Genes MCQs With Answer

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Genes MCQs With Answer is a focused resource for B. Pharm students covering essential concepts of gene structure, DNA replication, transcription, translation, mutations, pharmacogenomics and gene therapy. This concise, keyword-rich introduction prepares you for clinical and laboratory aspects such as PCR, SNP analysis, enzyme polymorphisms (CYP450), sequencing and epigenetic regulation. Each question is designed to deepen understanding relevant to drug action, adverse reactions and personalized medicine. Clear explanations reinforce molecular mechanisms, diagnostic tools and therapeutic applications important in pharmacy practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the basic unit of heredity that carries information in the form of DNA?

  • Chromatin
  • Gene
  • Chromosome
  • Genome

Correct Answer: Gene

Q2. Which nucleotide base pairs with adenine in DNA?

  • Uracil
  • Cytosine
  • Thymine
  • Guanine

Correct Answer: Thymine

Q3. During DNA replication, which enzyme synthesizes the new DNA strand?

  • RNA polymerase
  • DNA ligase
  • DNA polymerase
  • Helicase

Correct Answer: DNA polymerase

Q4. The start codon in mRNA that initiates translation is:

  • UAA
  • AUG
  • UGA
  • UAG

Correct Answer: AUG

Q5. A single nucleotide polymorphism (SNP) is best described as:

  • A change in chromosome number
  • A small insertion or deletion causing frameshift
  • A variation at a single base position in the genome
  • Loss of a large chromosomal segment

Correct Answer: A variation at a single base position in the genome

Q6. Which mutation type results in a premature stop codon?

  • Missense mutation
  • Nonsense mutation
  • Silent mutation
  • Frame-preserving insertion

Correct Answer: Nonsense mutation

Q7. In prokaryotes, the ribosome binding site is known as:

  • TATA box
  • Poly-A tail
  • Shine-Dalgarno sequence
  • Spliceosome

Correct Answer: Shine-Dalgarno sequence

Q8. Epigenetic modification that typically reduces gene expression is:

  • Histone acetylation
  • DNA methylation
  • mRNA capping
  • Ribosomal methylation

Correct Answer: DNA methylation

Q9. Which enzyme is essential for separating DNA strands prior to replication?

  • Topoisomerase
  • Helicase
  • Ligase
  • Primase

Correct Answer: Helicase

Q10. Pharmacogenomics primarily studies the effect of genetic variation on:

  • Pathogen virulence
  • Drug absorption only
  • Drug response and toxicity
  • Dietary deficiencies

Correct Answer: Drug response and toxicity

Q11. CYP450 enzymes are important in pharmacy because they:

  • Encode structural proteins
  • Metabolize many drugs
  • Form cell membranes
  • Carry oxygen in blood

Correct Answer: Metabolize many drugs

Q12. Which type of RNA carries amino acids to the ribosome?

  • mRNA
  • tRNA
  • rRNA
  • snRNA

Correct Answer: tRNA

Q13. A missense mutation causes:

  • No change in amino acid sequence
  • A change of one amino acid in the protein
  • An early translation termination
  • Complete gene deletion

Correct Answer: A change of one amino acid in the protein

Q14. Which technique amplifies a specific DNA fragment exponentially?

  • Southern blot
  • Sanger sequencing
  • Polymerase Chain Reaction (PCR)
  • Western blot

Correct Answer: Polymerase Chain Reaction (PCR)

Q15. In eukaryotes, non-coding sequences removed from pre-mRNA are called:

  • Exons
  • Introns
  • Promoters
  • Enhancers

Correct Answer: Introns

Q16. The genetic code is described as degenerate because:

  • One codon codes for multiple amino acids
  • Multiple codons can code for the same amino acid
  • Codons are ambiguous across species
  • Codons frequently mutate

Correct Answer: Multiple codons can code for the same amino acid

Q17. Hardy-Weinberg equilibrium assumes all of the following except:

  • No migration
  • No mutation
  • Random mating
  • Strong natural selection

Correct Answer: Strong natural selection

Q18. Which DNA repair mechanism removes and replaces mismatched bases after replication?

