Question

A crossing of two or more breeds and alternately mating the hybrid females over several generations with males of the original breeds is called

• A. Criss crossing
• B. Back crossing
• C. Test crossing
• D. Out crossing

Hint:

To remember criss-crossing, think of "criss-cross" as alternating back and forth between two parental breeds to sustain a high level of maternal heterosis in successive generations.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Crossbreeding is an essential mating system in animal breeding where individuals of different breeds or populations are mated.
It is designed to exploit breed complementarity and maximize heterosis (hybrid vigor) in successive generations.

Step 2: Detailed Explanation:
Let us analyze the definitions of the terms provided in the options:
- Criss-crossing (Rotational Crossing with two breeds): This is a systematic crossbreeding program.
In this system, two breeds (say, Breed A and Breed B) are mated to produce an $F_1$ hybrid female.
These hybrid females are then mated to a purebred male of Breed A.
The resulting female offspring are mated to a purebred male of Breed B, and this alternate mating pattern continues over several generations.
Thus, the hybrid females are mated alternately with the males of the original parental breeds.
- Backcrossing: This refers to crossing a hybrid with one of its parents or genetically identical individuals to achieve a high concentration of the parent's genes.
- Test crossing: This is a diagnostic cross in genetics where an individual of unknown genotype showing a dominant phenotype is crossed with a homozygous recessive individual to determine its zygosity.
- Out crossing: This refers to mating unrelated animals within the same pure breed.
Therefore, the correct term for the alternate mating of hybrid females to parental males over generations is criss-crossing.

Step 3: Final Answer:
The described crossbreeding system is called Criss-crossing.