Incomplete dominance










1. In northeast Kansas there is a creature know as a wildcat. It comes in three colors, blue, red, and purple. This trait is controlled by a single locus gene with incomplete dominance. A homozygous (BB) individual is blue, a homozygous (bb) individual is red, and a heterozygous (Bb) individual is purple. What would be the genotypes and phenotypes of the offspring if a blue wildcat were crossed with a red one?
 

Genotype:
 

 
 

Phenotype:
 








What are the genotypic and phenotypic ratios of the F2generation?

Genotypic ratio (BB:Bb:bb):
 

 
 

Phenotypic ratio (Blue:Purple:Red):
 


2. The lubber grasshopper is a very large grasshopper, and is black with red and yellow stripes. Assume that red stripes are expressed from the homozygous RR genotype, yellow stripes from the homozygous rr genotype, and both from the heterozygous genotype. What will be the phenotypic ratio of the F1 generation resulting from a cross of two grasshoppers, both with red and yellow stripes (red : both : yellow)?
 

 
 

What would be the genotypic ratio of the F1 generation (RR : Rr : rr)?
 

 
 

What genotypes would be produced by crossing a grasshopper with both color stripes and one with yellow stripes (choose all that apply)?
 

 
 

What phenotypes would be produced by crossing a grasshopper with both color stripes and one with yellow stripes (choose all that apply)?
 

 


3. Suppose you have two rose plants, both with pink flowers. You cross the two plants and are surprised to find that, while most of the offspring are pink, some are red and some are white. You decide that you like the red flowers and would like to make more. What cross would you perform to produce the most red flowered plants?
 

 
 

Your mother decides she would like some of the pink flowered roses. Which cross would give you the most pink flowered plants?
 

 


4. A naturalist visiting an island in the middle of a large lake observes a species of small bird with three distinct types of beaks. Those with short, crushing beaks (BB) consume hard shelled nuts, those with long, delicate beaks (bb) pick the seeds from pine cones, and those with intermediate beaks (Bb), consume both types of seeds though they are not as good at either. Assume that this difference in beak morphology is the result of incomplete dominance in a single locus gene. Which of the mated pairs below will have the best adapted offspring in a year in which most of the food available is in the form of hard shelled nuts?
 







What would be the phenotypic ratio of the F1 generation resulting from a cross of Bb x bb (Short:Intermediate:Long)?
 

 
 

How many offspring of an intermediate x short beak cross will have long beaks (assume 4)?
 

 


5. Racoons have rings around their tails and a habit of washing their food in water before eating it. Suppose that both of these traits are controlled via incomplete dominance so that wide bands on the tail are BB, medium sized bands are Bb, and narrow bands are bb and that washing all their food is WW, washing some of their food is Ww, and washing no food is ww. How many of each genotype will be in the F1 generation resulting from a cross of two racoons, both with medium sized tail bands and that wash some of their food (assume 16)?
 
BBWW:
BBWw:
BBww:
BbWW:
BbWw:
Bbww:
bbWW:
bbWw:
bbww:







How many of the F1 generation will have wide tail bands and won't wash any of their food?
 







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