x-y: 2.6%, y-z: 1.4% and x-z: 1.2%. Then the gene order is

1. x-z-y
2. x-y-z
3. y-x-z
4. z-x-y

   Determining Gene Order from Recombination Frequencies: x-y 2.6%, y-z 1.4%, x-z 1.2%

   Recombination frequencies help map gene order on chromosomes, with lower percentages indicating closer proximity. For genes x, y, and z showing x-y: 2.6%, y-z: 1.4%, and x-z: 1.2%, the correct sequence follows the additive distance principle where the sum of smaller intervals matches the largest observed frequency.​

   Correct Answer

   x-z-y

   In this order, x to z is 1.2%, z to y is 1.4%, and their sum (1.2% + 1.4% = 2.6%) exactly matches the x-y frequency, confirming z lies between x and y.​

   Option Analysis

   Option	Predicted Frequencies	Matches Data?	Explanation
   x-z-y	x-z: 1.2%, z-y: 1.4%, x-y: 2.6%	Yes	Additive: 1.2 + 1.4 = 2.6%; all observed values align perfectly ​.
   x-y-z	x-y: 2.6%, y-z: 1.4%, x-z: 4.0%	No	x-z should be 2.6 + 1.4 = 4.0%, but observed is 1.2% ​.
   y-x-z	y-x: 2.6%, x-z: 1.2%, y-z: 3.8%	No	y-z should be 2.6 + 1.2 = 3.8%, but observed is 1.4% ​.
   z-x-y	z-x: 1.2%, x-y: 2.6%, z-y: 3.8%	No	z-y should be 1.2 + 2.6 = 3.8%, but observed is 1.4% ​.

   Key Mapping Principle

   The gene order positions the two closest genes (lowest frequency) as adjacent, with the middle gene splitting the farthest pair additively. Here, x-z (1.2%) is lowest, followed by y-z (1.4%), placing z centrally. This method ensures no discrepancies in three-gene linkage analysis.​