  • Base excision repair
  • Nucleotide excision repair
  • Mismatch repair
  • Homologous recombination

Correct Answer: Mismatch repair

Q19. A frameshift mutation is usually caused by:

  • Substitution of one base
  • Insertion or deletion not in multiples of three
  • DNA methylation changes
  • Silent codon change

Correct Answer: Insertion or deletion not in multiples of three

Q20. Which technique detects specific DNA sequences in a sample using labeled probes?

  • Northern blot
  • ELISA
  • Southern blot
  • Mass spectrometry

Correct Answer: Southern blot

Q21. In pharmacogenetics, an ultra-rapid metabolizer phenotype often results from:

  • Gene deletion
  • Gene duplication or increased activity variant
  • Complete loss-of-function variant
  • Somatic mutation only

Correct Answer: Gene duplication or increased activity variant

Q22. CRISPR-Cas9 is primarily used for:

  • Protein purification
  • Precise genome editing
  • Measuring gene expression
  • mRNA splicing

Correct Answer: Precise genome editing

Q23. Which of the following is a viral vector commonly used for gene therapy?

  • pBR322 plasmid
  • Adeno-associated virus (AAV)
  • Yeast artificial chromosome
  • Shuttle vector

Correct Answer: Adeno-associated virus (AAV)

Q24. MicroRNAs (miRNAs) regulate gene expression by:

  • Enhancing transcription
  • Binding and degrading target mRNA or inhibiting translation
  • Altering DNA methylation patterns directly
  • Promoting ribosomal biogenesis

Correct Answer: Binding and degrading target mRNA or inhibiting translation

Q25. Which region of a gene contains the binding site for RNA polymerase in eukaryotes?

  • Enhancer
  • Promoter
  • Exon
  • Poly-A signal

Correct Answer: Promoter

Q26. A heterozygous genotype means:

  • Both alleles at a locus are identical
  • Alleles are different at a locus
  • The gene is on the X chromosome only
  • Gene is not expressed

Correct Answer: Alleles are different at a locus

Q27. Which assay quantifies mRNA levels to measure gene expression?

  • Western blot
  • qRT-PCR
  • Chromatography
  • ELISA

Correct Answer: qRT-PCR

Q28. Which type of inheritance is characterized by males being affected more frequently than females?

  • Autosomal dominant
  • X-linked recessive
  • Autosomal recessive

Correct Answer: X-linked recessive

Q29. Restriction enzymes are used in molecular cloning to:

  • Join DNA fragments
  • Cut DNA at specific sequences
  • Amplify DNA sequences
  • Sequence DNA

Correct Answer: Cut DNA at specific sequences

Q30. Which genetic test is most useful for detecting single-gene disorders with known mutations?

  • Whole genome sequencing
  • Targeted mutation analysis
  • Chromosomal karyotype
  • Proteomic profiling

Correct Answer: Targeted mutation analysis

Q31. In translation, the ribosome moves along mRNA in which direction?

  • 3′ to 5′
  • 5′ to 3′
  • Both directions simultaneously
  • It remains stationary

Correct Answer: 5′ to 3′

Q32. Gene cloning commonly uses plasmids because they:

  • Are single-stranded DNA
  • Cannot replicate in bacteria
  • Carry selectable markers and replicate independently
  • Are degraded quickly in cells

Correct Answer: Carry selectable markers and replicate independently

Q33. Loss-of-function mutations typically produce which phenotype in autosomal recessive disorders?

  • Disease only in heterozygotes
  • Disease in homozygotes
  • Overexpression of protein
  • Always lethal in carriers

Correct Answer: Disease in homozygotes

Q34. Which method sequences DNA by incorporating chain-terminating nucleotides?

