Two pure-breeding wheat strains, one producing dark red kernels a...

Question

Two pure-breeding wheat strains, one producing dark red kernels and the other producing white kernels, are crossed to produce F₁ with pink kernel color. When an F₁ plant is self-fertilized and its seed collected and planted, the resulting F₂ consist of 160 plants with kernel colors as shown in the following table.

Kernel Color Number
White   9
Dark red 12
Red 39
Light pink 41
Pink 59

Based on the F₂ progeny, how many genes are involved in kernel color determination?

Accepted Answer

Hello, everyone and welcome to today's video. So, a cross is made between two pure breeding wheat strains, one with dark red kernels and the other with white kernels. The F one plants produce pink kernels and when the F one plants were so fertilized, the F two generation had nine white, 12 dark red, 39 red, 41 light pink and 59 pink kernels. What is the likely number of genes involved in the determination of kernel colors in this population? So as answer choice A we have one gene B, two genes C, no genes D, the actual number of genes can be predicted based on this information. Now, in order to solve this problem, let's understand that the parents or the original two organisms that we were crossing are pure breeding for dark red and white kernels. Let's assign the G eight to these two. So pure breeding for, let's say dominant being dark red and pure breeding for recessive being white. Once they crossed, they form these pain kernels which are going to be these heterozygous kernels and they are pink. So they're a different color than their parents. So this is a type of incomplete dominance. Now, once we solve fertilize these, now the the genotype or the phenotype ratio that we're going to be observing should be 1 to 2 to one. So we should have three different phenotypes. However, we have five, we have white, dark red, red, like pink and pink kernels. So these would be, these three pheno types will be the result of us using only one gene to obtain the color trait of these kernels. However, this information suggests that that it is not just one gene but two genes controlling the color trait of these kernels. And this is because there were five phenotypes in the F two generation rather than the normal three that we were supposed to obtain. And because of this, the correct answer for this question is going to be B two genes. I really hope this helped and I hope to see you on the next video.

Key Concepts

Mendelian Inheritance

Phenotypic Ratios

Polygenic Inheritance

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