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.
| 201. |
How many t-RNAs are required to translate all 61 codons? |
| A. | 31 |
| B. | 32 |
| C. | 30 |
| D. | 29 |
| Answer» C. 30 | |
| 202. |
The type of topoisomerases that can introduce negative supercoils is |
| A. | Type I |
| B. | Type II |
| C. | Type III |
| D. | Type IV |
| Answer» C. Type III | |
| 203. |
Which of the following histones bind to linker DNA? |
| A. | H1 |
| B. | H2A |
| C. | H2B |
| D. | H3 |
| Answer» B. H2A | |
| 204. |
Recombinational repair is often due to |
| A. | Incorporation of many incorrect nucleotides by DNA pol |
| B. | Many cystidine dimer and associated large gaps in a strand |
| C. | Many thymidine dimer formation and associated large gaps in a strand |
| D. | All of these |
| Answer» D. All of these | |
| 205. |
The tertiary structure of yeast tRNA |
| A. | involves extensive base stacking interactions |
| B. | resembles the 3-dimensional structure of other tRNAs |
| C. | is maintained mostly by non-Watson-Crick base pairing |
| D. | all of the above |
| Answer» E. | |
| 206. |
The eukaryotic mRNA binding to the ribosomes is facilitated by |
| A. | T-RNA |
| B. | Poly-A tail |
| C. | Shine Dalgarno sequence |
| D. | 7-methyl guanosine cap |
| Answer» E. | |
| 207. |
Long 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» E. | |
| 208. |
The RNA primers used to initiate replication in E. coli |
| A. | result in Okazaki fragments on leading strand |
| B. | are removed by Pol I |
| C. | are joined together by DNA ligase |
| D. | are removed by helicase + ATP |
| Answer» C. are joined together by DNA ligase | |
| 209. |
Which of the following is true about RNA synthesis? |
| A. | Synthesis of RNA is always in the 5’ to 3’ direction |
| B. | RNA polymerase requires a primer for initiating transcription |
| C. | U is inserted opposite T in transcription |
| D. | New nucleotides are added on the 2’-OH of the ribose sugar |
| Answer» B. RNA polymerase requires a primer for initiating transcription | |
| 210. |
The size of a linear DNA fragment in a gel can be estimated by |
| A. | fluorescence in UV light |
| B. | the sedimentation coefficient |
| C. | the time it takes the gel to run |
| D. | comparison with a molecular weight standard such as Hind III digested phage lambda |
| Answer» E. | |
| 211. |
The anticodon of tRNA |
| A. | binds to rRNA |
| B. | binds to an amino acid |
| C. | binds to the Shine Dalgarno sequence |
| D. | binds to an mRNA codon |
| Answer» E. | |
| 212. |
Number of hydrogen bonds that form between U and A in a Watson-Crick base pair interactions? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» D. 3 | |
| 213. |
The ribosomes are composed of |
| A. | proteins |
| B. | RNA |
| C. | both (a) and (b) |
| D. | lipids |
| Answer» D. lipids | |
| 214. |
DNA segments capable of moving from one place in the genome to another is known as |
| A. | transposons |
| B. | retrovirus |
| C. | introns |
| D. | moving elements |
| Answer» B. retrovirus | |
| 215. |
Degenerated codon differs mostly in |
| A. | the identities of their second base |
| B. | the identities of their third base |
| C. | the wobble position |
| D. | both (b) and (c) |
| Answer» E. | |
| 216. |
Which of the following are essential to the condensation of chromosomes as cells enter mitosis? |
| A. | Cohesins |
| B. | Condensins |
| C. | Histones |
| D. | Topoisomerases |
| Answer» C. Histones | |
| 217. |
Transcription is catalyzed by |
| A. | DNA-dependent RNA polymerases |
| B. | RNA-dependent DNA polymerases |
| C. | Reverse transcriptases |
| D. | DNA ligases |
| Answer» B. RNA-dependent DNA polymerases | |
| 218. |
The anticodon is a structure on |
| A. | mRNA. |
