Molecular Biology – Transcription: NEET MCQs with Answers

15 free questions on Molecular Biology – Transcription for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Transcription

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Question 1

Previous-year question
Name the enzyme that facilitates the opening of the DNA helix during transcription. [NEET 2020]
  1. DNA helicase
  2. DNA polymerase
  3. RNA polymerase
  4. DNA ligase
Show answer
Answer: (C) RNA polymerase
Explanation: During transcription the RNA polymerase itself unwinds a short stretch of the double helix as it moves along the template, and the helix closes again behind it. A separate helicase is not required.

Question 2

Previous-year question
AGGTATCGCAT is a sequence from the coding strand of a gene. What will be the corresponding sequence of the transcribed mRNA? [NEET 2018]
  1. AGGUAUCGCAU
  2. UGGTUTCGCAT
  3. UCCAUAGCGUA
  4. ACCUAUGCGAU
Show answer
Answer: (A) AGGUAUCGCAU
Explanation: The mRNA has the same sequence as the coding strand with uracil substituted for thymine, because both are complementary to the template strand. Hence AGGTATCGCAT is transcribed as AGGUAUCGCAU.

Question 3

Previous-year question
Which of the following RNAs should be the most abundant in an animal cell? [NEET 2017]
  1. tRNA
  2. mRNA
  3. miRNA
  4. rRNA
Show answer
Answer: (D) rRNA
Explanation: Ribosomal RNA constitutes roughly 80% of the total cellular RNA because each cell contains thousands of ribosomes, each built largely from rRNA.

Question 4

Previous-year question
Spliceosomes are not found in the cells of [NEET 2017]
  1. Fungi
  2. Animals
  3. Bacteria
  4. Plants
Show answer
Answer: (C) Bacteria
Explanation: Spliceosomes remove introns from hnRNA, a process needed only where genes are split. Bacterial genes lack introns, so bacteria have no spliceosomes; all the eukaryotic groups listed possess them.

Question 5

Previous-year question
Select the correct option regarding the direction of RNA synthesis and the direction in which the template DNA strand is read. [AIPMT 2014]
  1. RNA synthesis 5'→3'; template read 3'→5'
  2. RNA synthesis 3'→5'; template read 5'→3'
  3. RNA synthesis 5'→3'; template read 5'→3'
  4. RNA synthesis 3'→5'; template read 3'→5'
Show answer
Answer: (A) RNA synthesis 5'→3'; template read 3'→5'
Explanation: RNA polymerase adds ribonucleotides to the free 3'-OH of the growing chain, so RNA is made 5'→3'. Because the two chains must be antiparallel, the template strand is read in the 3'→5' direction.

Question 6

Previous-year question
Which one of the following is wrongly matched? [AIPMT 2014]
  1. Transcription – writing information from DNA to tRNA
  2. Translation – using information in mRNA to make protein
  3. Repressor protein – binds to the operator to stop enzyme synthesis
  4. Operon – structural genes, operator and promoter
Show answer
Answer: (A) Transcription – writing information from DNA to tRNA
Explanation: Transcription is the copying of information from DNA into messenger RNA, not into tRNA. The remaining three statements are correctly matched.

Question 7

Previous-year question
The process of transfer of genetic information from DNA to RNA/formation of RNA from DNA is [AIPMT 1991]
  1. transversion
  2. transcription
  3. translation
  4. translocation
Show answer
Answer: (B) transcription
Explanation: Transcription is the transfer of genetic information from DNA to RNA, i.e. the formation of RNA on a DNA template. Both strands of DNA do not transcribe RNA — only the template strand is copied.
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Question 8

Previous-year question
DNA template sequence of CTGATAGC is transcribed over mRNA as [AIPMT 1994]
  1. GUCTUCG
  2. GACUAUCG
  3. GAUTATUG
  4. UACTATCU
Show answer
Answer: (B) GACUAUCG
Explanation: During transcription the complementary mRNA is formed on the DNA template with uracil in place of thymine. The complement of CTGATAGC is therefore GACUAUCG.

Question 9

Previous-year question
Reverse transcriptase is [AIPMT 1994]
  1. RNA dependent RNA polymerase
  2. DNA dependent DNA polymerase
  3. DNA dependent DNA polymerase
  4. RNA dependent DNA polymerase
Show answer
Answer: (D) RNA dependent DNA polymerase
Explanation: Reverse transcriptase is an RNA-dependent DNA polymerase discovered by Temin and Baltimore. By making DNA from an RNA template it modifies the central dogma to RNA → DNA → RNA → Protein.

Question 10

Previous-year question
If the sequence of bases in DNA is ATTCGATG, then the sequence of bases in its transcript will be [AIPMT 1995]
  1. CAUCGAAU
  2. UAAGCUAC
  3. GUAGCUUA
  4. AUUCGAUG
Show answer
Answer: (B) UAAGCUAC
Explanation: Transcription synthesises mRNA complementary to the DNA template, with uracil replacing thymine. The complement of ATTCGATG is therefore UAAGCUAC.

Question 11

Previous-year question
In split genes, the coding sequences are called [AIPMT 1995]
  1. introns
  2. operons
  3. exons
  4. cistrons
Show answer
Answer: (C) exons
Explanation: In split genes of higher organisms the coding regions are called exons, because they are expressed and appear in the mature mRNA. The intervening non-coding regions are the introns.

Question 12

Previous-year question
Gene and cistron words are sometimes used synonymously because [AIPMT 2001]
  1. one cistron contains many genes
  2. one gene contains many cistrons
  3. one gene contains one cistron
  4. one gene contains no cistron
Show answer
Answer: (C) one gene contains one cistron
Explanation: A cistron is a segment of DNA that codes for one polypeptide. Since a gene is the basic unit of heredity that determines a particular character through a polypeptide, one gene generally contains one cistron and the two terms are used synonymously.

Question 13

Previous-year question
In which direction mRNA is synthesised on DNA template? [AIPMT 2001]
  1. 5'→3'
  2. 3'→5'
  3. Both (a) and (b)
  4. Any of above
Show answer
Answer: (A) 5'→3'
Explanation: RNA polymerase synthesises mRNA only in the 5'→3' direction, reading the DNA template in the 3'→5' direction, because nucleotides can be added only to a free 3'-OH end.

Question 14

Previous-year question
Which of the following reunites the exon segments after RNA splicing? [AIPMT 2002]
  1. RNA polymerase
  2. RNA primase
  3. RNA ligase
  4. RNA protease
Show answer
Answer: (C) RNA ligase
Explanation: RNA ligase reunites the exon segments after the introns have been excised during RNA splicing, producing the continuous coding sequence of the mature mRNA.

Question 15

Previous-year question
Exon part of mRNAs have code for [AIPMT 2002]
  1. protein
  2. lipid
  3. carbohydrate
  4. phospholipid
Show answer
Answer: (A) protein
Explanation: Exons are the coding stretches of bases that specify amino acids and are retained in the mature mRNA. The intervening non-coding stretches, called introns, are removed during splicing.

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