Question

An \textit{Arabidopsis thaliana mutant plant developed defective flowers with altered floral organ identity and patterning. In this mutant, the four floral whorls contain Sepal-Sepal-Carpel-Carpel, from the periphery to the center of the flower. Based on the typical ABC model of floral organ patterning, which among the following are mutated in this plant?}

• A. Class A gene(s)
• B. Class B gene(s)
• C. Class C gene(s)
• D. Double mutant for Class A and Class C genes

Hint:

In the ABC model, Class B genes are responsible for determining the identity of petals and stamens. Mutation in these genes results in the loss of proper petal and stamen formation.

Answer 1

The Correct Option is B

Step 1: Understand the ABC model.
The ABC model of flower development explains the identity of floral organs in a plant. Class A genes determine the identity of sepals and petals, Class B genes determine the identity of petals and stamens, and Class C genes determine the identity of stamens and carpels.
Step 2: Analyze the mutation.
In the given mutant plant, the floral whorls contain Sepal-Sepal-Carpel-Carpel, which means the patterning of petals and stamens is disrupted. Since petals and stamens are affected, it indicates a mutation in Class B genes, as they are responsible for the proper formation of these organs.

Step 3: Conclusion.
The correct answer is (B) Class B gene(s), as they are mutated in this plant to cause the observed floral patterning defect.