Question

Pure line breed refers to:

• A. Heterozygosity
• B. Homozygosity
• C. Homozygosity and self-assortment
• D. Heterozygosity and linkage

Hint:

Continuous selfing/inbreeding \(\rightarrow\) Homozygosity \(\rightarrow\) Pure lines.
Continuous outcrossing \(\rightarrow\) Heterozygosity.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In genetics and plant breeding, a "pure line" represents a progeny of a single self-fertilized, homozygous plant.

Step 2: Detailed Explanation:
When plants are repeatedly self-pollinated (or inbred) over several generations, the proportion of heterozygous loci decreases by \(50\%\) in each generation.
Ultimately, this results in complete homozygosity.
Thus, a pure line breed or variety consists of individuals that are genetically identical and completely homozygous at almost all loci, ensuring that they breed true to type.

Step 3: Final Answer:
Therefore, pure line breed refers to homozygosity, which is option (B).