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CBSE · Class 12 · Biology

Biology Formula Sheet

4 formulas across 2 chapters — with variables explained and exam tips where needed.

Ch 5Molecular Basis of Inheritance(3 formulas)

Chargaff's Rule

A = T | G = C | A+G = T+C (Purines = Pyrimidines)

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Most important equation in genetics — appears every year

DNA base percentage

If A% is given: T = A%, G = C = (100 − 2A)/2 %

Number of H-bonds in DNA

H-bonds = 2×(A=T pairs) + 3×(G≡C pairs)

Ch 6Evolution(1 formulas)

Hardy-Weinberg Principle

p² + 2pq + q² = 1 and p + q = 1

p = frequency of dominant allele, q = frequency of recessive allele

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CBSE Class 12 Biology Formula Sheet 2025-26 — All Chapters | ClearSteps