MCQ on Molecular Genetics - Part - 2

1. Which technique is best suited for determining the entire nucleotide sequence of a genome?
A) PCR
B) Sanger sequencing
C) Next-generation sequencing (NGS)
D) DNA microarray
Answer: C
Rationale: NGS allows rapid and large-scale sequencing compared to Sanger sequencing.

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2. CRISPR-Cas9 system uses which molecule as a guide to target DNA?
A) Protein sequence
B) RNA sequence
C) DNA sequence
D) Ribosome sequence
Answer: B
Rationale: A guide RNA (gRNA) directs Cas9 to the complementary DNA site.

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3. The Human Genome Project was officially completed in:
A) 1995
B) 2000
C) 2003
D) 2005
Answer: C
Rationale: The Human Genome Project was declared complete in 2003.

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4. Epigenetic regulation primarily involves:
A) DNA replication errors
B) DNA methylation and histone modification
C) Mutation in coding sequences
D) Protein denaturation
Answer: B
Rationale: Epigenetics controls gene expression without altering DNA sequence.

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5. The “one gene–one enzyme” hypothesis was proposed by:
A) Beadle and Tatum
B) Watson and Crick
C) Jacob and Monod
D) Hershey and Chase
Answer: A
Rationale: Beadle and Tatum demonstrated that genes control enzymes in metabolic pathways.

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6. Which of the following is NOT a component of a plasmid cloning vector?
A) Origin of replication
B) Selectable marker
C) Multiple cloning site
D) Ribosome
Answer: D
Rationale: Plasmid vectors contain origin, marker, and MCS, but ribosomes are not part of plasmids.

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7. Southern blotting is used to detect:
A) RNA
B) Proteins
C) DNA
D) Lipids
Answer: C
Rationale: Southern blotting identifies DNA sequences, while Northern is for RNA and Western for proteins.

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8. Which enzyme is responsible for proofreading during DNA replication?
A) DNA helicase
B) DNA ligase
C) DNA polymerase
D) Primase
Answer: C
Rationale: DNA polymerase has 3’→5’ exonuclease activity for proofreading.

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9. In prokaryotes, transcription and translation are coupled because:
A) Both occur in the cytoplasm without nuclear separation
B) Ribosomes are attached to DNA directly
C) Transcription stops before translation starts
D) RNA processing is extensive
Answer: A
Rationale: In bacteria, mRNA is translated by ribosomes while it is still being transcribed.

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10. Which scientist coined the term “gene”?
A) Wilhelm Johannsen
B) Gregor Mendel
C) Thomas Hunt Morgan
D) Francis Crick
Answer: A
Rationale: Johannsen introduced the term “gene” in 1909 to describe hereditary units.