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In tomato plants, the allele for purple stems is dominant to allele for green stems and the allele for red fruit is dominant to the allele for yellow fruit. Create a Punnett Square and state the genotypic and phenotypic ratios for the offspring if two tomato plants heterozygous for both traits are crossed.

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midknight9

So let's call the allele that is dominant for purple stems is P, and the recessive allele yielding green stems is p. And let's say that the allele that is dominant for red fruit is R and the recessive allele for yellow fruit is r.


The two plants are each heterozygour for both traits, meaning that the cross is going to be:


PpRr x PpRr


So let's setup a Punnet Square:


[tex] \left[\begin{array}{ccccc}&PR&Pr&pR&pr&PR&PPRR&PPRr&PpRR\4&PpRr&Pr&PPRr&PPrr&PpRr&Pprr\\pR&PpRR&PpRr&ppRR&ppRr&pr&PpRr&Pprr&ppRr&pprr\end{array}\right] [/tex]


The genotypic ratios (alleles) and phenotypic ratios are as follows:


PPRR (Purple stem, Red fruit): [tex] \frac{1}{16} [/tex]


PpRR (Purple stem, Red fruit): [tex] \frac{2}{16} [/tex] or [tex] \frac{1}{8} [/tex]


ppRR (Green Stem, Red fruit): [tex] \frac{1}{16} [/tex]


PPRr (Purple stem, Red fruit): [tex] \frac{2}{16} [/tex] or [tex] \frac{1}{8} [/tex]


PPrr (Purple stem, Yellow fruit): [tex] \frac{1}{16} [/tex]


PpRr (Purple stem, Red fruit): [tex] \frac{4}{16} [/tex] or [tex] \frac{1}{4} [/tex]


pprr (Green stem, Yellow fruit): [tex] \frac{1}{16} [/tex]


ppRr (Green stem, Red fruit): [tex] \frac{2}{16} [/tex] or [tex] \frac{1}{8} [/tex]


Pprr (Purple stem, Yellow fruit): [tex] \frac{2}{16} [/tex] or [tex] \frac{1}{8} [/tex]


So then we take the like phenotypic ratios and add them together:


Purple stem, Red fruit: [tex] \frac{1}{16} +\frac{2}{16} +\frac{2}{16} +\frac{4}{16}=\frac{9}{16} [/tex]


Green stem, Red fruit: [tex] \frac{1}{16}+ \frac{2}{16} =\frac{3}{16} [/tex]


Purple stem, Yellow fruit: [tex] \frac{1}{16}+ \frac{2}{16} =\frac{3}{16} [/tex]


Green stem, Yellow fruit: [tex] \frac{1}{16} [/tex]

Oseni

The genotypic and phenotypic ratios would be as found below:

Let the stem color be represented by allele A and the fruit color by allele B.

Since purple color in the stem is dominant (A) while green color is recessive (a), a heterozygous individual will be Aa.

For the fruit color, a heterozygous individual will be Bb.

An individual heterozygous for both traits will have the genotype AaBb

Crossing AaBb and AaBb: see the attached image for the Punnet's square result.

Genotypic ratio:

AABB - 1/16

AABb - 1/8

AaBB - 1/8

AAbb - 1/16

aaBB - 1/16

AaBb - 1/4

Aabb - 1/8

aaBb - 1/8

aabb - 1/16

Phenotypic ratio:

A_B_ - 9/16 = purple stem, red fruit

aaB_ - 3/16 = green stem, red fruit

A_bb - 3/16 = purple stem, yellow fruit

aabb - 1/16 = green stem, yellow fruit

More on dihybrid crosses can be found here: https://brainly.com/question/1185199?referrer=searchResults

Ver imagen Oseni

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