The crosses shown are performed between morning glories whose flower color is determined as described in Problem 24. Use the segregation data to determine the genotype of each parental plant.

Question

Table showing parental and offspring phenotypes for morning glory crosses in genetics.

Accepted Answer

Hey, everyone. Let's take a look at this question together. The shape of summer squash is classified as either long, spherical or disk shaped, disk shaped fruits are produced when dominant alleles are present at two gene loci A and B spherical shaped fruits are produced when a dominant allele is present at either the A or B gene loci and long shaped fruits are produced when the plant is homozygous recessive or both genes A and B. When a plant that produces spherical shaped fruits is crossed with a plant that produces long shaped fruits. The phenotypic proportion of the progeny obtained is as follows, one half spherical fruit and one half long fruit based on the segregation data determine the genotype of the parents. So from the question, we know what the genotypes are or the plants that produce fruits that are either long, spherical or disk shaped. And we know that our offspring are one half spherical and one half long, which we know that the spherical shaped fruits are produced by plants with the genotype containing a dominant allele present at either the A or B gene loci, which means we will have a dominant allele in A or a dominant allele in B. And we note that our long shaped fruits are produced by plants with a genotype having the homozygous recessive for both genes A and B. So we have that homozygous recessive for A and B. So we need to determine what the genotypes are for the parents that produce one half serle and one half long shaped fruits. And so we know that the parents must b heterozygous or A or B as well as crossed with the homozygous recessive or A and B in order to ensure that we get those long offspring. And so looking at our answer choices, which answer choices do we see contain a parent that is heterozygous for A or B and another parent that is homozygous recessive or A and B which we know in answer choice A, we have that heterozygous for A and we have the homozygous recessive. And so answer choice A is a possible cross for the genotypes of the parents. And looking at answer choice B, we can see that we have that heterozygous four B being crossed with that homozygous recessive for both, which means that answer choices A and B are both possible genotypes of the parents. And so answer choice D is the correct answer because we know that the genotypes found in answer choice A and in answer choice B will result in that one half of the offspring being spherical and one half being long shaped. And we note that it is not answer choice C because that will not give us the phenotypic proportion of the progeny that we have obtained. And instead give us progeny that produce spherical fruits only. So answer choice C is incorrect and answer choice D is the correct answer. I hope you found this video to be helpful. Thank you and goodbye.

The crosses shown are performed between morning glories whose flower color is determined as described in Problem 24. Use the segregation data to determine the genotype of each parental plant.

Verified video answer for a similar problem:

Key Concepts

Mendelian Genetics

Phenotype and Genotype

Punnett Square