Which of the following diagnostic techniques is of no value for the diagnosis of neural tube defects?

Correct Answer: B

Rationale: CVS tests chromosomes, not neural tube defects (NTDs); others detect NTDs via AFP or imaging.

Correct Answer: B

Rationale: The number of possible chromosome combinations in meiosis is 2^n, where n is the haploid number. If diploid is 10 (2n=10), then haploid is 5 (n=5). Thus, 2^5 = 32 combinations. Answer 'B' (32) is correct. Rationale: Each chromosome segregates independently (Mendel’s Law of Independent Assortment), so with 5 chromosome pairs, there are 2 choices (maternal or paternal) per pair, yielding 32 unique gametes.

Correct Answer: C

Rationale: Telomeres don’t code for genes (C is false). Rationale: Telomeres are TTAGGG repeats (A), shorten with replication (B), and protect chromosome ends (D). They’re non-coding, and telomerase activity is high in cancer (E), making 'C' the exception.

Correct Answer: C

Rationale: Down syndrome is 47, XX, +21, not +18 (C is mismatched). Rationale: Patau is +13 (A), Edwards is +18 (B), but Down is +21, making 'C' incorrect.

Correct Answer: B

Rationale: Triploidy is incompatible with adult life (B). Rationale: 69, XXY (not listed) or similar triploids (3n) occur but are lethal or result in miscarriage. 92 (4n) or 23 (n) don’t fit triploidy (3n=69). Adults don’t survive triploidy.