Practice question

Hybrid dysgenesis manifests when P-strain males bearing 30-50 euchromatic P elements are crossed to M-strain females lacking P elements and corresponding piRNA mediated repression. Maternal piRNAs normally deposited in oocyte cytoplasm silence transposons; M females lack these, so progeny germline experiences derepressed P transposase activity causing rampant cut-and-paste mobilization generating double-strand breaks, mutations, and sterility known as gonadal dysgenesis. Reciprocal cross with P female provides piRNAs suppressing transposition, yielding fertile progeny demonstrating cytoplasmic inheritance of transposon control via small RNAs. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.