In pea plants, the allele for purple flowers, P, is dominant over the allele for white flowers, p. Which conclusion about phenotype and genotype is possible?
If a plant has white flowers, then its genotype must be Pp .
If a plant has white flowers, then its genotype must be pp .
If a plant has purple flowers, then its genotype must be Pp .
If a plant has purple flowers, then its genotype must be PP.
The correct conclusion is: If a plant has purple flowers, then its genotype must be Pp. This is because the allele for purple flowers (P) is dominant over the allele for white flowers (p), meaning that even if an individual has one allele for purple flowers and one allele for white flowers, it will still express the purple flower phenotype. The genotype PP would result in purple flowers as well, but it is not the only possible genotype for individuals with purple flowers.
The correct conclusion about phenotype and genotype based on the given information is:
If a plant has white flowers, then its genotype must be pp.
The correct conclusion is: If a plant has purple flowers, then its genotype must be Pp.
To understand why this conclusion is correct, we need to understand the concept of dominance in genetics. In this case, the allele for purple flowers (P) is dominant over the allele for white flowers (p). This means that if an organism carries at least one dominant allele (P), it will exhibit the corresponding dominant phenotype (purple flowers), regardless of whether it also carries a recessive allele (p). In contrast, the recessive phenotype (white flowers) will only be expressed if an organism carries two copies of the recessive allele (pp).
Let's go through each option to see which ones are possible conclusions:
1. If a plant has white flowers, then its genotype must be Pp.
This conclusion is incorrect. If a plant has white flowers, it means it is expressing the recessive phenotype. According to the rules of dominance, the plant must have two copies of the recessive allele (pp) to exhibit the white flower phenotype.
2. If a plant has white flowers, then its genotype must be pp.
This conclusion is correct. If a plant has white flowers, it means it is expressing the recessive phenotype, which requires having two copies of the recessive allele (pp).
3. If a plant has purple flowers, then its genotype must be Pp.
This conclusion is correct. If a plant has purple flowers, it means it is expressing the dominant phenotype, which can be achieved by having at least one copy of the dominant allele (P). In this case, the genotype can be either PP or Pp.
4. If a plant has purple flowers, then its genotype must be PP.
This conclusion is incorrect. While plants with purple flowers can have the genotype PP, they can also have the genotype Pp. The dominant phenotype (purple flowers) can be expressed with either one or two copies of the dominant allele (P).
Therefore, the correct conclusion is: If a plant has purple flowers, then its genotype must be Pp.