Question:
Given below are two statements:
Statement I: Breed is maintained through grading of animals
Statement II: Heterosis is stabilized in the 3rd generation of mating
In the light of the above statements, choose the most appropriate answer from the options given below
Given below are two statements:
Statement I: Breed is maintained through grading of animals
Statement II: Heterosis is stabilized in the 3rd generation of mating
In the light of the above statements, choose the most appropriate answer from the options given below
Statement I: Breed is maintained through grading of animals
Statement II: Heterosis is stabilized in the 3rd generation of mating
In the light of the above statements, choose the most appropriate answer from the options given below
Show Hint
Breeding Concepts:
Grading Up $\rightarrow$ Converts scrub females to purebreds in 5--7 generations.
Heterosis $\rightarrow$ Maximum in $F_1$, declines in $F_2/F_3$ (CANNOT be fixed/stabilized in advanced generations).
Grading Up $\rightarrow$ Converts scrub females to purebreds in 5--7 generations.
Heterosis $\rightarrow$ Maximum in $F_1$, declines in $F_2/F_3$ (CANNOT be fixed/stabilized in advanced generations).
Updated On: Sep 7, 2026
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is correct but Statement II is false
- Statement I is incorrect but Statement II is true
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Animal breeding systems: grading up is used to convert non-descript stock into purebreds, and heterosis (hybrid vigor) is maximal in the F1 generation and disperses in subsequent generations due to segregation.
Key Formula or Approach:
\[ \text{Grading Up: Non-descript } \xrightarrow{\text{Purebred Sires } 5-7 \text{ Generations}} \text{Purebred Stock (98.4\% Pure)} \]
\[ \text{Heterosis } (H) \text{ is MAXIMAL in } F_1 \text{ and HALVES in } F_2 \text{ due to gene segregation} \]
Step 2: Detailed Explanation:
1. Statement I: Grading Up is a continuous breeding system where non-descript/scrub females are mated for 5 to 7 consecutive generations to purebred sires of a specific breed to grade up and transform non-descript animals into near-purebred stock (reaching $98.4\%$ breed inheritance), NOT to maintain an existing pure breed (which is maintained by pure breeding/linebreeding). Hence, Statement I is false.
2. Statement II: Heterosis (Hybrid Vigor) is non-additive genetic variance that is maximal in the $F_1$ generation; in the $F_2$ and 3rd generations, segregation and recombination break up epistatic combinations, halving and dissipating heterosis, never stabilizing it. Hence, Statement II is false.
Step 3: Final Answer:
Hence, Both Statement I and Statement II are false, corresponding to option (B).
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