Core Equations

Allele Frequency Equation:

p + q = 1

where: p = frequency of dominant allele (A), q = frequency of recessive allele (a)

Genotype Frequency Equation:

$p^{2}$ + 2pq + $q^{2}$ = 1

where:

• $p^{2}$ = frequency of AA (homozygous dominant)
• 2pq = frequency of Aa (heterozygous carriers)
• $q^{2}$ = frequency of aa (homozygous recessive)

Standard NEET Problem-Solving Algorithm

Step 1: Identify $q^{2}$ from the recessive phenotype frequency
         → Recessive phenotype (aa) = $q^{2}$

Step 2: Calculate q
         → q = √($q^{2}$)

Step 3: Calculate p
         → p = 1 - q

Step 4: Calculate the required genotype frequency
         → Carrier (Aa) = 2pq
         → Homozygous dominant (AA) = $p^{2}$

Step 5: Multiply by population size if a NUMBER is required
         → Number of carriers = 2pq × N

Worked Example (from source)

Problem: 16% of population shows recessive phenotype. Find dominant allele frequency and carrier frequency.

$q^{2}$ = 0.16
q = √0.16 = 0.4
p = 1 - 0.4 = 0.6 ← Dominant allele frequency = 0.6 (ANSWER)
Carrier frequency = 2pq = 2 × 0.6 × 0.4 = 0.48 = 48%

Five Conditions for H-W Equilibrium

Key Insight

H-W equilibrium is a MATHEMATICAL BASELINE — the null hypothesis for evolution. Any deviation from H-W means evolution is occurring.