In pea plants, purple flowers are dominant to white flowers. If two white flowered plants are crossed. What percentage of their offspring will be white flowered? _
The correct answer and explanation is :
In pea plants, the flower color trait is governed by a simple Mendelian inheritance pattern, where purple flowers (P) are dominant to white flowers (p). When crossing two white-flowered plants, it is important to understand that both must have the genotype pp, as white flowers only appear when both alleles are recessive.
Step 1: Determine the genotypes of the parents
Since white flowers are recessive (p), both parent plants must be homozygous recessive for the flower color gene. Therefore, the genotype of both parent plants is pp.
Step 2: Perform the Punnett square analysis
A Punnett square is used to predict the genetic outcome of a cross. For the cross of two pp parents, the gametes from each parent can only carry the p allele (since both parents are pp). When these gametes combine during fertilization, the possible genotypes for the offspring will be:
| p | p | |
|---|---|---|
| p | pp | pp |
| p | pp | pp |
Step 3: Analyze the results
All offspring will inherit one p allele from each parent, resulting in a genotype of pp for every offspring. Since pp results in white flowers (as the recessive trait is expressed when two recessive alleles are present), 100% of the offspring will have white flowers.
Conclusion
Thus, 100% of the offspring from the cross of two white-flowered pea plants (pp x pp) will also have white flowers. This is because both parents contribute only the recessive allele p, resulting in the genotype pp for all offspring.
In summary, crossing two homozygous recessive white-flowered pea plants will result in 100% white-flowered offspring.