Gene Linkage: Same Chromosome

Correct Answer: Linked

When two genes governing two different traits are located on the same chromosome, they are said to be linked. Linked genes tend to be inherited together and violate Mendel's Second Law (Law of Independent Assortment).

Types of Linkage

• Complete linkage: Recombination frequency = 0 (e.g., male Drosophila, female silk moth, female poultry, sex chromosomes of all heterogametic species)
• Incomplete linkage: Recombination frequency between 0 and 0.5

Crossing Over

Crossing over = exchange of segments between non-sister chromatids of homologous chromosomes, occurring in the pachytene stage of Prophase-I of Meiosis-I. It is the 2nd biggest cause of genetic variation (after segregation).

Why Other Options Are Wrong

• Epistatic: Non-allelic gene interaction — not about chromosome location.
• Pleiotropic: One gene → multiple traits (e.g., sickle cell anemia gene in humans, halothane gene in pigs).
• Dominant: Describes allelic relationship at a single locus, not chromosomal location.