Example of Additive Gene Action
If $AA=10$ & $aa=0$, then which of the following is the example of Additive gene action-
- $Aa=5$ — Correct Answer
- $Aa=7$
- $Aa=10$
- $Aa=15$
Explanation:
Correct Answer: Aa = 5 (Additive gene action)
In additive gene action, there is zero dominance — each allele contributes independently and equally. The heterozygote (Aa) falls exactly at the mid-parent value: (AA + aa)/2 = (10 + 0)/2 = 5.
Significance of Additive Gene Action
- Additive gene action is the basis of heritability in the narrow sense (h²ɴ = VA/VP).
- It underlies polygenic inheritance, GCA, and resemblance between relatives.
- Traits with high additive variance respond well to individual selection.
- Inbreeding depression does NOT occur for traits governed purely by additive gene action.
All Gene Action Types Summary (AA=10, aa=0)
| Aa | Gene Action |
|---|---|
| 5 | Additive (no dominance) |
| 7 | Incomplete dominance |
| 10 | Complete dominance |
| 15 | Over-dominance |
📚 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.
