I hope you like the movie “Charlie and the Chocolate Factory” as much as I do. Oompa Loompa Genetics: Oompa Loompas generally have blue faces, which is caused by a dominant gene. The recessive condition results in an orange face. Otis Oompa has an orange face and is married to Ona Oompa, who has a blue face. They have 60 children, 30 of whom have orange faces. What are the genotypes of the parents? A. BB and BB B. bb and BB C. bb and Bb D. bb and bb
The Correct Answer and Explanation is:
The correct answer is C. bb and Bb.
Explanation:
In this scenario, face color in Oompa Loompas follows simple Mendelian genetics:
- B = Dominant allele for blue face
- b = Recessive allele for orange face
An individual with:
- BB = Blue face
- Bb = Blue face (carrier of orange face gene)
- bb = Orange face
Otis Oompa has an orange face, meaning his genotype is bb.
Ona Oompa has a blue face, but half of their children have orange faces, meaning Ona must be carrying the recessive gene. So, Ona’s genotype is Bb.
Let’s confirm this with a Punnett square:
| B | b | |
|---|---|---|
| b | Bb | bb |
| b | Bb | bb |
Results:
- 50% Bb (Blue face)
- 50% bb (Orange face)
From their 60 children:
- 30 blue faces (Bb)
- 30 orange faces (bb)
This matches the data provided: 30 children have orange faces, showing a 50% orange face ratio, consistent with a bb × Bb parental cross.
Why Other Choices Are Incorrect:
- A. BB and BB: All offspring would have BB genotype, all blue faces, impossible in this case.
- B. bb and BB: All offspring would be Bb, all blue faces, no orange-faced children.
- D. bb and bb: All offspring would be bb, all orange faces, but half the children have blue faces, so this is incorrect.
Conclusion:
The parents are bb (Otis, orange face) and Bb (Ona, blue face carrier), matching answer C. bb and Bb.
