Science of genetics – basic principles MCQs With Answer is a concise, student-focused review tailored for B.Pharm learners covering core genetics concepts essential to pharmacy practice. This introduction highlights DNA structure, genes, alleles, Mendelian inheritance, gene expression (transcription and translation), mutations, chromosomal behavior, genetic mapping, PCR, restriction enzymes, plasmids, and pharmacogenomics. Emphasis on practical relevance—drug response, metabolic variation, and gene-based therapies—helps bridge theory and clinical application. Clear, keyword-rich explanations build foundational knowledge for therapeutics, toxicology, and personalized medicine. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the fundamental structural form of DNA in cells?
- Single-stranded linear polymer
- Double helix of two antiparallel strands
- Triple helix of three parallel strands
- Circular single-stranded molecule
Correct Answer: Double helix of two antiparallel strands
Q2. Which nitrogenous base pairs with adenine in DNA?
- Cytosine
- Uracil
- Thymine
- Guanine
Correct Answer: Thymine
Q3. What is the central dogma of molecular biology?
- Translation → Transcription → Replication
- Replication → Translation → Transcription
- Transcription → Translation → Replication
- Replication → Transcription → Translation
Correct Answer: Replication → Transcription → Translation
Q4. During transcription, which enzyme synthesizes RNA from a DNA template?
- DNA polymerase
- RNA polymerase
- Reverse transcriptase
- Ribonuclease
Correct Answer: RNA polymerase
Q5. The genetic code is described as degenerate. What does this mean?
- One codon codes for multiple amino acids
- Multiple codons can code for the same amino acid
- Each codon codes for a unique tRNA molecule
- Codons are identical across species
Correct Answer: Multiple codons can code for the same amino acid
Q6. Which mutation type changes a single nucleotide leading to a different amino acid?
- Nonsense mutation
- Frameshift mutation
- Missense mutation
- Silent mutation
Correct Answer: Missense mutation
Q7. What does a frameshift mutation usually result from?
- Point substitution of a purine to purine
- Insertion or deletion not in multiples of three
- Synonymous codon change
- Loss of start codon only
Correct Answer: Insertion or deletion not in multiples of three
Q8. In Mendelian genetics, two alleles are identical in a homozygote. Which term describes the heterozygote phenotype halfway between two homozygotes?
- Dominance
- Incomplete dominance
- Codominance
- Epistasis
Correct Answer: Incomplete dominance
Q9. Which technique amplifies a specific DNA fragment exponentially?
- Sanger sequencing
- Northern blotting
- Polymerase chain reaction (PCR)
- Restriction fragment length polymorphism (RFLP)
Correct Answer: Polymerase chain reaction (PCR)
Q10. Which enzyme cuts DNA at specific recognition sequences producing fragments useful in cloning?
- DNA ligase
- Restriction endonuclease
- Topoisomerase
- DNA helicase
Correct Answer: Restriction endonuclease
Q11. What is linkage disequilibrium?
- Independent assortment of all genes
- Non-random association of alleles at two loci
- Complete absence of recombination
- Segregation of mitochondrial genes only
Correct Answer: Non-random association of alleles at two loci
Q12. Which process increases genetic diversity by exchanging chromosome segments between homologs?
- DNA methylation
- Recombination (crossing over)
- Transcriptional splicing
- Chromatin condensation
Correct Answer: Recombination (crossing over)
Q13. Which molecule carries amino acids to the ribosome during translation?
- mRNA
- rRNA
- tRNA
- snRNA
Correct Answer: tRNA
Q14. In prokaryotes, what sequence allows RNA polymerase to bind and initiate transcription?
- Origin of replication
- Promoter
- Polyadenylation signal
- Shine-Dalgarno sequence
Correct Answer: Promoter
Q15. Which term defines different forms of the same gene?
- Chromosomes
- Genomes
- Alleles
- Codons
Correct Answer: Alleles
Q16. Which type of RNA is a major structural and catalytic component of the ribosome?
- mRNA
- tRNA
- rRNA
- miRNA
Correct Answer: rRNA
Q17. Which chromosomal abnormality involves a segment of chromosome present in extra copies?
- Deletion
- Duplication
- Inversion
- Translocation
Correct Answer: Duplication
Q18. What is pharmacogenomics primarily concerned with?
- Environmental causes of disease
- Drug–gene interactions affecting response and toxicity
- Cellular metabolism of carbohydrates
- Design of medical devices
Correct Answer: Drug–gene interactions affecting response and toxicity
Q19. Which genetic element often carries antibiotic resistance genes and can transfer between bacteria?
- Chromosomal telomere
- Plasmid
- Centromere
- Histone
Correct Answer: Plasmid
Q20. In gene expression regulation, DNA methylation typically leads to:
- Increased transcription
- Gene silencing / decreased transcription
- Frameshift mutations
- Enhanced translation efficiency
Correct Answer: Gene silencing / decreased transcription
Q21. Which type of mutation creates a premature stop codon?
- Missense mutation
- Nonsense mutation
- Silent mutation
- Duplication mutation
Correct Answer: Nonsense mutation
Q22. Hardy-Weinberg equilibrium assumes all except which condition?
- No mutation
- Random mating
- Natural selection is strong
- Large population size
Correct Answer: Natural selection is strong
Q23. Which laboratory method separates DNA fragments by size using an electric field?
- Gel electrophoresis
- ELISA
- Flow cytometry
- Mass spectrometry
Correct Answer: Gel electrophoresis
Q24. Which is the start codon for translation in most organisms?
- UAA
- AUG
- UAG
- UGA
Correct Answer: AUG
Q25. What role does DNA ligase play in molecular cloning?
- Cleaves DNA at restriction sites
- Joins DNA fragments by forming phosphodiester bonds
- Amplifies DNA fragments
- Denatures double-stranded DNA
Correct Answer: Joins DNA fragments by forming phosphodiester bonds
Q26. A silent mutation changes a codon but does not alter the amino acid. Why?
- Because of codon redundancy in the genetic code
- Because tRNA sequence always changes
- Because transcription halts immediately
- Because ribosomes correct the mutation
Correct Answer: Because of codon redundancy in the genetic code
Q27. Which form of inheritance describes a trait determined by multiple genes each adding a small effect?
- Mendelian single-gene inheritance
- Polygenic inheritance
- Mitochondrial inheritance
- X-linked dominant inheritance
Correct Answer: Polygenic inheritance
Q28. Which assay detects specific RNA molecules to study gene expression?
- Northern blot
- Western blot
- Southern blot
- Eastern blot
Correct Answer: Northern blot
Q29. In prokaryotic translation initiation, which sequence positions the ribosome on mRNA?
- Kozak sequence
- Poly-A tail
- Shine-Dalgarno sequence
- Intronic splice site
Correct Answer: Shine-Dalgarno sequence
Q30. Which gene-editing tool uses RNA-guided endonuclease activity to create targeted DNA breaks?
- TALENs
- Zinc-finger nucleases
- CRISPR-Cas9
- RNAi machinery
Correct Answer: CRISPR-Cas9
