The duck-billed Parasaurolophus has a huge crest through which its nasal passage

Question

The duck-billed Parasaurolophus has a huge crest through which its nasal passages run. calit ,fparatus ls used to roduce loud calls. You find that the animals produce two kinds of and whistles. A single gene controls sound and hooting (H) is dominant to whistling (h) . You also find that the crests come in bright colors. Color is controlled by a single gene and blue (B) is dominant to red (b). The two qenes are on different chromosomes and so they assort independently. Let s say you have a pure-breeding Blue Hooter and a pure-breeding Red Whistler. Give the genotypes of these animals. Show the types of gametes they would produce. If you were to cross these animals, give the genotype and phenotype found in the F1. Show the types of gametes that the F1 animals could produce. If you were to cross two members of the F1 with each other, what phenotypes could occur in the F2? What would be the proportions of the different phenotypes in the F2? Ok - we'll move out of Jurassic Park now for some more practice. . . In smileys, the shape of the eye is controlled by multiple alleles. The smileys pictured show the four possible phenotypes. It is known that the star and dot eyes are codominant and the square eyes are a recessive trait.

Explanation / Answer

7. a] It is possible to have 3 phenotypes from 2 alleles if its a case of co-dominance. In this the homozygous states of genotype will show red and white color and heterozygous will give roan color.

b] Let the genotypes be-

RR - red / WW - white/ RW - roan. The rancher has roan and white colored animals. So cross between RW and WW would give - RW and WW again. So there is no chance he can have red animals, unless there is any red parental animal. This is because the alleles show co-dominance.

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