Part 5: Central Dogma & Transcription (25 MCQs)
Part 5: Central Dogma & Transcription (25 MCQs)
Q101. The central dogma of molecular biology was proposed by:
a) Watson
b) Crick
c) Griffith
d) Avery
Answer: b
- b) Correct: Francis Crick proposed central dogma (DNA → RNA → Protein).
- a) Watson co-discovered DNA structure.
- c, d) Inheritance experiments, not central dogma.
Q102. Central dogma involves flow of genetic information from:
a) Protein → RNA → DNA
b) DNA → RNA → Protein
c) RNA → DNA → Protein
d) RNA → Protein → DNA
Answer: b
- b) Correct: Normal flow = DNA → RNA → Protein.
- c) Happens in retroviruses, not general.
Q103. The process of copying genetic information from DNA to RNA is called:
a) Translation
b) Replication
c) Transcription
d) Transformation
Answer: c
- c) Correct: Transcription = DNA → RNA synthesis.
Q104. Enzyme responsible for transcription is:
a) DNA polymerase
b) RNA polymerase
c) Ligase
d) Telomerase
Answer: b
- b) Correct: RNA polymerase synthesizes RNA using DNA template.
Q105. In prokaryotes, RNA polymerase has:
a) One subunit only
b) Four core subunits + σ factor
c) Six identical subunits
d) No sigma factor
Answer: b
- b) Correct: RNA polymerase = α₂, β, β′ core + σ factor.
Q106. Sigma (σ) factor in transcription helps in:
a) Chain elongation
b) Chain termination
c) Initiation by promoter recognition
d) Proofreading
Answer: c
- c) Correct: σ factor helps RNA polymerase recognize promoter and initiate.
Q107. Template strand in transcription is also called:
a) Coding strand
b) Sense strand
c) Non-coding or antisense strand
d) mRNA strand
Answer: c
- c) Correct: Template = antisense strand.
- a, b) Coding/sense strand is non-template.
Q108. Coding strand of DNA has the same sequence as:
a) mRNA (except T replaced by U)
b) tRNA
c) rRNA
d) Antisense strand
Answer: a
- a) Correct: Coding strand = same as mRNA (U instead of T).
Q109. Promoter region is located:
a) On mRNA
b) At 3′ end of DNA
c) Upstream of transcription unit
d) Downstream of terminator
Answer: c
- c) Correct: Promoter lies upstream of gene.
Q110. Which sequence is called TATA box in eukaryotes?
a) GC-rich sequence
b) ATG codon
c) TATAAA consensus sequence
d) Shine-Dalgarno sequence
Answer: c
- c) Correct: TATA box (TATAAA) = eukaryotic promoter.
Q111. In prokaryotes, promoter recognition occurs at:
a) −10 and −35 regions
b) +1 region only
c) Terminator
d) Enhancer
Answer: a
- a) Correct: −10 (Pribnow box) and −35 regions are prokaryotic promoters.
Q112. Which strand serves as the template for RNA synthesis?
a) Sense strand
b) Coding strand
c) Antisense strand
d) Both strands
Answer: c
- c) Correct: Antisense strand serves as template.
Q113. The first nucleotide of transcribed RNA is designated as:
a) −1
b) +1
c) 0
d) +10
Answer: b
- b) Correct: Transcription initiation site = +1.
Q114. Rho factor in prokaryotes is involved in:
a) Initiation
b) Elongation
c) Termination
d) Proofreading
Answer: c
- c) Correct: Rho protein causes termination in some prokaryotic genes.
Q115. Eukaryotic RNA polymerase II transcribes:
a) rRNA
b) tRNA
c) mRNA
d) snRNA only
Answer: c
- c) Correct: RNA Pol II → mRNA.
- a) rRNA → RNA Pol I.
- b) tRNA → RNA Pol III.
Q116. Which RNA polymerase transcribes rRNA in eukaryotes?
a) RNA Pol I
b) RNA Pol II
c) RNA Pol III
d) RNA Pol IV
Answer: a
- a) Correct: RNA Pol I → rRNA (except 5S rRNA).
Q117. Which RNA polymerase transcribes tRNA in eukaryotes?
a) RNA Pol I
b) RNA Pol II
c) RNA Pol III
d) RNA Pol IV
Answer: c
- c) Correct: RNA Pol III → tRNA and 5S rRNA.
Q118. In eukaryotes, primary transcript undergoes:
a) Capping
b) Tailing
c) Splicing
d) All of the above
Answer: d
- d) Correct: hnRNA → processed by 5′ cap, 3′ poly-A tail, splicing.
Q119. 5′ capping involves addition of:
a) Adenine
b) Guanine (methylated GTP)
c) Uracil
d) Cytosine
Answer: b
- b) Correct: 7-methyl guanosine cap is added at 5′ end.
Q120. 3′ tailing in mRNA processing involves addition of:
a) Poly-C tail
b) Poly-G tail
c) Poly-A tail
d) Poly-U tail
Answer: c
- c) Correct: Poly-A tail (~200 As) added at 3′ end.
Q121. Splicing removes:
a) Exons
b) Introns
c) Promoters
d) Enhancers
Answer: b
- b) Correct: Introns are removed, exons joined.
Q122. Splicing occurs in:
a) Prokaryotes
b) Eukaryotes
c) Both
d) Only viruses
Answer: b
- b) Correct: Splicing = eukaryotic process (prokaryotes lack introns).
Q123. Alternative splicing allows:
a) Multiple proteins from one gene
b) Only one protein per gene
c) RNA degradation
d) Faster replication
Answer: a
- a) Correct: Alternative splicing → different proteins from same gene.
Q124. In prokaryotes, mRNA is:
a) Monocistronic
b) Polycistronic
c) Without coding sequence
d) Non-functional
Answer: b
- b) Correct: Prokaryotic mRNA = polycistronic (codes for multiple proteins).
Q125. In eukaryotes, mRNA is generally:
a) Polycistronic
b) Monocistronic
c) Non-coding
d) RNA only
Answer: b
- b) Correct: Eukaryotic mRNA = monocistronic (one gene → one protein).
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