In a population of parent pea plants, the frequency of the red- ower color allel

Question

In a population of parent pea plants, the frequency of the red- ower color allele (R) is 0.7 and the frequency of the white ower color allele (r) is 0.3. The red allele (R) is dominant to the white allele (r). Assume that two alleles are passed down independently from two parent plants to their offspring. In other words, the probability that a randomly chosen parent plant will pass an R-allele down to its ospring is 0.7 and the probability that the plant will pass down an r-allele is 0.3. (a) What is the probability that an offspring plant has genotype Rr? (b) What is the probability that an offspring plant has red owers? (c) What is the probability that a plant with red flowers in the parent generation will pass on an R allele to its offspring? (d) A parent pea plant with red flowers and known genotype Rr is bred to an- other parent pea plant with red flowers but unknown genotype. What is the probability that these two plants will have an offspring of genotype RR?

Explanation / Answer

A) Probability of Rr genotype = 0.7x0.3 + 0.3x0.7 = 0.42

B) P(an offspring having red owers) = P(Rr) + P(RR) = 0.42 + 0.7x0.7 = 0.91

C) P(R is passed to offspring | parent is having red flowers) = probability of R being passed from RR or Rr

= 3/4

D) P(RR offspring) = 0.5xP(RR ofspring from Rr and RR) + 0.5xP(RR offspring from Rr and Rr)

= 0.5x (0.5x1) + 0.5(0.5x0.5)

= 0.375

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