Question 1

Which of the following best describes the difference between VNTRs and STRs in the context of DNA profiling?

Accepted Answer

VNTRs are variable number tandem repeats with longer repeat units (10-100 bp), while STRs are short tandem repeats with shorter repeat units (2-6 bp). Both are used for individual identification due to their high polymorphism.

Question 2

A forensic scientist runs a gel electrophoresis for 1 hour. What does it mean if a DNA fragment is closer to the (+) end of the gel compared to a fragment closer to the (-) end?

Accepted Answer

The band closest to the (+) end represents a smaller piece of DNA.

Question 3

Which type of transposable element (TE) can move by replicative transposition, and what is the consequence for genome size?

Accepted Answer

Autonomous TEs can move by replicative transposition, resulting in an increase in genome size because the original copy remains and a new copy is inserted elsewhere.

Question 4

During meiosis, what is normally separated in Meiosis I and Meiosis II?

Accepted Answer

Meiosis I separates homologous chromosomes; Meiosis II separates sister chromatids.

Question 5

A kitten with genotype $$C/c/c' ($$trisomy for chromosome D1) is born from parents with genotypes $$C/c$$ and $$c/c'. $$Which parent did the kitten inherit the C allele from?

Accepted Answer

Parent 1 ($$C/c)$$

Question 6

Non-disjunction in Meiosis I results in which of the following outcomes?

Accepted Answer

Homologous chromosomes fail to separate, leading to gametes with an extra or missing chromosome.

Question 7

Why does chromosome number matter for organismal survival, as illustrated by the Whoozit example?

Accepted Answer

Gene dosage imbalance from extra or missing chromosomes can disrupt development and gene expression, leading to inviability.

Question 8

Which of the following is a consequence of reciprocal translocation during meiosis?

Accepted Answer

Unbalanced gametes may be produced, leading to gene copy loss or gain and potential fertility issues.

Question 9

Which of the following best explains how STRs are used in forensic DNA profiling?

Accepted Answer

STRs are highly polymorphic, and the number of repeats at specific loci varies between individuals, allowing for unique genetic identification.

Question 10

A fly has the genotype $$y^+/cv^+/ct^+/sn^+/m^+$$ for five loci, where '+' indicates the dominant allele. What is the expected phenotype?

Accepted Answer

Grey body, crossveined wings, WT cut wings, WT bristles, normal sized wings

Question 11

Which of the following statements about SINEs and LINEs is correct?

Accepted Answer

SINEs are short interspersed nuclear elements that are non-autonomous and require LINEs for transposition.

Question 12

Which of the following is NOT a plausible child genotype given the STR gel results for parents with alleles 154/146 and 150/140?

Accepted Answer

150/140

Question 13

What is the main reason that highly polymorphic STR loci are preferred in forensic investigations?

Accepted Answer

They provide a high degree of discrimination between individuals due to many possible alleles at each locus.

Question 14

Which of the following is a real-world application of genetic genealogy in forensic science?

Accepted Answer

Identifying suspects in cold cases by comparing STR and SNP profiles to public genetic databases.

Question 15

Which of the following statements about the consequences of large-scale chromosomal mutations is correct?

Accepted Answer

They can lead to gene copy loss or gain, affecting gene dosage and potentially causing developmental disorders.

Question 16

Which of the following is true regarding the use of DNA kits with different numbers of loci for genetic genealogy?

Accepted Answer

Kits with more loci (e.g., 20 or 500,000 SNPs) provide greater certainty and can identify more distant relatives.

Question 17

Which of the following best describes the impact of translocation on gene expression?

Accepted Answer

Translocation can place a gene under the control of a different enhancer, altering its expression pattern.

Question 18

Which of the following gamete combinations would result in unbalanced gametes after segregation of translocated chromosomes during meiosis?

Accepted Answer

Gametes with both green chromosomes (trans green & normal green) or both yellow chromosomes (normal yellow & trans yellow).

Question 19

Which of the following is a potential reproductive outcome for couples with reciprocal balanced translocations?

Accepted Answer

Increased risk of infertility, recurrent miscarriages, and affected offspring due to unbalanced gametes.

Genetic Variation: Repetitive Sequences, Transposable Elements, and Chromosomal Rearrangements

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