Question

Q13 A group of students are studying flower color inheritance in the garden pea plant. They obtain a purple-flowered pea plant of unknown ancestry, allow it to self-pollinate, and collect 60 of its seeds. After planting the seeds, they observe the growth of 42 purple- flowered plants and 18 white-flowered plants. Which of the following best explains the flower colors seen in the offspring? A Purple flowers and white flowers are codominant B. White flower color is a trait recessive to purple flower color C. The flower color changes as the plants mature D. A somatic mutation in the flower color gene produced the white flower color​

Answer 1

correct option will be B. White flowers color is a trait recessive to purple flower

Explanation:

• By selfing Purple flowered plants, 60 seeds generate. Among them 42 are purple flowered and 18 white flowered.
• It is a monohybrid cross.
• observed ratio is Purple flower : white flower = 42 : 18 = 2.8 : 1.2 ≈ 3 : 1
• Observed ratio is equal to expected ratio of mendelian monohybrid cross.
• In mendelian monohybrid ratio, Dominant phenotype : recessive phenotype= 3 : 1
• So the purple color is dominant over white color.
• If Purple color gene is R and white color gene is r. genotype of Purpled flower plant can be Rr or RR and genotype of white plant is rr.
•                                Rr ×  Rr

                                 R                        r

                         R    RR                      Rr

                         r     Rr                       rr

• so the ratio of purple flower plant(RR or Rr) : white flower plant(rr)=3:1
• so, white flower is recessive to purple flower.