Practice question

Repeated self-fertilization progressively eliminates heterozygosity because each heterozygous locus segregates 1 AA:2 Aa:1 aa, only half progeny retain heterozygosity. Mathematically heterozygosity after t generations Ht equals H0 multiplied by one-half raised to power t, so after seven generations approximately 0.8 percent remains. Continuous inbreeding drives allele fixation toward homozygous states, exposing recessive homozygotes for selection. In breeding this rapid homozygosization underlies development of pure lines, recombinant inbred lines for QTL mapping and near-isogenic lines via repeated backcross selfing. While genetic uniformity achieved, fitness may decline if deleterious alleles uncovered, necessitating concurrent selection against weak segregants to identify vigorous homozygotes retaining yield potential and adaptation. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs. Additional insights from genomic studies reveal QTL clusters, epigenetic modifications and protein interactions that influence trait expression under varied agro-climatic conditions and management.