Question

1) Golana melons are renowned for their dark green flesh (G). However, some melons homozygous for flesh color are yellow. What would be the genotypic and phenotypic ratios if you crossed two plants with yellow-fleshed fruit? Be sure to answer both parts of the question and show your work!

2) In Vulpix, brown coat color (B) is dominant to white coat color (b). What would be the genotypic and phenotypic ratios if you crossed a heterozygous brown Vulpix with a white Vulpix. Be sure to answer both parts of the question and show your work!

Answer 1

1. The majority of Golana melons have dark green flesh (G). Some of them, however, are homozygous for yellow flesh color. Therefore, yellow is expressed only in the homozygous state. Hence, yellow (g) should be recessive to green (G).

A cross is made between two plants with yellow fruit. Hence, both the plants are homozygous recessive. Therefore, genotypically both the plants are gg.

Both the plants will produce a single-type of gamete i.e. g. Analyzing the cross using a Punnett square:

	g	g
g	gg	gg
g	gg	gg

Hence, as can be seen, the only genotype for all the offspring will be gg. This is the homozygous recessive state. Therefore, the phenotype will also be recessive. Hence, phenotypically, all the offsprings will have yellow-fleshed fruit.

2. The trait under examination is the coat color of Vulpix. It is controlled by a single gene which has two alleles at the locus. These are B and b. B codes for brown coat color and is dominant over b which codes for white coat color.

A cross is made between a heterozygous brown and a white Vulpix. The genotype of the heterozygous brown Vulpix will be Bb. The genotype of the white Vulpix will be bb.

Analyzing the offsprings from a Punnett square:

	B	b
b	Bb	bb
b	Bb	bb

There are two possible genotypes of the offsprings and these are Bb and bb. Bb is heterozygous state and the phenotype expressed will be the dominant one. Hence, the phenotype of Bb offsprings will be brown coat color. Similarly, bb is homozygous recessive state and hence the phenotype expressed will be recessive one. Hence, the phenotype of bb offsprings will be white coat color.

Therefore, there are two genotypes Bb and bb with equal proportions. And also there are two phenotypes brown coat color and white coat color with equal proportions.