| B. | tRNA. |
| C. | aribosome. |
| D. | rRNA. |
| Answer» C. aribosome. | |
| 219. |
Which position of a codon is said to wobble? |
| A. | First |
| B. | Second |
| C. | Third |
| D. | Fourth |
| Answer» D. Fourth | |
| 220. |
Where does RNA polymerase bind DNA? |
| A. | Promoter |
| B. | Operator |
| C. | Enhancer |
| D. | None of the mentioned |
| Answer» B. Operator | |
| 221. |
The initiation codon is |
| A. | AUG |
| B. | UAA |
| C. | UAG |
| D. | UGA |
| Answer» B. UAA | |
| 222. |
Which of the following enzymes remove supercoiling in replicating DNA ahead of the replication fork? |
| A. | DNA polymerases |
| B. | Helicases |
| C. | Primases |
| D. | Topoisomerases |
| Answer» E. | |
| 223. |
Which of the following has the self-repairing mechanisms? |
| A. | DNA and RNA |
| B. | DNA, RNA and protein |
| C. | Only DNA |
| D. | DNA and proteins |
| Answer» D. DNA and proteins | |
| 224. |
Which of the following blocks the peptidyl transferase of 80S eukaryotic ribosomes? |
| A. | Chloramphenicol |
| B. | Cycloheximide |
| C. | Diphtheria toxin |
| D. | Ricin |
| Answer» C. Diphtheria toxin | |
| 225. |
Which of the following process occurs in regions where no large –scale sequence similarity is apparent? |
| A. | Homologous genetic recombination |
| B. | Site specific recombination |
| C. | Non-homologous recombination |
| D. | Replicative recombination |
| Answer» D. Replicative recombination | |
| 226. |
In which of the following cases the first base of anticodon pairs with two codons? |
| A. | When the first base of anticodon is A or C |
| B. | When the first base of anticodon is A or G |
| C. | When the first base of anticodon is inosine |
| D. | When the first base of anticodon is G or U |
| Answer» E. | |
| 227. |
A codon contains how many nucleotides |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 228. |
Actinomycin D is an inhibitor of |
| A. | Transcription |
| B. | Translation |
| C. | Replication |
| D. | None of the mentioned |
| Answer» B. Translation | |
| 229. |
The first step in translation is |
| A. | binding of the two ribosomal subunits to each other |
| B. | binding of mRNA to the two ribosomal subunits |
| C. | binding of tRNA to the small ribosomal subunit |
| D. | binding of mRNA to the small ribosomal subunit |
| Answer» E. | |
| 230. |
What is the IUPAC code for an A, C, T ambiguity in a nucleic acid sequence? |
| A. | B |
| B. | H |
| C. | S |
| D. | None of these |
| Answer» C. S | |
| 231. |
Type I proteins (plasma membrane) have a |
| A. | cleavage N- terminal signal sequence and a hydrophobic stop transfer sequence |
| B. | cleavaged N- terminal signal sequence that doubles as the membrane anchoring sequence |
| C. | multiple signal sequence and a hydrophobic stop transfer sequence |
| D. | multiple signal sequence that doubles as the membrane anchoring sequence |
| Answer» B. cleavaged N- terminal signal sequence that doubles as the membrane anchoring sequence | |
| 232. |
What is the approximate percentage of repetitive DNA sequences in human DNA? |
| A. | 10 to 20% |
| B. | 20 to 30% |
| C. | 30 to 40% |
| D. | 40 to 50% |
| Answer» C. 30 to 40% | |
| 233. |
For the DNA replication in eukaryotes, the cell cycle consists of |
| A. | G1, G2 and M phases |
| B. | S, G2 and M phases |
| C. | G1,S, G2 and M phases |
| D. | G2 and M phases |
| Answer» D. G2 and M phases | |
| 234. |
Which of the following is used to determine the appropriate stringency (Wallace rule)? |
| A. | Tm = 2 x (No.of G:C base pair) + 4 x (No.of A:T base pair) |
| B. | Tm = 4 x (No.of A:T base pair) + 2 x (No.of G:C base pair) |
| C. | Tm = 4 x (No.of G:C base pair) + 2 x (No.of A:T base pair) |
| D. | Tm = 69.3° + 0.41 (%)G+C -650/1 |
