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Formula Sheet

Principles of Inheritance and Variation — Formula Sheet

ICSE · Class 12 · Biology

5 formulas from Principles of Inheritance and Variation (ICSE Class 12 Biology) on one page, grouped by topic. Part of the ICSE Class 12 Biology syllabus.

130 questions50 flashcards5 formulas & key relations5 concepts

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A detailed diagram illustrating the process of crossing over, where genetic material is exchanged between non-sister chromatids of homologous chromosomes during Pachytene of Prophase I.
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5 Entries · 1 Section

Formulas and Key Relations

3. Mendel’s Laws and Ratios

Monohybrid F2 Phenotypic Ratio: 3 : 1 [dominant : recessive phenotype]

Monohybrid F2 Genotypic Ratio: 1 : 2 : 1 [homozygous dominant : heterozygous : homozygous recessive]

Dihybrid F2 Phenotypic Ratio: 9 : 3 : 3 : 1 [round yellow : round green : wrinkled yellow : wrinkled green]

Dihybrid F2 Genotypic Ratio: 1 : 2 : 1 : 2 : 4 : 2 : 1 : 1 : 1 : 1 [RRYY : RRYy : rrYY : RrYY : RrYy : rrYy : Rryy : Rryy : RRyy : rryy]

Trihybrid Ratio: 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1 [phenotypic classes for three-gene cross]

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Frequently Asked Questions

What are the important topics in Principles of Inheritance and Variation for ICSE Class 12 Biology?
Key topics in Principles of Inheritance and Variation include Heredity, Variation, and Mendel’s Work, Mendel’s Laws and Basic Crosses, Deviations from Mendelism: Incomplete Dominance, Co-dominance, Pleiotropy, and Multiple Alleles, Chromosomal Theory, Linkage, and Crossing Over. Study these first, then practise questions on each for the ICSE Class 12 board exam.
How many formulas are in Principles of Inheritance and Variation?
This sheet lists 5 formulas from Principles of Inheritance and Variation, grouped by topic. Learn what each symbol stands for so you can apply the formula, not just recall it.
How should I revise Principles of Inheritance and Variation for the ICSE Class 12 board exam?
Learn the core ideas first, then work through the 130 practice questions on Principles of Inheritance and Variation. Revise 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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All ICSE Class 12 Biology Formula Sheet

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