Question

Recall Mendel's pea plants: the allele for purple flowers, P, is dominant to the allele for white flowers, p. A very large number of offspring from a cross of two plants are observed. If ALL of those offspring have purple flowers, what are the possible genotypes of the parents in the cross?

A. PP × PP only
B. PP×PP, PP×Pp, or PP x pp
C. PP×PP, PP×Pp, PP x pp, or Pp x Pp
D. pp×pp only
E. Not enough information is given

Answer 1

pp

Step-by-step explanation:

Answer 2

B. PP×PP, PP×Pp, or PP x pp

Step-by-step explanation:

The allele for the purple flower (P) is dominant over the one for the white flowers (p). To be a purple-flowered plant, the progeny must have homozygous dominant (PP) or heterozygous dominant (Pp). A cross between two homozygous dominant purple-flowered parents (PP x PP) would produce all the homozygous dominant progeny (PP) having purple flowers.

A cross between a homozygous dominant (PP) and a heterozygous dominant (Pp) parent plant would produce homozygous and heterozygous dominant progeny in a 1:1 ratio (PP x Pp = 1 PP: 1 Pp). Similarly, a cross between a homozygous dominant (PP) and homozygous recessive (pp) parent plant would produce all heterozygous dominant (Pp) progeny with purple flowers.