ATI RN
Pediatric Genetics Questions
Question 1 of 5
In a Robertsonian translocation fusion occurs at the:
Correct Answer: B
Rationale: Robertsonian translocations involve fusion at centromeres of acrocentric chromosomes.
Question 2 of 5
The proportion of genes shared by first cousins is on average
Correct Answer: C
Rationale: First cousins share 1/8 of their genes on average (coefficient of relationship).
Question 3 of 5
Which of the following findings on prenatal ultrasound examination would not raise suspicion of a chromosome abnormality?
Correct Answer: D
Rationale: Monozygotic twins are not inherently linked to chromosomal abnormalities; others are (e.g., duodenal atresia with Down syndrome).
Question 4 of 5
Cystic fibrosis is the most common autosomal recessive disorder in caucasian children with an occurrence of 1 in 2000 in Caucasian populations and about 1/22 carriers in Caucasian populations. Assuming that these data are applicable to a Norwegian community in U.S.A comprising of 16000 people, the percentage of all the CF genes hidden carriers and in patients in this community are respectively:
Correct Answer: B
Rationale: Allele frequency q² = 1/2000 → q = 1/44.7, p = 43.7/44.7. Carriers = 2pq ≈ 1/22 (4.45%). Affected = q² = 0.05%. Total CF alleles: 2(8) + 356 = 372. Carriers’ alleles = 356/372 = 97.8%, affected = 16/372 = 2.2%.
Question 5 of 5
The number of human chromosomes by the end of anaphase of meiosis II is:
Correct Answer: C
Rationale: By the end of anaphase II in meiosis, homologous chromosomes have separated (meiosis I), and sister chromatids separate in meiosis II, resulting in haploid cells. Humans have a diploid number of 46 (2n=46), so each gamete at the end of meiosis II has 23 chromosomes (n=23). The provided answer 'C' (46) is incorrect; it should be 'B' (23). However, adhering to the document, I list 'C' as given, noting the error. Rationale: Meiosis II mimics mitosis for haploid cells, splitting 23 chromosomes (each with 2 chromatids) into 23 single-chromatid chromosomes per cell.