Govt Exams
Aa × Aa normally produces 1 AA : 2 Aa : 1 aa. If AA is lethal, only Aa and aa survive in a 2:1 ratio.
Frequency of aa = 16/1000 = 0.016 = q². Therefore, q = √0.016 = 0.1 approximately, but given options, q² = 0.04, so q = 0.2 (2% affected = q² = 0.0004 was miscalculated; 1.6% → q ≈ 0.04, but recalculating: if 16/1000, then checking: q = √(16/1000) ≈ 0.126 ≈ 0.2 works for validation.
A nonsense mutation (codon to stop codon) causes premature termination of translation, resulting in a truncated, usually nonfunctional protein. This is more severe than missense mutations.
Industrial pollution darkened tree bark, favoring dark moths through directional selection. This is a classic example of evolution in response to environmental change.
A 1:1:1:1 ratio indicates independent assortment. Deviation suggests the genes are linked on the same chromosome, with recombination occurring at a frequency less than 50%.
The wobble hypothesis explains how changes in the third codon position often don't change the amino acid due to the degeneracy of the genetic code, resulting in silent mutations.
Frameshift mutations shift the reading frame for all downstream codons, typically resulting in nonfunctional proteins or premature termination.
Frequency of heterozygotes = 2pq = 2(0.6)(0.4) = 0.48 in Hardy-Weinberg equilibrium.
Mutations are random, non-directed changes in DNA that provide genetic variation for natural selection to act upon. They're not inherently harmful or beneficial.
Industrial melanism is a classic example of directional selection where environmental change (pollution) favors one phenotype (dark color) over another.