and we can do that rather quickly by looking for instance at this first column. If they inherit a big T. And a big B. From the male parent here. This entire column will be both tall and violet. Since they only need to inherit one dominant gene from the parent. Same with the first row. If they inherit big T. Big T. From the female Karen this whole row will be tall and violet. So very quickly we see that. So let's look through the rest of our remaining squares and find anything that would show the traits of tall and violet. So at least one dominant gene Of each type. And we see there are two more. So that gives us a total of nine tall violet offspring in this square. So let's look through our answer choices and identify the ones that show nine tall violet offspring. And that would be choice C. And choice D. A. And B. Don't have the correct number there. So they cannot be our correct answers. We'll just cross them off. Now I'm going to switch strategies. I first looked for the most common expected offspring and now I'm going to look at the offspring showing both recessive traits. So they have to have little T. Little T. Little V. Little V. That's the only possibility and there's just one square in which they inherit all the recessive genes from both parents. So we expect to see only one offspring In the ratio there. So I'm going to look for the answer choice that gives us that and only choice c. shows us one dwarf white. So now we know we can eliminate choice D. And Choice C. Must be our correct answer here. So I'm going to go ahead and circle that as our correct answer. And to be thorough we can just check and make sure shows tall white. We expect to see three squares. So yes indeed. We see. Oops switch that highlighted there. I'm gonna highlight that in red, expect to see tall white. They're tall white there and tall white there so three tall white offspring and left and white here. Three that will be dwarfed violet. So choice see here shows are correct answer of the expected fanatic ratios in the offspring. See you in the next video.