A true-breeding, purple-flowered pea plant is crossed with a white-flowered plant. They produce two `F_(1)` progeny that are then mated with each other to yield `10 F_(2)` plants. The `F_(1)` contains 5 purple-flowered plants and 5 white-flowered plants. Which of the following is the best explanation for the `F_(2)` results?

Options

A. They are exactly what is expected from Mendel's laws.
B. They are similar to, but not exactly, what Mendel's laws predict.
C. They are rather different from predictions, probably due to small sample size.
D. The `F_( 1)` plants must have suffered a mutation before mating.

Answer

To solve the question regarding the inheritance of flower color in pea plants, we can follow these steps:

### Step 1: Understand the Parental Generation
- We start with a true-breeding purple-flowered pea plant (let's denote the purple allele as "P") and a white-flowered plant (denote the white allele as "p").
- The true-breeding purple plant has the genotype "PP" while the white-flowered plant has the genotype "pp".

### Step 2: Determine the F1 Generation
- When these two plants are crossed, all offspring (F1 generation) will inherit one allele from each parent.
- Therefore, all F1 progeny will have the genotype "Pp", which expresses the dominant purple phenotype.

### Step 3: Cross the F1 Generation
- The F1 plants (Pp) are then mated with each other to produce the F2 generation.
- The possible combinations of alleles in the F2 generation can be determined using a Punnett square.

### Step 4: Analyze the F2 Generation
- The Punnett square for a cross between two Pp plants will yield the following genotypes:
- 1 PP (purple)
- 2 Pp (purple)
- 1 pp (white)
- This results in a phenotypic ratio of 3 purple-flowered plants to 1 white-flowered plant.

### Step 5: Evaluate the F2 Results
- In this scenario, we have 10 F2 plants, which resulted in 5 purple-flowered plants and 5 white-flowered plants.
- This gives a phenotypic ratio of 1:1, which is not what we would expect from a typical 3:1 ratio.

### Step 6: Conclusion
- The best explanation for the observed 1:1 ratio in the F2 generation is due to the small sample size of 10 plants.
- With a small sample size, the results can deviate from the expected Mendelian ratios, leading to the observed equal numbers of purple and white flowers.

### Final Answer
The best explanation for the F2 results (5 purple and 5 white) is that the sample size is too small, leading to a deviation from the expected 3:1 ratio.

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