Question

p2 + 2pq + q2 = 1. Explain this algebraic equation on the basis of Hardy Weinberg's principle. 

CBSE Class XII Biology Question Paper 2017

Answer 1

This is a bionomial expansion of (p+q)2. The equation p2 + 2pq + q2 = 1,mathematically represents the Hardy-Weinberg’s principle. It is used to calculate the genetic variation of a population at equilibrium. Principle It states that allele frequencies in a population are stable and remain constant from generation to generation. In this equation,



p – frequency of allele A

q – frequency of allele a

p 2 – frequency of AA (homozygous) individuals in a population

q 2 – frequency of aa (homozygous) individuals

2pq – frequency of Aa (heterozygous) individuals

Also, the sum total of all the allelic frequencies is equal to 1. If the p and q allele frequencies are known, then the frequencies of the three genotypes can be calculated using the Hardy-Weinberg equation.

This equation can be used to measure the differences in frequencies of observed genotype measured from the frequencies predicated by the equation. The disturbance in genetic equilibrium results in evolution, thus the presence of any difference indicates the exent of evolutionary change.

Answer 2

Hardy Weinberg's Principle

Explanation:

• Hardy Weinberg's principle which is utilized to calculate the genetic variation of a population at equilibrium
• This principle expresses that "Allele frequencies in a population are stable and stay consistent from generation to generation"
• It is a bionomial development of (p+q)2. The condition p2 + 2pq + q2 = 1  

p – frequency of allele A  

q – frequency of allele a  

p 2 – frequency of AA (homozygous) individuals in a population

q 2 – frequency of aa (homozygous) individuals  

2pq – frequency of Aa (heterozygous) individuals  

• The total of all the allelic frequencies is equivalent to 1. if the p and q allele frequencies are known, at that point the frequencies of the three genotypes can be determined utilizing the Hardy-Weinberg equation