MCQOPTIONS
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MCQOPTIONS
This section includes 267 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The largest class of introns which are found in nuclear mRNA primary transcript is |
| A. | Spliceosomal introns |
| B. | Group I introns |
| C. | Group II introns |
| D. | Group IV introns |
| Answer» B. Group I introns | |
| 102. |
Which of the following is not involved in the post transcriptional processing of t-RNA? |
| A. | Base modulation |
| B. | Attachment of CCA arm |
| C. | Splicing |
| D. | Attachment of poly-A tail |
| Answer» E. | |
| 103. |
The genetic material of retroviruses such as HIV is |
| A. | DNA |
| B. | RNA |
| C. | protein |
| D. | all of these |
| Answer» C. protein | |
| 104. |
Incorrect statement about m-RNA |
| A. | Cap is added to the 5’ end |
| B. | Introns are removed and exons are spliced together |
| C. | Histone mRNAs lack 5’ cap |
| D. | Poly-A tail is added to the 3’ end |
| Answer» C. Histone mRNAs lack 5’ cap | |
| 105. |
Protein synthesis rates in prokaryotes are limited by the rate of mRNA synthesis. If RNA synthesis occurs at the rate of 50 nucleotides/sec, then rate of protein synthesis occurs at |
| A. | 10 amino acids/sec |
| B. | 17 amino acids/sec |
| C. | 25 amino acids/sec |
| D. | 50 amino acids/sec |
| Answer» C. 25 amino acids/sec | |
| 106. |
During RNA synthesis, the DNA template sequence 5'Tp Ap Gp Cp 3' Would be transcribed to produce which of the following RNA sequence? |
| A. | 5'-Ap Tp Cp Gp-3' |
| B. | 5'-Gp Cp Up Ap-3' |
| C. | 5'-Gp Cp Tp Ap-3' |
| D. | 5'-Ap Up Cp Gp-3' |
| Answer» C. 5'-Gp Cp Tp Ap-3' | |
| 107. |
DNA unwinding is done by |
| A. | Ligase |
| B. | Helicase |
| C. | Topoisomerase |
| D. | Hexonuclease |
| Answer» C. Topoisomerase | |
| 108. |
The two subassemblies of 26S proteasome are |
| A. | 20S core particle and 19S regulatory particle |
| B. | 20S regulatory particle and 19S core particle |
| C. | 18S core particle and 19S regulatory particle |
| D. | 20S core particle and 18S regulatory particle |
| Answer» B. 20S regulatory particle and 19S core particle | |
| 109. |
The termination codon is not |
| A. | AUG |
| B. | UAA |
| C. | UAG |
| D. | UGA |
| Answer» B. UAA | |
| 110. |
What does ligase do during replication of DNA? |
| A. | Synthesizes the lagging strand |
| B. | Makes copies of mRNA from DNA |
| C. | Joins nicks in DNA strands |
| D. | Digests mRNA when it is no longer needed |
| Answer» D. Digests mRNA when it is no longer needed | |
| 111. |
Which of the following is not necessary for protein synthesis to occur, once transcription is completed? |
| A. | tRNA |
| B. | Ribosomes |
| C. | mRNA |
| D. | DNA |
| Answer» E. | |
| 112. |
The type I enzyme(s) is/are |
| A. | Topoisomerases I and III |
| B. | Topoisomerases II |
| C. | Topoisomerase IV |
| D. | Topoisomerases I and IV |
| Answer» B. Topoisomerases II | |
| 113. |
An example of RNA-dependent DNA polymerase is |
| A. | Reverse transcriptase |
| B. | DNA ligase |
| C. | RNA polymerase I |
| D. | RNA polymerase II |
| Answer» B. DNA ligase | |
| 114. |
Which of the following statements regarding splicing in eukaryotes is correct? |
| A. | Several reactions in the splicing process involve hydrolysis of ATP |
| B. | Exons are spliced out and introns are retained in the mature mRNA transcript |
| C. | Splicing takes place in the cytosol |
| D. | Small nuclear RNAs are retained in the mature mRNA transcript |
| Answer» B. Exons are spliced out and introns are retained in the mature mRNA transcript | |
| 115. |
What is the function of messenger RNA? |
| A. | It carries amino acids |
| B. | It is a component of the ribosomes |
| C. | It is a direct copy of a gene |
| D. | It is the genetic material of some organisms |
| Answer» D. It is the genetic material of some organisms | |
| 116. |
The phenomenon of twisting around itself by a molecule to relieve helical stress is |
| A. | Supercoiling |
| B. | Coiling |
| C. | Elongation |
| D. | Compression |
| Answer» B. Coiling | |
