In the flowering plants (the angiosperms),the process of double fertilization occurs.This is where one sperm nucleus from the pollen grain fertilizes the egg,and the other fuses with the two polar nuclei in the female gametophyte to produce the triploid (3n)endosperm tissue.The aleurone layer (the outer layer of cells of the endosperm)can be colored or colorless.The allele C causes color (purple),and the allele c gives colorless aleurone.A plant is of genotype Cc and self-pollinates.What ratio of colored to colorless aleurone layered endosperms are expected in the progeny?
A)1:1
B)2:1
C)3:1
D)10:1

Question

Quizplus · Accepted Answer

Since the plant is Cc, it means it is heterozygous for the aleurone layer color. When it self-pollinates, the possible gametes it can produce are C and c in equal frequency. The Punnett square for this cross would be:
 
        C   c
    C| CC  Cc
    c| Cc  cc

As we can see, there is a 3:1 ratio of colored (CC and Cc) to colorless (cc) aleurone layer endosperms in the progeny. Therefore, the answer is choice C.

In the Flowering Plants (The Angiosperms),the Process of Double Fertilization