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?

Question

If a plant has purple 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.
If a plant has purple flowers, then its genotype must be PP .

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 white flowers, then its genotype must be Pp.
If a plant has white flowers, then its genotype must be Pp .

Answer 1

In pea plants, where the allele for purple flowers (P) is dominant over the allele for white flowers (p), we can derive the following conclusions about phenotype and genotype:

1. If a plant has purple flowers, then its genotype must be Pp. - This statement is not correct. A plant with purple flowers could either be homozygous dominant (PP) or heterozygous (Pp).

2. If a plant has purple flowers, then its genotype must be PP. - This statement is also not correct. As mentioned earlier, a plant with purple flowers could be either PP or Pp.

3. If a plant has white flowers, then its genotype must be pp. - This statement is correct. Since the white flower phenotype only occurs with the homozygous recessive genotype (pp), any plant with white flowers must have the genotype pp.

4. If a plant has white flowers, then its genotype must be Pp. - This statement is not correct. A plant with white flowers cannot have a Pp genotype, as that would result in a purple flower phenotype due to the presence of the dominant allele.

In summary, the only conclusion that can be confidently made is:

• If a plant has white flowers, then its genotype must be pp.