In a certain plant,when individuals with blue flowers are crossed with individuals with blue flowers,only blue flowers are produced.Plants with red flowers crossed with plants with red flowers sometimes produce only red flowers,although other times they produce either red or blue flowers.When plants with red flowers are crossed with plants with blue flowers,sometimes only red flowers are produced; other times either red or blue flowers are produced.Which of the following is true?
A) Red is dominant
B) Blue is dominant
C) Red is recessive
D) Red is codominant
E) Red is incompletely dominant

Question

In a certain plant,when individuals with blue flowers are crossed with individuals with blue flowers,only blue flowers are produced.Plants with red flowers crossed with plants with red flowers sometimes produce only red flowers,although other times they produce either red or blue flowers.When plants with red flowers are crossed with plants with blue flowers,sometimes only red flowers are produced; other times either red or blue flowers are produced.Which of the following is true?  
A) Red is dominant
B) Blue is dominant
C) Red is recessive
D) Red is codominant
E) Red is incompletely dominant

Quizplus · Accepted Answer

BThe fact that blue flowers only produce blue flowers when crossed with each other suggests that blue is a recessive trait, as it appears consistently without variation. However, the presence of red flowers from crosses between red and blue flowered plants, as well as the variability in the offspring of red flowered plants (sometimes producing only red, other times both red and blue), suggests that red is a dominant trait. This scenario does not fit the definitions of codominance or incomplete dominance, as those would result in a mixture or blending of traits, which is not described. Therefore, both A and B are correct because they reflect the dominance of red over blue and the recessive nature of blue, which can only express itself when two copies are present.

In a Certain Plant,when Individuals with Blue Flowers Are Crossed