Unit 4: Advances in Molecular Biology & Genetics - Practice Quiz

1 What is the primary molecule that stores genetic information in most living organisms?

2 The process of copying DNA into a complementary RNA molecule is called:

3 Which technique is widely used to amplify specific DNA sequences in the laboratory?

4 In the DNA double helix, adenine (A) pairs with which base?

5 The CRISPR-Cas9 system is primarily used for:

6 Which sugar is found in RNA but not in DNA?

7 The complete set of genes in an organism is known as its:

8 Translation is the process by which:

9 Which enzyme is responsible for synthesizing new DNA strands during replication?

10 Gel electrophoresis separates DNA fragments primarily based on their:

11 A change in the DNA sequence of a gene is called a:

12 Which base found in RNA replaces thymine of DNA?

13 The 'central dogma' of molecular biology describes the flow of information from:

14 Restriction enzymes are used in molecular biology to:

15 A gene is best defined as a:

16 Which technology allows scientists to insert a gene from one organism into another?

17 The set of three nucleotides that codes for a specific amino acid is called a:

18 Sequencing of the entire human genome was completed under which major project?

19 Which structure carries genes and is composed of DNA and protein?

20 The study of how gene expression changes without altering the DNA sequence is called:

21 A researcher wants to selectively amplify a specific 500 bp region from genomic DNA before sequencing. Which technique is most appropriate as the first step?

22 In CRISPR-Cas9 genome editing, the guide RNA primarily functions to:

23 A gene of interest shows high mRNA levels but very low protein output in a cell. Which mechanism most likely explains this observation?

24 During a study, a scientist observes that a restriction enzyme cuts a plasmid at a single site, linearizing it. What can be inferred about the recognition sequence?

25 In quantitative real-time PCR (qPCR), a lower cycle threshold () value indicates:

26 A transgenic plant is engineered to express a bacterial gene. For the gene to be expressed correctly, the construct must include a:

27 RNA interference (RNAi) is being used to knock down a target gene. The functional molecule that guides degradation of the target mRNA is:

28 A DNA sample analyzed by gel electrophoresis migrates faster than a known 1 kb marker. This suggests the sample fragment is:

29 A point mutation changes a codon from UAC to UAA. What is the most likely consequence for the protein?

30 In a Western blot experiment, the antibodies are used to detect:

31 A researcher observes that a gene is silenced without any change in its DNA sequence, and silencing is heritable across cell divisions. This is best explained by:

32 Next-generation sequencing (NGS) offers a major advantage over Sanger sequencing primarily because it enables:

33 A cloning vector must contain a selectable marker so that researchers can:

34 In a diploid organism, an autosomal recessive disease allele has frequency . Under Hardy-Weinberg equilibrium, the expected frequency of affected individuals is:

35 A reverse transcriptase enzyme is essential in cDNA synthesis because it:

36 A microarray experiment shows a set of genes strongly upregulated after drug treatment. The most direct interpretation is that the drug increased:

37 Two genes located close together on the same chromosome tend to be inherited together. This phenomenon is called:

38 A researcher uses a GFP reporter fused to a promoter to study gene expression. Fluorescence intensity in the cells serves as a measure of:

39 During DNA replication, the leading and lagging strands differ because DNA polymerase can only synthesize DNA in the:

40 A knockout mouse is generated to study a gene's function. The expected outcome of a successful knockout is:

41 In a CRISPR-Cas9 experiment, a researcher observes high off-target cleavage. Switching to a high-fidelity Cas9 variant (e.g., HiFi-Cas9) reduces off-targets but also lowers on-target efficiency. Which mechanistic explanation best accounts for this trade-off?

42 A gene with two alleles shows allele frequencies and . Under Hardy–Weinberg equilibrium, a researcher finds the observed heterozygote frequency is instead of the expected value. What is the fixation index ?

43 During RNA-seq analysis, a lncRNA shows strong nuclear enrichment and physically associates with chromatin-modifying complexes. Which functional hypothesis is most strongly supported by these data alone?

44 A qPCR experiment yields a standard curve with slope . What is the approximate amplification efficiency, and what does it indicate?

45 A two-point cross gives a recombination frequency of 12% between loci A and B, and 8% between B and C. A three-point cross between A and C gives 18%. What does this discrepancy most likely indicate?

46 In next-generation sequencing, a variant appears at 3% allele frequency in a tumor sample with 500x coverage. Why might this be a challenging call even at high depth?

47 A protein-coding gene undergoes alternative splicing producing an isoform lacking exon 5, which contains a stop codon in the retained transcript. The full-length mRNA is degraded, while the skipped isoform is stable. This regulation is best described as:

48 A researcher performs ChIP-seq for a transcription factor and finds strong binding peaks in regions lacking the canonical motif. Which explanation is most plausible?

49 In a bisulfite sequencing experiment, a CpG island shows near-complete conversion of cytosines to uracil except at specific sites. What do the unconverted cytosines indicate?

50 A quantitative trait shows broad-sense heritability but narrow-sense heritability . What does this gap most directly imply for a selective breeding program?

51 A GWAS identifies a significant SNP in an intergenic region far from any gene. Which follow-up interpretation is most scientifically sound?

52 During cloning, a researcher fails to obtain recombinant colonies despite successful ligation. The vector self-ligates efficiently. Which strategy most directly reduces vector self-ligation?

53 A single-cell RNA-seq dataset shows a cluster of cells with high mitochondrial gene content and low total counts. What is the most appropriate interpretation before downstream analysis?

54 A knockout mouse for a gene shows no phenotype, yet the gene is highly conserved across vertebrates. Which explanation best reconciles conservation with the absence of a phenotype?

55 In a codon optimization strategy for heterologous protein expression, replacing rare codons with frequent ones sometimes reduces protein solubility. What is the most likely mechanistic cause?

56 A researcher uses RNAi and observes off-target phenotypes. Which property of the siRNA most commonly drives these off-target effects?

57 A mutation in a splice donor site (GT) at an intron boundary is identified. Which outcome is LEAST likely to result from this mutation?

58 In differential expression analysis with limited replicates, why do methods like DESeq2 model counts with a negative binomial rather than a Poisson distribution?

59 A base editor (cytosine base editor) is used to install a C→T edit but produces unexpected edits at nearby cytosines within the target window. What is the primary cause?

60 A pedigree shows a trait transmitted only through mothers to all offspring, with variable severity among siblings. Which inheritance pattern and phenomenon best explain this?