| 117. |
The B-DNA structure found in solution is a |
| A. | left-handed double helix of antiparallel chains (10 bp/turn) |
| B. | right-handed double helix of antiparallel chains (∼10 bp/turn) |
| C. | left-handed zig-zag helix of antiparallel chains (10 bp/turn) |
| D. | right-handed double helix of parallel chains (∼10 bp/turn) |
| Answer» C. left-handed zig-zag helix of antiparallel chains (10 bp/turn) | |
| 118. |
Proteins contain __________ different amino acids, whereas DNA and RNA are composed of __________ different nucleotides |
| A. | 20,64 |
| B. | 3,20 |
| C. | 4,20 |
| D. | 20,4 |
| Answer» E. | |
| 119. |
The extra chromosomal, self-replicating, double stranded, closed, circular DNA molecules are called |
| A. | Viruses |
| B. | Phages |
| C. | Chloroplasts |
| D. | Plasmids |
| Answer» E. | |
| 120. |
Which of the following is true about DNA polymerase? |
| A. | It can synthesize DNA in the 5’ to 3’ direction |
| B. | It can synthesize DNA in the 3’ to 5’ direction |
| C. | It can synthesize mRNA in the 3’ to 5’ direction |
| D. | It can synthesize mRNA in the 5’ to 3’ direction |
| Answer» B. It can synthesize DNA in the 3’ to 5’ direction | |
| 121. |
Which of the following are not DNA viruses? |
| A. | Hepatitis B virus |
| B. | Influenza A virus |
| C. | CMV virus |
| D. | Parvovirus |
| Answer» C. CMV virus | |
| 122. |
The role of small nuclear RNAs in protein synthesis is |
| A. | It translates genetic code to a specific amino acid |
| B. | It modifies mRNA molecules prior to protein synthesis |
| C. | It provides genetic blueprint for the protein |
| D. | It catalyzes the process |
| Answer» C. It provides genetic blueprint for the protein | |
| 123. |
The sequences of the recombination sites recognized by site-specific recombinases are |
| A. | Partially asymmetric |
| B. | Partially symmetric |
| C. | Symmetric |
| D. | Palindromic |
| Answer» B. Partially symmetric | |
| 124. |
What is the name given to the points at which a DNA helix is unwound and new strands develop? |
| A. | Replication origins |
| B. | Replication forks |
| C. | Leading strands |
| D. | Okazaki fragments |
| Answer» C. Leading strands | |
| 125. |
The site on a bacterial chromosome that marks the termination point for chromosome replication is called |
| A. | ter |
| B. | a stop codon. |
| C. | a stem-loop |
| D. | pau |
| Answer» B. a stop codon. | |
| 126. |
Which of the following in DNA replication and transcription are common? |
| A. | incorporation of deoxynucleotides |
| B. | utilization the same enzyme |
| C. | synthesis in the 5'-3' direction |
| D. | none of the above |
| Answer» D. none of the above | |
| 127. |
The lac operon contains the z, y and a structural genes |
| A. | encoding p-galactosidase, galactose permeases and thio-galactosidase transacetylase respectively |
| B. | encoding p-galactosidase and galactose permeases |
| C. | encoding P-galactosidase only |
| D. | None of the above |
| Answer» B. encoding p-galactosidase and galactose permeases | |
| 128. |
Who's X-ray work aided Watson and Crick in their discovery of the double helix? |
| A. | W.H. Bragg |
| B. | R. Franklin |
| C. | L. Pauling |
| D. | Leaderberg |
| Answer» C. L. Pauling | |
| 129. |
How does ethidium bromide interact with DNA? |
| A. | It binds to adenine |
| B. | It binds to phosphate |
| C. | It intercalates between bases |
| D. | It does not interact |
| Answer» D. It does not interact | |
| 130. |
An RNA primer is synthesized by |
| A. | DNA helicases |
| B. | ligase |
| C. | DNA topoisomerase |
| D. | primase |
| Answer» E. | |
| 131. |
The pathway of a tRNA during polypeptide elongation on the ribosome is |
| A. | A site → P site → E site |
| B. | P site → entry site → exit site |
| C. | A site → P site → entry site |
| D. | P site → A site → E site |
| Answer» B. P site → entry site → exit site | |
| 132. |
A nicked RNA molecule can be ligated by |
| A. | T4 RNA ligase |
| B. | DNA polymerase |
| C. | T4 DNA ligase |
| D. | all of these |
| Answer» D. all of these | |
| 133. |
