2) Based on the pedigree shown here (which represents the color of flowers in pe

Question

2) Based on the pedigree shown here (which represents the color of flowers in pea plants), which allele for flower color (white or purple) is dominant and how do you know?

3. (a) (0.5 point) Using what you know from Question 2, and using whatever symbols you like, list the possible genotype(s) of a purple-flowered pea plant.

(b) (0.5 point) If you perform a test cross on the plant in part (a), what would be the genotype and phenotype of the second parent in the test cross? Why must the second parent have this specific genotype?

4. (1 point) In another corn-genetics experiment, you cross a plant A (which grew from a purple and smooth kernel) with plant B (which grew from a yellow and wrinkled kernel). The F1 generation kernels are counted: 122 kernels are purple and wrinkled, and 117 kernels are purple and smooth. What is the genotype of plant A?

5. (1 point) The dominant T allele prevents tail formation in cats. A cat with a tt genotype has a normal tail. A TT cat embryo dies early in embryogenesis. Predict the outcome of a cross between two tailless cats. List all the possible phenotypes and the expected percentages of the kittens that will be born.

6. In cats, the B gene controls hair color (the dominant B allele = black, and the recessive b allele = brown).

The S gene controls spotting (the dominant S allele = white spots, and the recessive s allele = no spots).

The D gene controls the density of hair pigment. The recessive d allele allows the full color of the B and b alleles to show. The dominant D allele dilutes the color so that black color becomes gray, and brown color becomes tan.

(0.5 point each) For each cat shown below, identify the possible genotype(s) for the B, S, and D genes.

black with white spots, gray, brown with white spots, tan

Explanation / Answer

4. PPSs

5. Out of the four cases, one will be non-viable (TT), two will be tailless (Tt) and one will be normal (tt)

6. Black with white spots: BB or Bb, SS or Ss, dd

Brown with white spots: bb, SS or Ss, dd

Tan: bb, ss, Dd or DD

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