Question

Part A: Crossing lines with the same recessive phenotype

You continue your analysis by crossing the Aberdeen White and Victoria White lines. This time you count the actual numbers of progeny in the two F2 phenotypic classes.

Part B: Crossing lines with dissimilar recessive phenotypes
You continue your analysis by crossing the Aberdeen White and Kansas Yellow lines. Again, you count the actual numbers of progeny in the two F2 phenotypic classes.

Part C: A second cross between lines with dissimilar phenotypes
You complete your analysis by crossing the Victoria White and Kansas Yellow lines. Again, you count the actual numbers of progeny in the F2 phenotypic classes.

Part D: Assembling a genetic model
Based on your analysis so far, you assign the following allele symbols to the three lines:
Wild type = A_ V_
Aberdeen White = a a
Kansas Yellow = aYaY
Victoria White = v v

Answer 1

The question revolves around Mendelian genetics and crossing lines to determine the offspring's genotypes and phenotypes using Punnett squares, focusing on monohybrid and dihybrid crosses with dominant and recessive traits.

Step-by-step explanation:

The student's question pertains to Mendelian genetics, particularly the analysis of crossing lines with different phenotypes using Punnett squares to predict the genotypes and phenotypes of the progeny in the F2 generation. A monohybrid cross involves two parents with different alleles for a single trait, and when true-breeding parents are crossed (YY and yy, for dominant yellow and recessive green pea seeds), all F1 offspring will have the heterozygous genotype (Yy) and the dominant phenotype (yellow seeds).

In Punnett square analysis, the genotypic ratio in F2 from a cross of two Yy parents is expected to be 1:2:1 (YY:Yy:yy), leading to a phenotypic ratio of 3 yellow:1 green, due to the dominance of the yellow seed allele. The 9:3:3:1 dihybrid ratio observed in parents with two different traits can be simplified into two separate 3:1 monohybrid ratios, assuming the traits are assorted independently.