| Answer» D. Tm = 69.3° + 0.41 (%)G+C -650/1 | |
| 235. |
Number of times the two DNA strands are interwined in circular DNA and is known as |
| A. | helix frequency |
| B. | linking number |
| C. | twisting number |
| D. | none of these |
| Answer» C. twisting number | |
| 236. |
Overwinding or overtightening of DNA during replication is caused and removed by |
| A. | DNAb, DNA polymerase |
| B. | DNAa, gyrase |
| C. | DNAb, gyrase |
| D. | Single stranded protein, DNAa |
| Answer» D. Single stranded protein, DNAa | |
| 237. |
The enzyme of E.coli is a nuclease that initiates the repair of double stranded DNA breaks by homologous recombination |
| A. | DNA glycosylase |
| B. | DNA ligase |
| C. | DNA polymerase |
| D. | RNA polymerase |
| Answer» B. DNA ligase | |
| 238. |
Which of the following histones shows more sequence similarity among eukaryotic species? |
| A. | H1 |
| B. | H2A |
| C. | H2B |
| D. | H3 |
| Answer» E. | |
| 239. |
Which of the following is not a major class of chromatin proteins? |
| A. | Histones |
| B. | Topoisomerases |
| C. | SMC proteins |
| D. | Cohesins |
| Answer» E. | |
| 240. |
Role of sigma factor in bacterial RNA polymerase is |
| A. | Catalyzing RNA synthesis |
| B. | Positioning RNA polymerase correctly on the DNA template |
| C. | Terminating RNA synthesis |
| D. | Unwinding DNA template |
| Answer» C. Terminating RNA synthesis | |
| 241. |
The enzyme used in the formation of cDNA from mRNA is |
| A. | Polymerase |
| B. | Helicase |
| C. | Reverse transcriptase |
| D. | Gyrase |
| Answer» D. Gyrase | |
| 242. |
DNA replication is |
| A. | Conservative |
| B. | Non-conservative |
| C. | Semi-conservative |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 243. |
The role of primase is to |
| A. | dismantle RNA primer |
| B. | cleave and unwinds short sections of DNA ahead of the replication fork |
| C. | proofread base pairing |
| D. | synthesize an RNA primer to begin the elongation process |
| Answer» E. | |
| 244. |
Which of the following does not code for an enzyme having both helicase and nuclease activity? |
| A. | Rec-A |
| B. | Rec-B |
| C. | Rec-C |
| D. | Rec-D |
| Answer» B. Rec-B | |
| 245. |
Deoxyribonucleoside triphosphates, being need in the chain termination methods are |
| A. | dATP |
| B. | dGTP and dCTP |
| C. | dTTP |
| D. | all of these |
| Answer» E. | |
| 246. |
In DNA replication, one new strand is synthesized complementary to an old (parent) strand and is referred as |
| A. | mutational |
| B. | semiconservative |
| C. | discontinuous |
| D. | antiparallel |
| Answer» C. discontinuous | |
| 247. |
Each replication bubbles consists of |
| A. | 3 replication forks |
| B. | 2 replication forks |
| C. | 4 replication forks |
| D. | 1 replication forks |
| Answer» C. 4 replication forks | |
| 248. |
In a cesium chloride gradient, DNA labeled with 15N and centrifuged will form a band |
| A. | above DNA containing 14N |
| B. | below DNA containing 14N |
| C. | with 14N-containing DNA |
| D. | all of these |
| Answer» C. with 14N-containing DNA | |
| 249. |
Signal sequences are |
| A. | Short peptide sequences attached to a protein that initiates its degradation by digestive enzymes |
| B. | Short peptide sequences to transport a protein to the nucleus |
| C. | Glycoproteins that serve as an address for transporting newly synthesized protein to the correct location |
| D. | Short peptide sequences that serves as an address for transporting newly synthesized proteins to the correct location |
| Answer» E. | |
| 250. |
Proteins tagged with mannose 6-phosphate are transported to |
| A. | Golgi complex |
| B. | Mitochondria |
| C. | Lysosome |
| D. | Nucleus |
| Answer» D. Nucleus | |