The risk for miscarriage associated with amniocentesis is approximately

Correct Answer: C

Rationale: Amniocentesis carries a miscarriage risk of ~0.5-1% (1 in 100-200).

Correct Answer: C

Rationale: Deletion (if not in multiples of 3) shifts the reading frame; substitutions (A-E) do not.

Correct Answer: C

Rationale: In G2 phase, after DNA replication (S phase), each of the 46 chromosomes consists of 2 sister chromatids (double-stranded DNA molecules). Thus, 92 double-stranded molecules exist. Answer 'C' (92) is correct. Rationale: Each chromosome’s chromatids are identical double helices, totaling 92 in a diploid human cell (2n=46).

Correct Answer: A

Rationale: Cytogenetics (A) studies chromosomes and cell division. Rationale: Cytology is broader (cell biology), and pedigree is inheritance charting. Cytogenetics focuses on karyotypes and meiosis/mitosis.

Correct Answer: C

Rationale: 45, XY, t(14,21) (C) is a balanced Robertsonian translocation, phenotypically normal. Rationale: 46, 0Y is inviable (no X), trisomy 14 is lethal, but t(14;21) carriers have normal gene content despite 45 chromosomes.