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Principles of Inheritance and Variation

CBSE · Class 12 · Biology

Complete topic list for Principles of Inheritance and Variation in CBSE Class 12 Biology. Key concepts, sub-topics, and what to focus on for board exams.

39 questions80 flashcards5 concepts

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A comparison chart illustrating Mendel's seven pairs of contrasting traits in pea plants, showing both dominant and recessive phenotypes for each trait.
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4 Topics · CBSE Class 12 Biology

Topics in Principles of Inheritance and Variation

1

1. Mendel’s Work and Basic Terms

  • Genetics deals with inheritance and variation.
  • Inheritance is the process by which characters are passed on from parent to progeny; it is the basis of heredity.
  • Variation is the degree by which progeny differ from their parents.
2

2. Inheritance of One Gene: Monohybrid Cross

  • Mendel crossed tall and dwarf pea plants to study inheritance of one gene.
  • In the F1 generation, all plants were tall and none were dwarf.
  • In the F2 generation, the phenotypic ratio was 3 tall : 1 dwarf.
3

3. Incomplete Dominance and Co-dominance

  • Incomplete dominance occurs when the F1 phenotype is intermediate between the two parents.
  • In snapdragon, red-flowered RR crossed with white-flowered rr produces pink F1 plants of genotype Rr.
  • The F2 ratio in this case is 1 red : 2 pink : 1 white.
4

4. Dihybrid Cross and Independent Assortment

  • Mendel crossed plants differing in two characters, such as seed shape and seed colour.
  • Round shape is dominant over wrinkled and yellow colour is dominant over green.
  • The F1 genotype in the standard dihybrid cross is RrYy.

Key Concepts

Central concept: Genetics: the study of inheritance and variation in living organisms

Mendel's laws of inheritanceOne gene inheritanceVariation in dominance patternsTwo gene inheritanceChromosomal theory of inheritanceLinkage and recombinationSex determinationMutation

Frequently Asked Questions

What are the important topics in Principles of Inheritance and Variation for CBSE Class 12 Biology?
Principles of Inheritance and Variation covers several key topics that are frequently asked in CBSE Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Principles of Inheritance and Variation — CBSE Class 12 Biology?
Understand the core concepts first, then work through the 39 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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