Which of the following genetic changes is associated with a female whose karyotype is 46, XY?

Correct Answer: A

Rationale: 46, XY female indicates SRY mutation (A). Rationale: SRY on Y determines maleness; mutations prevent testis development, resulting in female phenotype despite XY karyotype. Monosomy X is 45, X; Triple X is 47, XXX.

Correct Answer: C

Rationale: Paternal nondisjunction (C) causes 47, XYY. Rationale: Meiosis II nondisjunction in father produces YY sperm (24, YY), fertilizing X egg (23, X), yielding 47, XYY. Chimerism or UPD don’t fit; maternal nondisjunction gives XXY.

Correct Answer: B

Rationale: Eye lens cells (epithelial) are diploid (2n=46), like most somatic cells. 'B' is correct. Rationale: Haploid (n=23) is for gametes, triploid (3n) and tetraploid (4n) are abnormal and rare in humans. Lens cells divide mitotically, maintaining diploidy.

Correct Answer: A

Rationale: Beta satellite DNA is on the p-arm of acrocentric chromosomes (e.g., 13, 14, 15, 21, 22). 'A' is correct. Rationale: These repetitive sequences are near nucleolar organizer regions (NORs) on short arms, distinct from centromeric alpha satellites.

Correct Answer: D

Rationale: 69, YYY (D) cannot occur in triploidy. Rationale: Triploidy (3n=69) results from dispermy or diploid gametes (e.g., XXY, XXX), but YYY requires three Y-bearing sperms, biologically implausible in humans.