This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Transcription Basics”.
1. What is the process of copying genetic information from a single strand of DNA into an RNA known as?
c) Reverse transcription
d) Reverse translation
Explanation: The process of copying a single strand of DNA into a strand of RNA is called as transcription. The process of transcription is the first stage in the central dogma of DNA.
2. During transcription, Adenosine forms a base pair with Uracil instead of Thymine.
Explanation: In DNA, the double hydrogen base pairing is seen between Adenine and Thymine. Likewise, the triple hydrogen base pairing is seen between Guanine and Cytosine. But Uracil is present in the place of Thymine in the single stranded structure of RNA. So, Adenosine forms a base pair with Uracil instead of Thymine.
3. Which of the following is the main characteristic difference between replication and transcription?
|I.||Duplication of both strands of DNA||Copying both the strands of DNA into a single strand of RNA|
|II.||Duplication of both strands of DNA||Copying a single strand of DNA into a single strand of RNA|
|III.||Duplication of a single strand of DNA||Copying both the strands of DNA into a single strand of RNA|
|IV.||Duplication of a single strand of DNA||Copying a single strand of DNA into a single strand of RNA|
Explanation: In the process of replication, the total DNA of an organism (double stranded helical structure) is duplicated. During transcription, a single strand of DNA is copied complementary to the single stranded RNA structure. This is the key difference between these two processes.
4. Both the strands of DNA are copied during the process of replication.
Explanation: If both the strands of DNA are copied into the RNA acting as a template strand, then coding of these RNA molecules into protein will become complex during the process of translation. Translation is the second stage during the central dogma of DNA. So, only a single strand of DNA is copied into the RNA for the synthesis of protein.
5. Which of the following is not a transcription unit of the DNA?
d) Structural gene
Explanation: The transcription unit of a DNA molecule consists of a promoter region, the structural gene and a terminator. A transcription unit consists of a sequential arrangement of nucleotides which are used to code for the RNA molecule during the process of transcription.
6. In which direction does the DNA dependent RNA polymerase catalyse the polymerisation reaction?
a) 3’ → 5’
c) Direction is dependent on the medium
d) 5’ → 3’
Explanation: The DNA dependent RNA polymerase is an enzyme which has the capability to catalyse the polymerisation reaction in the direction of 5’ → 3’ polarity. The other strand runs along the
3’ → 5’ direction of polarity is called as the template strand. Whereas, the 5’ → 3’ strand is called as the coding strand.
7. Which of the following is the initial “start site“ for the process of transcription?
d) Structural gene
Explanation: The promoter region which is present towards the 5’ end of the coding strand is the start site for transcription to occur. These are regions on the DNA where the RNA polymerase enzyme will bind. This leads to the process of transcription.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
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