Zero Recombination Frequency
If recombination or crossing-over frequency is zero, then it is:
- Complete linkage — Correct Answer
- Incomplete linkage
- Partial linkage
- No linkage
Explanation:
Correct Answer: Complete linkage
When two genes are located so close together on the same chromosome that no crossing over ever occurs between them, the recombination frequency = 0. This is called Complete linkage — they are always inherited together as a single, inseparable unit.
Types of Linkage — Comparison
| Type | Recombination Frequency | Condition |
|---|---|---|
| Complete linkage | = 0 (0%) | No crossing over between the two genes |
| Incomplete / Partial linkage | 0 < RF < 0.5 (0–50%) | Some crossing over occurs; genes partially linked |
| No linkage (Independent assortment) | = 0.5 (50%) | Genes on different chromosomes OR very far apart |
Key Note on Crossing Over
- Crossing over occurs at the Pachytene stage of Prophase-I of Meiosis-I, between non-sister chromatids of homologous chromosomes.
- Crossing over is the 2nd largest cause of genetic variation after segregation.
📚 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.
