Why does p+q=1 The difference between the allele frequencies is 1or 100% The recessive allele is usually less frequent than the dominant allele. There is one gene for every allele which adds up to 1 The percent chance of having either allele adds up to 1 or 100%

The correct answer is: The percent chance of having either allele adds up to 1 or $100\%$.<br /><br />In population genetics, the Hardy-Weinberg principle states that allele frequencies in a population remain constant from generation to generation in the absence of other evolutionary influences. In this principle, the sum of the allele frequencies for a particular gene is always equal to 1 (or 100%).<br /><br />The equation $p+q=1$ represents the sum of the allele frequencies for a gene, where $p$ is the frequency of the dominant allele and $q$ is the frequency of the recessive allele. This equation is based on the assumption that there is no mutation, migration, or selection acting on the gene, and that the population is infinitely large.<br /><br />The other options provided are not accurate explanations for why $p+q=1$. The difference between the allele frequencies being 1 or 100% does not explain the equation. The recessive allele being less frequent than the dominant allele is not a requirement for the equation. Lastly, the statement that there is one gene for every allele which adds up to 1 is not a valid explanation for the equation.