A pea plant that has the genotype RrGgwwdd is crossed to a pla...

Question

A pea plant that has the genotype RrGgwwdd is crossed to a plant that has the rrGgWwDd genotype. The R gene controls round versus wrinkled seed, the G gene controls yellow versus green seed, the W gene controls purple versus white flower, and the D gene controls tall versus short plants. Determine the following;

What are the phenotypes of each plant?

What are the phenotypes of each plant?

Accepted Answer

Everyone. Let's take a look at this question together. If we cross an organism with big, a little A big B, big B, big C, big C and big A big A big B little B little C little C genotypes. What is the probability of producing a big A big A big B little B big C little C genotype. Is it answer choice? A 1/4 answer. Choice, B 3/4 answer choice C 5/ or answer choice D 1/8. Let's work this problem out together to try to figure out which of the following answer choices is the correct answer. So to calculate the probability of producing that final genotype, we can go ahead and set up three individual punt squares for each trait in order to determine what the probability will be for each individual trait and then multiply them together at the end to figure out the probability of producing that big A big A big B little B big C little C genotype. So in our first punt square, we can go ahead and do the cross for trait A in which we cross that heterozygous with the homozygous dominant. So in the top of our first pundit square, we can go ahead and put the heterozygous and on the left, we can put the homozygous dominant, which we know when we do the cross between these two, we end up with 50% of our offspring being homozygous dominant and 50% being heterozygous. And we wanna know what the probability of producing that homozygous dominant is for trait A which we know is 50% or one half, which we can put on the bottom. And then multiply that by the probability for the other two traits at the end, which next we can go ahead and calculate the probability of trait B which we have in the top, our homozygous dominant. And on the left, we have our heterozygous, which we know when we fill out this square for trait B, we have 50% being that homozygous dominant and 50% are heterozygous, which we want to find out the probability of trait B being that heterozygous genotype, which is one half. So we can put that on the bottom to multiply by trait A and trait C's probability to figure out our final probability, which lastly, we will do our third and final pundit square for trait C which we are crossing that Homozygous dominant with the homozygous recessive, which will give us 100% of the offspring as heterozygous. And we wanna know what the probability of producing that heterozygous genotype is for trait C which we know is four out of four, since four out of four of the offspring are heterozygous, which we can put is one. And so to figure out the final probability of producing that big A big A big B, little B, big C little C genotype is as follows, one half, multiplied by one half, multiplied by one which we get as the probabilities for each individual trait from doing our three punnet squares. And when we multiply those three together, we end up with 1/4 as the probability of producing that genotype, which means that answer choice. A 1/4 is the correct, correct answer. Because when we cross the two organisms genotypes together, the probability of producing that big A big A big B little B, big C little C genotype is 1/4 which is answer choice. A the correct answer. I hope you found this video to be helpful. Thank you and goodbye.

Key Concepts

Genotype vs. Phenotype

Dominant and Recessive Alleles

Punnett Square

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