Previous Year Papers NEET Biology Class 12 – Principles of Inheritance and Variation

Principles of Inheritance and Variation is a crucial chapter of NEET Biology Class 12 that explains the mechanisms of heredity, Mendelian laws, patterns of inheritance, and causes of genetic variation. Mastery of this chapter is essential for answering both theoretical and problem-based NEET questions.

NEET previous year papers frequently include questions on Mendelian experiments, Punnett squares, inheritance patterns, mutations, and chromosomal disorders. Practicing PYQs helps students strengthen understanding of heredity and variation. Studentbro.in provides exam-focused material for effective preparation.

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Mendelian Genetics – NEET PYQ Focus

Gregor Mendel’s experiments with pea plants established the foundation of genetics. Key principles include:

• Law of Segregation – Two alleles segregate during gamete formation.

• Law of Independent Assortment – Alleles of different traits assort independently.

NEET questions often test monohybrid and dihybrid crosses, genotype, phenotype ratios, and Mendelian principles.

Monohybrid and Dihybrid Crosses – Important NEET Concepts

• Monohybrid Cross – Involves a single trait; results in a 3:1 phenotypic ratio in F2.

• Dihybrid Cross – Involves two traits; results in a 9:3:3:1 phenotypic ratio in F2.

Previous year papers frequently ask to solve problems using Punnett squares, identify parental and filial generations, and calculate genotypic and phenotypic ratios.

Incomplete Dominance and Co-Dominance – Key Concepts

• Incomplete Dominance – Heterozygote shows intermediate phenotype (e.g., snapdragon flower color).

• Co-Dominance – Both alleles expressed equally (e.g., AB blood group).

NEET PYQs may ask for examples and pattern analysis.

Multiple Alleles and Blood Groups

• ABO blood group system is controlled by multiple alleles (IA, IB, i).

• Rh factor (positive/negative) also plays a role in inheritance.

NEET questions often involve determining blood type from parental genotypes.

Sex-Linked Inheritance – NEET PYQ Focus

Sex-linked traits are carried on sex chromosomes (X or Y):

• X-linked recessive – Hemophilia, color blindness.

• X-linked dominant – Rett syndrome.

Previous year papers frequently ask to predict phenotypes and genotypes in offspring.

Mutation – Source of Variation

Mutations are changes in DNA sequence that create genetic variation. Types include:

• Point Mutation – Single base change.

• Chromosomal Mutation – Deletion, duplication, inversion, translocation.

NEET PYQs may test causes, types, and examples of mutations and their significance in evolution.

Chromosomal Disorders in Humans

Common chromosomal disorders include:

• Down Syndrome – Trisomy 21.

• Turner Syndrome – Monosomy X.

• Klinefelter Syndrome – XXY males.

NEET questions often involve karyotype interpretation, symptoms, and inheritance patterns.

Importance of Previous Year Papers for NEET Biology

Practicing previous year papers helps students identify frequently asked topics, reinforce conceptual understanding, and improve speed. PYQs for Principles of Inheritance and Variation focus on Mendelian genetics, inheritance patterns, mutations, and chromosomal disorders.

Conclusion

Previous Year Papers of NEET Biology Class 12 Principles of Inheritance and Variation are essential for mastering genetics and heredity. This chapter requires clear understanding of Mendelian laws, monohybrid and dihybrid crosses, sex-linked traits, mutations, and chromosomal disorders.

Regular practice of PYQs helps students enhance conceptual clarity, problem-solving skills, and confidence in NEET. Studentbro.in provides structured, reliable, and exam-focused content to help NEET aspirants succeed.