Class 12 · Principles of Inheritance and Variation

Mendel's Laws of Inheritance — NEET Biology

📚 Practice Concept
📖 NCERT Source

Genetics is a branch of biology which deals with principles of inheritance and its practices. Progeny resembling the parents in morphological and physiological features has attracted the attention of many biologists. Mendel was the first to study this phenomenon systematically. While studying the pattern of inheritance in pea plants of contrasting characters, Mendel proposed the principles of inheritance, which are today referred to as 'Mendel's Laws of Inheritance'. He proposed that the 'factors' (later named as genes) regulating the characters are found in pairs known as alleles. He observed that the expression of the characters in the offspring follow a definite pattern in different-first generations (F₁), second (F₂) and so on. Some characters are dominant over others. The dominant characters are expressed when factors are in heterozygous condition (Law of Dominance). The recessive characters are only expressed in homozygous conditions. The characters never blend in heterozygous condition. A recessive character that was not expressed in heterozygous condition may be expressed again when it becomes homozygous. Hence, characters segregate while formation of gametes (Law of Segregation).

NCERT Biology · Class 12 · Chapter 4 · Paragraph 97
Practice This Concept
QuestionPractice Question

Which of the following statements regarding Mendel's experiments and laws of inheritance are correct? S1: Mendel studied seven pairs of contrasting traits in pea plants, including pod shape (inflated/constricted) and seed colour (yellow/green). S2: Leaf colour (red/green) and seed texture (rough/smooth) were among the specific traits investigated by Mendel in pea plants. S3: In a monohybrid cross between a true-breeding tall plant and a true-breeding dwarf plant, all F1 progeny express the dwarf phenotype, demonstrating the recessive nature of tallness. S4: The Law of Segregation states that during gamete formation, the alleles of a pair segregate from each other, ensuring each gamete receives only one allele with equal proportion. S5: A test cross involves crossing an organism showing a dominant phenotype (whose genotype is to be determined) with a heterozygous recessive parent. S6: Mendel's significant contribution included the application of statistical analysis and mathematical logic to biological problems, which was novel for his time.

Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.

88/90
of the NEET 2026 Biology paper matched from the MedicNEET question bank

MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.

88 of 90 NEET 2026 Biology questions traced to MedicNEET10,000+ Biology questionsHindi + English
Free to start · Hindi + English · 10,000+ questions · NEET 2026 pattern
Related Concepts from Principles of Inheritance and Variation
📘Practice all 49 NEET PYQs from Principles of Inheritance and Variation🔍See full Principles of Inheritance and Variation PYQ Analysis