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. This apparatus is used to produce loud calls. You find that the animals produce two kinds of calls, hoots 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 gene 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 (FOIL). 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 (FOIL), 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?

Explanation / Answer

(a) The genotype of Pure breeding Blue Hooter is HHBB; and pure-breeding Red Whistler is hhbb.

(b) Gametes produced by Pure breeding Blue Hooter (HHBB) are all HB; gametes produced by pure-breeding Red Whistler (hhbb) are all hb.

(c) Pure breeding Blue Hooter (HHBB) and pure-breeding Red Whistler (hhbb) will have the following parental and offspring genotypes .

HHBB* hhbb --------> 100% HhBb---> F1 (Blue hooters)

(d) Gamets produced by F1 offspring are, HB, Hb, hB and hb.

(e) Cross between F1 offspring will have the offpsring with the following genotype and phenotypes.

HhBb* HhBb = HHBB (1/16, blue hooter), HHBb (1/8, blue hooter), HHbb (1/16, red hooter), HhBB (1/8, blue hooter), HhBb (1/4, blue hooter), Hhbb (1/8, red hooter), hhBB (1/16, blue whistler), hhbB (1/8, blue whistler) hhbb (1/16, red whistler).

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