  • Next-generation sequencing
  • Sanger sequencing
  • Microarray hybridization
  • RFLP analysis

Correct Answer: Sanger sequencing

Q35. Linkage disequilibrium refers to:

  • Random association of alleles
  • Non-random association of alleles at different loci
  • Complete independence of loci
  • Equal allele frequencies

Correct Answer: Non-random association of alleles at different loci

Q36. Which chromosomal DNA is inherited almost exclusively from the mother?

  • Y chromosome
  • Mitochondrial DNA
  • Autosomal DNA
  • X chromosome

Correct Answer: Mitochondrial DNA

Q37. Antisense oligonucleotides act by:

  • Increasing DNA replication
  • Binding target mRNA to block translation
  • Promoting protein folding
  • Cleaving proteins directly

Correct Answer: Binding target mRNA to block translation

Q38. Which term describes a variant that changes phenotype only under certain environmental conditions?

  • Pleiotropic variant
  • Conditional mutation
  • Silent polymorphism
  • Constitutive allele

Correct Answer: Conditional mutation

Q39. In recombinant DNA technology, ligase is used to:

  • Cut DNA at restriction sites
  • Synthesize RNA primers
  • Join DNA fragments by forming phosphodiester bonds
  • Denature double-stranded DNA

Correct Answer: Join DNA fragments by forming phosphodiester bonds

Q40. A haplotype is best defined as:

  • A single allele at one locus
  • A set of DNA variations that tend to be inherited together
  • The number of chromosomes in a cell
  • A protein complex in the nucleus

Correct Answer: A set of DNA variations that tend to be inherited together

Q41. Which of the following is an application of pharmacogenomics in clinical pharmacy?

  • Predicting drug-drug interactions only
  • Personalizing drug dose based on genotype
  • Measuring blood pressure
  • Standardizing one dose for all patients

Correct Answer: Personalizing drug dose based on genotype

Q42. Southern blotting detects:

  • Proteins
  • RNA transcripts
  • Specific DNA sequences
  • Metabolites

Correct Answer: Specific DNA sequences

Q43. Imprinting refers to gene expression that depends on:

  • Environmental temperature
  • Which parent the allele was inherited from
  • Random somatic mutation
  • mRNA half-life only

Correct Answer: Which parent the allele was inherited from

Q44. Which polymerase is commonly used in PCR due to heat stability?

  • DNA polymerase I
  • Taq polymerase
  • Reverse transcriptase
  • RNA polymerase II

Correct Answer: Taq polymerase

Q45. A silent mutation results in:

  • No change in the encoded amino acid
  • A premature stop codon
  • Loss of gene copy
  • A frameshift

Correct Answer: No change in the encoded amino acid

Q46. Which term describes one complete set of chromosomes in a cell?

  • Allele
  • Genotype
  • Haploid genome
  • Phenotype

Correct Answer: Haploid genome

Q47. Therapy that introduces functional copies of a gene to treat genetic disease is called:

  • Enzyme replacement therapy
  • Gene therapy
  • Small-molecule therapy
  • Immunotherapy

Correct Answer: Gene therapy

Q48. Which of the following best describes a dominant negative mutation?

  • A mutated protein enhances normal protein function
  • Mutated protein interferes with function of wild-type protein
  • Mutation only affects noncoding DNA
  • Mutation leads to complete loss of gene transcription

Correct Answer: Mutated protein interferes with function of wild-type protein

Q49. Which lab technique separates DNA fragments by size using an electric field?

  • Gel electrophoresis
  • Flow cytometry
  • Mass spectrometry
  • Immunoprecipitation

Correct Answer: Gel electrophoresis

Q50. Pharmacogenetic testing for HLA-B*57:01 is clinically important to predict risk of:

  • Warfarin bleeding
  • Abacavir hypersensitivity
  • Statin-induced myopathy
  • ACE inhibitor cough

Correct Answer: Abacavir hypersensitivity

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