If a GAMETE chromosomes are 16, what is the number of chromatids before anaphase 1?

Correct Answer: D

Rationale: If a gamete has 16 chromosomes (n=16), the diploid cell (2n=32) before meiosis I has 32 chromosomes, each with 2 chromatids post-S phase, totaling 64 chromatids. 'D' is correct. Rationale: Before anaphase I, homologous pairs align; each chromosome has duplicated, so 32 x 2 = 64 chromatids.

Correct Answer: B

Rationale: Duplication (B) adds genetic material. Rationale: Deletion removes, translocations rearrange (no net gain), while duplication increases gene copies, potentially causing phenotypes like Charcot-Marie-Tooth.

Correct Answer: D

Rationale: 0 maternal, 2 paternal sets form a complete mole. Rationale: Sperm (23) fertilizes an empty egg and duplicates (46, XX or YY), all paternal, no fetus.

Correct Answer: B

Rationale: MI: homologous chromosomes; MII: sister chromatids (B). Rationale: MI separates homologs, MII splits chromatids, causing aneuploidy if nondisjunction occurs.

Correct Answer: C

Rationale: Amniotic fluid (C) is used in amniocentesis for fetal karyotyping. Rationale: It contains fetal cells (amniocytes) for chromosome analysis; lymphocytes and bone marrow are postnatal, cheek swabs aren’t fetal, and skin biopsy is rare prenatally.