the punnett square above shows a cross between two sweet pea plants in mendels greenhouse. both parents have…
the punnett square above shows a cross between two sweet pea plants in mendels greenhouse. both parents have blue flowers (bb). which statement describes the offspring expected from this cross? a 50% white - flowered and 50% blue - flowered b 75% white - flowered and 25% blue - flowered c 75% blue - flowered and 25% white - flowered d 100% blue - flowered and 0% white - flowered
Answer
Explanation:
Step1: Set up the Punnett - square cross
The parents are both Bb. The possible gametes from each parent are B and b. When we set up the Punnett - square, we have the following combinations:
| B | b | |
|---|---|---|
| B | BB | Bb |
| b | Bb | bb |
Step2: Analyze the genotypes and phenotypes
BB and Bb genotypes result in blue - flowered plants because B is the dominant allele for blue flowers. The bb genotype results in white - flowered plants. There is 1 BB, 2 Bb, and 1 bb. So, the ratio of blue - flowered (BB + Bb) to white - flowered (bb) is 3:1. The percentage of blue - flowered plants is $\frac{3}{4}\times100% = 75%$, and the percentage of white - flowered plants is $\frac{1}{4}\times100%=25%$.
Answer:
C. 75% blue - flowered and 25% white - flowered