1.You are looking at a strain of rats that is doubly heterozygous for 2 genes th
ID: 10450 • Letter: 1
Question
1.You are looking at a strain of rats that is doubly heterozygous for 2 genes that are passed on through a dominant mode of inheritance. You mate two of these rats. What are the expected phenotypes of their offspring? Be sure to include ratios!2. A black guinea pig (BB) and a white guinea pig (bb) produce offspring. The pattern of inheritance for fur color in guinea pigs is codominance. Indicate the genotype and phenotype of all possible offspring.
3. You are breeding a new type of plant and studying traits for height, color, and seed shape. The alleles are as follow: H=tall, h=short; C=green, c=white; S=round, s=oval. In this plant the dominant alleles for height and color are linked, and the recessive alleles for height and color are linked. You cross a plant that is heterozygous at all gene loci with a plant that is homozygous recessive for height and color and heterozygous for seed shape. What will be the phenotypic ratios of their offspring?
Explanation / Answer
example
Bb Ee x Bb Ee
BE
Be
bE
be
BE
BE BE
bark Erect ears
BE Be
bark Erect ears
BE bE
bark Erect ears Erect ears
be BE
bark Erect ears
Be
BE Be
bark Erect ears
Be Be
bark
Be bE
bark Erect ears
be Be
bark
bE
BE bE
bark Erect ears
Be bE
bark Erect ears
bE bE
silent Erect ears
be bE
silent
- Erect ears -------
be
BE be
bark Erect ears
be Be
bark
be bE silent Erect ears
be be silent - dropping ears -------
Ratio -9:3:3:1
bark Erect ears-----9
bark dropping ears----3
silent Erect ears---3
silent - dropping ears----1
2. A black guinea pig (BB) and a white guinea pig (bb) produce offspring. The pattern of inheritance for fur color in guinea pigs is codominance. Indicate the genotype and phenotype of all possible offspring.
A black guinea pig (BB) and a white guinea pig (bb)
B
B
b
Bb
Bb
b
Bb
Bb
All offsprings are A black guinea pig genotyep---------Bb
3. You are breeding a new type of plant and studying traits for height, color, and seed shape. The alleles are as follow: H=tall, h=short; C=green, c=white; S=round, s=oval. In this plant the dominant alleles for height and color are linked, and the recessive alleles for height and color are linked. You cross a plant that is heterozygous at all gene loci with a plant that is homozygous recessive for height and color and heterozygous for seed shape. What will be the phenotypic ratios of their offspring?
Hh Cc Ss x hh cc ss
HC S h c s tall, green, round----------1/64
H Cs h c s tall, green, oval. -----
H cS h c s tall, white round----------
H cs h c s tall, white oval. -------
h CS h c s short, green, round--------
h Cs h c s short ,green, oval. -----
hcS h c s short, white round------------
h c s h c s short white oval. ----------1/64
BE
Be
bE
be
BE
BE BE
bark Erect ears
BE Be
bark Erect ears
BE bE
bark Erect ears Erect ears
be BE
bark Erect ears
Be
BE Be
bark Erect ears
Be Be
bark
Be bE
bark Erect ears
be Be
bark
bE
BE bE
bark Erect ears
Be bE
bark Erect ears
bE bE
silent Erect ears
be bE
silent
- Erect ears -------
be
BE be
bark Erect ears
be Be
bark
be bE silent Erect ears
be be silent - dropping ears -------
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