Question

BIOL 366 Mono and Dihybrid Crosses Recitation Problem Set Directions: For problems 1-6, do the following A. List how many genes are involved B. List how many alleles are involved. C. Identify symbols and genotypes / phenotypes D. List the genotypes of the parents E. Diagram and complete a Punnett square F. Give the phenotype percentages/ration of the offspring 1. In dogs, erect ears (E) is dominate over droopy ears (e). What are the results if two heterozygous dogs have a litter of puppies? 2、 The ability to roll the tongue (R) is determined by a dominant gene while the recessive gene results in the inability to roll the tongue (r). A man and his wife can both roll their tongues and are surprised to find that their son cannot. Explain this by showing the genotypes of all three persons. (Note: you do not need to do a Punnett Square for this problem). 3. In rabbits, the recessive hairless alilele (h) is embryonic lethal in the homorygous state in comparison to the dominant normal hair allele. Two heterozygotes cross. What are the phenotypic ratios of the rabbit pups born from this mating? The common grackle is a species of robin-sized blackbirds that are fairly common (hence the name) over most of the United States Suppose that long tails (L) were dominant to short tails in these birds. A female short-tailed grackle mates with a male long tailed grackle who had one parent with a long tail and one parent with a short tail. very deep and damp southeastern United States lives a giant flying cockroach known as a Paimetto bug. Assume that long antennae (L) are dominant to short antennae and that normal wings (N) are dominant to bent ones. What is the phenotypic ratio of a cross ween an individual that is homorygous dominant for antennae and heterozvgo us for wings individual that is heterorygous for antennae and homozygous recessive for wings? About 70% of Americans perceive a bitter taste from the chemical phenylthiocarbamide (PTC The ability to taste this chemical results from a dominant alilele (T) and not being able to taste PTC is the result of having two recessive alleles (t) Albinism is also a single locus trait with normal pigment being dominant (A) and the lack of pigment being recessive (a), A normally pigmented woman who cannot taste PTC has a father who is an albino taster. She homozygous, normaily pigmented man who is a taster but who has a mother that does not taste PTC 6. The following Punnett square§ show the results of four different crosses Gregor Mendel made with pea plants. in this case, Mendel was looking at flower color with Red (R) being dominarnt over white (r). Match the letter of the cross with the number of the appropriate squar (don't need to do steps D F here) 7

Questions 1-6

Answer 1

Enamau tei → on c Hatle-h the male nten enna Nosm nae