Example of Overdominance
If $AA=10$ & $aa=0$, then which of the following is the example of Overdominance--
- $Aa=5$
- $Aa=7$
- $Aa=10$
- $Aa=15$ — Correct Answer
Explanation:
Correct Answer: Aa = 15 (Overdominance)
In overdominance, the heterozygote (Aa) shows a phenotypic value superior to BOTH homozygotes (AA and aa). Since AA = 10 is the highest homozygote, the heterozygote must exceed 10 to show overdominance. Aa = 15 > AA = 10 ✓.
Complete Comparison — All Gene Action Types (when AA=10, aa=0)
| Aa Value | Type of Gene Action | Rule |
|---|---|---|
| Aa = 5 | Additive gene action | Aa = midpoint of AA and aa (10+0)/2 = 5 |
| Aa = 7 | Incomplete (partial) dominance | 5 < Aa < 10 (between midpoint and dominant) |
| Aa = 10 | Complete dominance | Aa = AA (dominant fully masks recessive) |
| Aa = 15 | Over-dominance | Aa > AA (heterozygote exceeds both homozygotes) |
Overdominance is the basis of heterosis (hybrid vigour).
📚 About this Topic — Animal Genetics & Breeding
This multiple choice question is from Animal Genetics & Breeding, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Genetics & Breeding to strengthen your preparation.