The site of protein synthesis is |
| A. | Ribosome |
| B. | Nucleus |
| C. | Endoplasmic reticulum |
| D. | Chromosome |
| Answer» B. Nucleus | |
| 134. |
Phosphorus is taken up by the cell during the process of |
| A. | carbohydrate synthesis. |
| B. | protein synthesis, |
| C. | lipid synthesis. |
| D. | ATP synthesis. |
| Answer» E. | |
| 135. |
Which of the following catalyzes ADP-ribosylation of a diphthamide residue? |
| A. | Chloramphenicol |
| B. | Cycloheximide |
| C. | Diphtheria toxin |
| D. | Ricin |
| Answer» D. Ricin | |
| 136. |
Eukaryotes differ from prokaryote in mechanism of DNA replication due to |
| A. | Use of DNA primer rather than RNA primer |
| B. | Different enzyme for synthesis of lagging and leading strand |
| C. | Discontinuous rather than semi-discontinuous replication |
| D. | Unidirectional rather than semi-discontinuous replication |
| Answer» D. Unidirectional rather than semi-discontinuous replication | |
| 137. |
What is the average size (in bp) of a mature t-RNA? |
| A. | 80 bp |
| B. | 100 bp |
| C. | 120 bp |
| D. | 140 bp |
| Answer» B. 100 bp | |
| 138. |
DNA replication results in |
| A. | two completely new DNA molecules |
| B. | two DNA molecules such that each one contains a strand of the original |
| C. | one new DNA molecules 1 old molecule |
| D. | one new molecule of RNA |
| Answer» C. one new DNA molecules 1 old molecule | |
| 139. |
Short interspersed elements are about |
| A. | 100 to 300 bp long |
| B. | 200 to 400 bp long |
| C. | 10 to 100 bp long |
| D. | 6000 to 8000 bp long |
| Answer» B. 200 to 400 bp long | |
| 140. |
Which enzyme catalyzes the elongation of DNA molecules? |
| A. | DNA polymerase |
| B. | Helicase |
| C. | DNA ligase |
| D. | Primase |
| Answer» B. Helicase | |
| 141. |
First evident that DNA is genetic material comes from the experiment of Griffith is |
| A. | transduction |
| B. | transformation |
| C. | replication |
| D. | translation |
| Answer» C. replication | |
| 142. |
An enzyme that recognizes foreign DNA, and results in a cut in that DNA is called |
| A. | transposase |
| B. | helicase |
| C. | reverse transcriptase |
| D. | restriction endonuclease |
| Answer» E. | |
| 143. |
The enzyme photolyase is used in what method of repair? |
| A. | Base excision |
| B. | Photo reactivation |
| C. | Nucleotide excision |
| D. | None of these |
| Answer» C. Nucleotide excision | |
| 144. |
Which of the following statements about viruses is true? |
| A. | They contain DNA |
| B. | They contain RNA |
| C. | They contain protein |
| D. | They are susceptible to lipid solvents |
| Answer» D. They are susceptible to lipid solvents | |
| 145. |
The genetic code translated the language of |
| A. | Proteins into that of RNA |
| B. | Amino acids into that of RNA |
| C. | RNA into that of proteins |
| D. | RNA into that of DNA |
| Answer» D. RNA into that of DNA | |
| 146. |
If the mutation has a negligible effect on the function of a gene, it is known as a |
| A. | Silent mutation |
| B. | Frame shift mutation |
| C. | Substitution mutation |
| D. | Insertion mutation |
| Answer» B. Frame shift mutation | |
| 147. |
A point mutation that replaces a purine with another purine, or a pyrimidine with another pyramidine |
| A. | Nonsense mutation |
| B. | Silent mutation |
| C. | Transition mutation |
| D. | Transversion |
| Answer» D. Transversion | |
| 148. |
The main function of t-RNA is |
| A. | Proof reading |
| B. | Inhibits protein synthesis |
| C. | Identifies amino acids and transport them to ribosomes |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 149. |
Which of the following occurs between particular short sequences present on otherwise dissimilar parental molecules? |
| A. | Homologous genetic recombination |
| B. | Site specific recombination |
| C. | Non-homologous recombination |
| D. | Replicative recombination |
| Answer» C. Non-homologous recombination | |
| 150. |
In DNA, guanine pairs with |
| A. | Adenine |
| B. | Cytosine |
| C. | Thymine |
| D. | Uracil |
| Answer» C. Thymine | |