Inheritance of One and Two Genes — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Inheritance of One and Two Genes.

Complex Dihybrid Probability Problems

high

NEET often tests the application of Mendelian principles in slightly more complex scenarios. Instead of just asking for the 9:3:3:1 phenotypic ratio, questions might ask for the probability of a specific genotype (e.g., RrYY) or a specific phenotypic combination (e.g., round green) from a dihybrid cross. This requires students to use the probability method effectively, breaking down the dihybrid cross into two independent monohybrid crosses and multiplying the probabilities. This tests a deeper understanding than simple ratio recall and is a good discriminator.

Deducing Parental Genotypes from Offspring Ratios

medium

A common and slightly more challenging question type involves providing the phenotypic or genotypic ratios of the offspring and asking students to determine the genotypes of the parents. This requires working backward from the results, often involving a trial-and-error approach or a strong conceptual grasp of how different parental crosses yield specific ratios. This tests analytical skills and the ability to apply Mendelian laws in reverse, which is a higher-order thinking skill.

Conceptual Questions on Exceptions/Modifications (Briefly)

low

While 'Inheritance of One and Two Genes' primarily focuses on classical Mendelian inheritance, NEET sometimes includes questions that subtly hint at or briefly touch upon modifications like incomplete dominance or codominance, even if those are covered in subsequent topics. For example, a question might describe a cross where the F1 generation shows an intermediate phenotype, and then ask which Mendelian principle is *not* strictly followed. This tests the student's ability to recognize deviations from standard Mendelian ratios and understand the limitations of the basic laws, setting the stage for more advanced genetics.

Test Cross for Multiple Unknowns

medium

Beyond a simple monohybrid test cross, questions could involve a dihybrid test cross or a scenario where multiple individuals with dominant phenotypes need their genotypes determined. For example, 'You have three tall pea plants. How would you determine their genotypes using a single type of cross, and what results would you expect for each?' This combines the concept of a test cross with the need to differentiate between multiple possibilities, requiring a comprehensive understanding of the technique.