Class 12 · Evolution

Hardy-Weinberg Equilibrium & Gene Pool — NEET Biology

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📖 NCERT Source

This principle says that allele frequencies in a population are stable and is constant from generation to generation. The gene pool (total genes and their alleles in a population) remains a constant. This is called genetic equilibrium. Sum total of all the allelic frequencies is 1. Individual

🖼️Related NCERT figure: Diagrammatic representation showing three bell curves illustrating different types of natural selection. The graphs show number of individuals with phenotype on y-axis. (a) shows stabilizing selection with peak getting higher and narrower, (b) shows directional selection with peak shifting in one direction, and (c) shows disruptive selection with two peaks forming. (Figure 6.8 Diagrammatic representation of the operation of natural selection on different traits : (a) Stabilising (b) Directional and (c) Disruptive)
NCERT Biology · Class 12 · Chapter 6 · Paragraph 34
How NTA Uses This Concept

NTA tests whether students understand that allele frequencies remain constant across generations in a stable population (genetic equilibrium), meaning the gene pool doesn't change. Students often confuse this with population size or mistakenly think allele frequencies change every generation, forgetting that equilibrium conditions prevent evolution. The key trap is assuming any population maintains equilibrium—students must remember that equilibrium requires no mutation, no selection, random mating, and no gene flow. To score correctly: recall that the sum of all allelic frequencies equals 1, and this constancy is why Hardy-Weinberg serves as a null hypothesis for detecting evolution in real populations.

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QuestionNEET 2024

Which one of the following factors will not affect the Hardy-Weinberg equilibrium? (NEET 2024)

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