I have read the chapter in my textbook twice and attempted multiple questions si
ID: 142084 • Letter: I
Question
I have read the chapter in my textbook twice and attempted multiple questions similar to this and I am still very lost. If possible, please please include your thought process in your answer. I barely have any understanding of these kind of pathway questions and it's spooking me. Thank you for your help
31) True breeding white flowering plants are crossed to true breeding red flowering plants. The offspring are red flowered. When these flowers are self crossed, the resultant offspring are 87 red, 32 pink and 39 white flowered plants. Which of the following pathways is most likely the cause of this B. pink -A--->pink---B--->red C. redred D. white -Apink white Bpink both genes producing pink together give redExplanation / Answer
Answer is pathway A
White----A----> Pink -------B------> red
This is an example of an incomplete or partial dominance. which says that when a cross between parents with contrasrin traits may generate off spring with an intermediate phenotype.
Let us consider
White =R1R1, Pink =R2R2 and Red=R1 R2
White R1R1 is crossed with red R1R2
R1R2*R1R2
R1R1=1=39 White flowers
R1R2=2=Red flowers
R2R2=1=Pink flowers
The genotype ratio is 1:2:1. Here neither allele is dominant , the phenotype ratio is identical to the genotypic ratio. So, white flowers crossing with pink flowers gives rise to Red flowers.Red is heterozygous and partial dominant flowers influenzed by both contrasting taist that is white and pink to give red flowers.When white homozygous is crossed with Red heterozygous e get 1:2:1 ratio of monohybrid cross. When it is self crossed that is red * red we get the partial dominance.