Skip to main content
Super TutorResources
Chapter 8 of 32
SyllabusNotesTopicsQuestionsPlanFormulas
Revision Notes

Principles of Inheritance and variation — Revision Notes

CUET (UG) · Biology

Quick revision notes for Principles of Inheritance and variation — key concepts, formulas, and definitions for CUET (UG) Biology preparation.

Interactive on Super Tutor

Studying Principles of Inheritance and variation? Get the full chapter — free.

Practice questions, revision notes, formula sheet and AI doubt-solver — built for CUET (UG) Biology.

Try Super Tutor — Free
A comparison chart illustrating Mendel's seven pairs of contrasting traits in pea plants, showing both dominant and recessive phenotypes for each trait.
Super Tutor

Learn better with visuals Super Tutor has hundreds of illustrations like this across every chapter — all free to try.

Get started

Revision Notes — Principles of Inheritance and variation

Key concepts, formulas, and definitions from Principles of Inheritance and variation for CUET (UG) Biology preparation.

Key Topics to Revise

1

4.1 Mendel's Laws of Inheritance

  • Gregor Mendel (1822-1884) is called the 'Father of Genetics' who worked on garden pea (Pisum sativum) from 1856-1863
  • Mendel chose pea plants because: annual plant with short life cycle, many contrasting traits, natural self-pollination, successful artificial cross-pollination possible, easy cultivation, produces lar
  • True-breeding lines: Plants showing stable trait inheritance for several generations through continuous self-pollination
2

4.2 Law of Dominance and Law of Segregation

  • Law of Dominance: Characters are controlled by discrete units (factors/genes) that occur in pairs; in dissimilar pairs, one dominates over the other
  • Law of Segregation (Law of Purity of Gametes): Allele pairs separate during gamete formation so each gamete receives only one allele of each gene
  • Incomplete Dominance: Neither allele is completely dominant; F₁ shows intermediate phenotype (e.g., red × white = pink in snapdragon)
3

4.3 Inheritance of Two Genes - Dihybrid Cross

  • Law of Independent Assortment: When two pairs of contrasting traits are combined in a hybrid, segregation of one pair is independent of the other pair
  • Dihybrid cross involves two pairs of contrasting traits studied simultaneously
  • F₁ dihybrid produces four types of gametes in equal proportions (1:1:1:1)
4

4.4 Polygenic Inheritance and 4.5 Pleiotropy

  • Polygenic Inheritance: Multiple genes control a single trait; each gene contributes additively to the phenotype
  • Examples include human skin color (controlled by 3 gene pairs A, B, C), height, and wheat kernel color
  • Shows continuous variation rather than discrete categories

Get complete revision notes with diagrams and examples — continue in Super Tutor

Key Concepts

Three fundamental laws discovered by GregorProposed by Sutton and BoveriIncomplete dominance occurs when neither alleleSex determination involves different chromosome systemsGenes located on the same chromosome

Frequently Asked Questions

What topics are covered in Principles of Inheritance and variation for CUET (UG)?
Principles of Inheritance and variation is an important chapter in CUET (UG) Biology. It covers key concepts and formulas that are frequently tested in the exam. Key topics include: 4.1 Mendel's Laws of Inheritance, 4.2 Law of Dominance and Law of Segregation, 4.3 Inheritance of Two Genes - Dihybrid Cross, 4.4 Polygenic Inheritance and 4.5 Pleiotropy.
How important is Principles of Inheritance and variation for CUET (UG)?
Principles of Inheritance and variation is a frequently tested chapter in CUET (UG) Biology. Questions from this chapter appear regularly in previous year papers. There are 117 practice questions available for this chapter.
How to prepare Principles of Inheritance and variation for CUET (UG)?
Start by understanding the core concepts, then solve practice questions. Focus on formulas and their applications. Use revision notes for quick review before the exam.

More resources for Principles of Inheritance and variation

All 32 chapters — CUET (UG) Biology Revision Notes

For CUET (UG) aspirants

Get the full Principles of Inheritance and variation chapter — for free.

Practice questions, revision notes, formula sheet and AI doubt-solver for CUET (UG) Biology.

Try Super Tutor Free
Try the full chapter — Free