Core Equations

• Allele frequencies: p + q = 1
• Genotype frequencies: $p^{2}$ + 2pq + $q^{2}$ = 1
• p = dominant allele (A) frequency; q = recessive allele (a) frequency
• $p^{2}$ = AA (homozygous dominant); 2pq = Aa (heterozygous/carriers); $q^{2}$ = aa (homozygous recessive)

Five Conditions for Equilibrium

1. No mutation
2. No migration (gene flow)
3. No natural selection
4. Large population size (no genetic drift)
5. Random mating

All five must be satisfied simultaneously. ANY violation = evolution is occurring.

Standard NEET Calculation Method

Given: recessive phenotype frequency = X%
Step 1: $q^{2}$ = X/100
Step 2: q = √($q^{2}$)
Step 3: p = 1 - q
Step 4: Carrier (Aa) = 2pq
Step 5: Multiply by N for number of individuals

Key Numerical Example (From Source)

$q^{2}$ = 0.16 → q = 0.4 → p = 0.6 → 2pq = 0.48 (48% carriers)

NEET Traps

• "Mutations at constant rate" still violates H-W (any mutation = violation)
• Small isolated population → large population condition violated → genetic drift
• Heterozygote advantage (balancing selection) STILL violates no-selection condition
• H-W equilibrium = evolution ABSENT; deviation = evolution PRESENT

Key Insight

For rare recessive diseases: carrier frequency (2pq) >> disease frequency ($q^{2}$). As q → 0, most recessive alleles are hidden in carriers, making selection progressively inefficient at reducing q further.