A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish Dwarf produces a short plant with white seed. The two varieties are crossed, and the resulting seeds are collected. All of the seeds are white; and when planted, they produce all tall plants. These tall F₁ plants are allowed to self-fertilize. The results for seed color and plant stature in the F₂ generation are as follows:
   F₂ Plant Phenotype    Number
   Blue seed, tall plant.     97
   White seed, tall plant   270
   Blue seed, short plant    33
   White seed, short plant  100
  TOTAL                500


What is the expected distribution of phenotypes in the F₂ generation?

Verified step by step guidance

1. Step 1: Identify the parental phenotypes and genotypes. The Blue Persian variety produces tall plants with blue seeds, while the Spanish Dwarf variety produces short plants with white seeds. Assume that tall (T) is dominant to short (t) and white seeds (W) are dominant to blue seeds (w).
2. Step 2: Analyze the F₁ generation. The cross between the two parental varieties results in all tall plants with white seeds. This suggests that the F₁ generation is heterozygous for both traits (TtWw), as the dominant traits (tall and white) are expressed.
3. Step 3: Predict the F₂ generation using a dihybrid cross. Perform a Punnett square for the two traits (Tt x Tt for plant height and Ww x Ww for seed color). This will result in a 9:3:3:1 phenotypic ratio for the F₂ generation, assuming independent assortment.
4. Step 4: Assign the phenotypes to the expected ratios. The 9:3:3:1 ratio corresponds to the following phenotypes: 9 tall plants with white seeds, 3 tall plants with blue seeds, 3 short plants with white seeds, and 1 short plant with blue seeds.
5. Step 5: Calculate the expected numbers for each phenotype. Multiply the total number of F₂ plants (500) by the proportions from the 9:3:3:1 ratio. For example, the expected number of tall plants with white seeds is (9/16) * 500, and so on for the other phenotypes.

Key Concepts

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations, based on the principles established by Gregor Mendel. It involves understanding dominant and recessive alleles, where dominant traits mask the expression of recessive ones. In this scenario, the tall plant and white seed traits are likely dominant, influencing the phenotype ratios observed in the F₂ generation.

Phenotypic Ratios

Phenotypic ratios represent the relative frequencies of different phenotypes in a given generation. In Mendelian inheritance, the F₂ generation typically exhibits a 9:3:3:1 ratio for two traits when both parents are heterozygous. Analyzing the provided data will help determine if the observed ratios align with expected Mendelian ratios, indicating the inheritance patterns of the traits.

Genotype and Phenotype

The genotype refers to the genetic makeup of an organism, while the phenotype is the observable expression of that genotype influenced by environmental factors. In this case, the F₁ generation's genotype leads to tall plants, but the F₂ generation reveals a variety of phenotypes, indicating the segregation of alleles and the interaction between different traits, such as seed color and plant height.