4) A vanilla bean plant with w
4) A vanilla bean plant with white-coloured flowers wasself-crossed. The seeds were collected and planted. The resultingprogeny were 211 plants with white-coloured flowers and 55 plantswith black-coloured flowers.
Write the genotypes of the parentalplant and its progeny, using B and b to designate the differentflower-colour alleles.
(a) Genotype of the parent withwhite-coloured flowers:
(b) Genotype(s) ofthe progeny with white-coloured flowers (if more than one genotypeis possible, please separate the genotypes with a comma and aspace,
e.g. BB,Bb, bb):
(c) Genotype(s) of theprogeny with black-coloured flowers (if more than one genotype ispossible, please separate the genotypes with a comma and a space,e.g. BB, Bb, bb):
Predict the phenotypic ratios forthe crosses shown below: HINT: Use thegenotypes you predicted above in Question 4 to assist you.
| cross | whitecolor flower | black color flowers |
| Parental white-flowered plant self-crossed | ||
| Parental white-flowered plant crossed with a black-floweredplant from the F1 generation | 3:1 | |
| Pure-breeding white-flowered plant crossed with a parentalwhite-flowered plant | ||
| Pure-breeding white-flowered plant test-crossed | ||
| Pure-breeding black flowered plant crossed with ablack-flowered plant from the F1 generation |
Answer:
Parent plant: It must be heterozygote as its progeny showssegregation of phenotype.Genotype of the parent plant = BbPhenotype = White flowers (Dominant phenotype)Recessive phenotype = Black flowers
Parental cross: Bb X BbProgeny: BB (White) Bb Bb (White) bb (Black)Genotypic ratio = 1:2:1Phenotypic ratio = 3 (White): 1 (Black)
Genotype of the progeny plants with white flowers = BB orBbGenotype of the progeny plants with black flowers = bb
a. Parental white-flowered plants selfed = Bb X BbProgeny: BB (White) Bb Bb (White) bb (Black)Genotypic ratio = 1:2:1Phenotypic ratio = 3 (White): 1 (Black)
b. Parental white-flowered plant crossed with black plants = BbX bbProgeny: BB (White) Bb (White) bb (Black)Genotypic ratio = 1:1Phenotypic ratio = 1 (White): 1 (Black)
c. Pure breeding white-flowered plant crossed with parentalwhite-flowered plants = BB X BbProgeny: BB (White) Bb (White)Genotypic ratio = 1:1Phenotypic ratio = 1 (All white)
d. Pure breeding white-flowered plants test crossed = BB XbbProgeny: Bb (White)Genotypic ratio = 1Phenotypic ratio = 1 (All white)
e. Pure breeding black-flowered plants crossed with blackflowered plants from F1 = bb X bbProgeny: bb (Black)Genotypic ratio = 1Phenotypic ratio = 1 (All black)
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