Govt Exams
Genomic imprinting involves parent-specific gene silencing. If only the paternal mutation causes disease, it indicates the maternal allele is normally silenced (imprinted), making the paternal allele the only functional copy.
Epigenetic changes (DNA methylation, histone modifications) and differential environmental exposure can cause phenotypic differences in genetically identical individuals.
Aa × Aa normally produces 1 AA : 2 Aa : 1 aa. If AA is lethal, only Aa and aa survive in a 2:1 ratio.
These structures share similar bone arrangements despite different functions, indicating descent from a common ancestor with modification—evidence for divergent evolution.
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.
Using Hardy-Weinberg equation: frequency of Aa = 2pq = 2(0.7)(0.3) = 0.42. This remains constant across generations in equilibrium.