Question

A self-pollinating plant with orange flowers and alternating leaf arrangement produces
Plants with red flowers and alternating leave- 47
Plants with orange flowers and alternating leaves- 103
Plants with yellow flowers and alternating leaves- 51

Suppose the original parent plant is cross-pollinated with a plant that has red flowers and non-alternating leaves. All of the resulting offsprings have non-alternating leaves. Which of the following is/are true?

• A. None of the offsprings have orange flowers.
• B. The allele for alternating leaves is recessive.
• C. Approximately half of the offsprings have red flowers.
• D. Both A and B.
  
• E. Both B and C.
  

Answer 1

The correct option is E Both B and C.

Since the $F_2$ generation of the monohybrid cross is showing the phenotypic ratio of 1:2:1, it is an example of incomplete dominance. Yellow flower (Y) allele is incompletely dominant over that of red flower (y) while allele of leaf arrangement shows complete dominant recessive relation. The genotype of original parent plant is homozygous for leaf arrangement and heterozygous dominant for flower color (Yy). A cross between original parent plant and plant with red flowers and non-alternating leaves will have the orange flower as the heterozygous dominant genotype "Yy" will exhibit orange phenotype. All of the resulting offsprings have non-alternating leaves means alternate allele is recessive and is masked by the presence of nonalternate allele. Looking at the cross, the correct answer is option E.

Yyaa----> yyAA	Ya	ya
yA	YyAa Orange flowers and non-alternating leaves	aaAa Red flowers and non-alternating leaves