Question

Pureline theory was given by Johannsen on working with:

• A. Pea
• B. 'Princess' variety of French bean
• C. Vicia Faba
• D. Norin 10

Hint:

Johannsen introduced the important genetic terms “Genotype” and “Phenotype” through his pureline experiments.

Answer 1

The Correct Option is B

Concept: Pureline theory states that a pureline consists of the progeny of a single homozygous self-pollinated plant. Variations observed within a pureline are environmental and not genetic.

Step 1: Identify the crop used by Johannsen.
Wilhelm Johannsen conducted experiments using the “Princess” variety of French bean (Phaseolus vulgaris) to study inheritance and selection.

Step 2: Understand the conclusion of the experiment.
Johannsen observed that selecting large or small seeds within the same pureline did not permanently alter the average seed size in future generations. This demonstrated that selection within a pureline is ineffective because all individuals possess the same genotype. Hence, the pureline theory was proposed based on work with the “Princess” variety of French bean.