Ch.9 Genetics
Problem Set II: Non-Mendelian Genetics
Obj. 9.11-15
INCOMPLETE DOMINANCE:
In fouro’clock flowers, the gene for red flowers (R) is incompletely dominant to the gene for white flowers (r).
The heterozygous condition results in pink flowers. A gardener crosses two red fouro’clocks. name: block: score: / 25 pts.
In
Andalusion fowl (a type of chicken), B is the gene for black feathers. W is the gene for white feathers. The genes show incomplete dominance. The heterozygous condition results in blue feathers.
1.
What are the expected genotypic and phenotypic results and ratios?
1 pt. G:
1 pt. P:
Incomplete dominance is involved in the breeding of
Dalmatian dogs. The spotted Dalmatian is the result of crossing a pure black dog with a pure white dog.
2.
What type of pups could you expect if you crossed a
Dalmatian (BW) with a pure black dog (BB)? Include in you answer the genotypes, phenotypes and the expected ratios of all possible offspring.
1 pt. G:
1 pt. P:
Yellow coat color in guinea pigs is produced by the homozygous genotype (YY), cream color by the heterozygous genotype (YW), and white by the homozygous genotype (WW).
4.
List the genotypic and phenotypic ratios expected from the crosses:
1pt. black x black:
G:
P:
1pt. black x blue:
G:
P:
1pt. blue x blue:
G:
P:
1pt. blue x white:
G:
P:
3.
What genotypic and phenotypic ratios are produced by a mating between two cream colored guinea pigs?
1 pt. G:
1pt. P:
Mrs. Loyd
 cloyd@waukee.k12.ia.us
Radishes may be long, round, or oval. Crosses of long and oval gave 159 long and 156 oval. Crosses of oval and round produced 203 oval and 199 round. Crosses of long and round gave 576 oval.
1
1 pt.
Explain how this could be.
CODOMINANCE:
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Red and white coat colors in some animals are codominant to one another. This means that neither allele turns the other one “off,” and both are fully expressed.” If a horse with red coat color (RR) is crossed with a horse with white coat color (WW), the offspring will have a coat color called, “roan” (RW).
1.
Give the genotypic and phenotypic ratios of a cross between a white horse and a roan horse.
1 pt. G:
1 pt. P:
CODOMINANCE & MULTIPLE ALLELES:
Human blood types also show codominance for the proteins that are on the surface of the red blood cells.
The proteins are: A, B, or O. (Think of the O as zero protein.) Blood types also show multiple alleles . (Each person has two alleles but there are three alleles present in the population.) AA and AO are phenotypically type A.
BB and BO are phenotypically type B. OO (no protein) is phenotypically type O. A and B proteins are codominant and both protein types appear on the surface of each red blood cell.
2.
If a mom with type A blood and a dad with type B blood had a child, could the child be type O? Draw a
Punnett Square to demonstrate the reasoning for your answer.
1 pt. Punnett:
1 pt. Reasoning:
3.
If a mom with type A blood had a child with type O blood, and the husband had type AB blood, can the husband be the father? Explain your reasoning and include Punnett Square proof.
Yes or No
1 pt. Explain
1 pt. Punnett Square Proof:
PLEIOTROPY:
Mrs. Loyd
 cloyd@waukee.k12.ia.us
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Sickle-cell anemia: The gene for this disorder causes anemia as well as many other serious problems. A single gene affects many characters.
4.
Use your book p.168, to describe how the sickle-cell gene can also cause kidney failure.
2pts.
POLYGENIC INHERITANCE: (Converse of Pleiotropy)
Phenotypes of a given trait that are controlled by more than one gene are described as having polygenic inheritance. Examples of polygenic inheritance in humans include height, weight, skin color, and intelligence. Some congenital malformations (birth defects) like clubfoot, cleft palate, or neural tube defects are also the result of multiple gene interactions.
Two pairs of genes (A and a, B and b) are responsible for ear length in corn. They are on different pairs of homologues. Possible phenotypic results are: longest, long, medium, short, shortest.
5.
Find the genotypic and phenotypic ratios in the F
1
if the pollen from a plant with the longest ear length is placed on the silk of a plant with shortest ear length.
You should approach these problems in the same was as two-trait crosses. The difference appears when expressing the phenotypes. While in a dihybrid cross, there are two characteristics, in polygenic inheritance there is only one characteristic but more variation.
1 pt. Parents = _______ x ________
1 pt. Genotype
1 pt. Phenotype
Find the phenotypic ratios of the F
2
.
1 pt. possible gametes:
(Punnett Square)
1 pt. Phenotypes:
6.
Do you think that two pairs of genes control human eye color? Explain. (Hint: How many phenotypes resulted for the length of corn ears? Is that enough to account for all eye colors?)
1pt
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