MCQOPTIONS
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MCQOPTIONS
This section includes 20 Mcqs, each offering curated multiple-choice questions to sharpen your Microbiology knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which of the following mutation affects only a single nucleotide? |
| A. | Aerial mutation |
| B. | Site mutation |
| C. | Point mutation |
| D. | Regional mutation |
| Answer» D. Regional mutation | |
| 2. |
When mutations involve vital functions so that the mutants are nonviable, it is a |
| A. | nonsense mutation |
| B. | lethal mutation |
| C. | transversion |
| D. | none of these |
| Answer» C. transversion | |
| 3. |
A mutagen is defined as |
| A. | an enzyme that repairs mutations |
| B. | a chemical or physical agent that induces mutations |
| C. | an inhibitor of gene modification |
| D. | a molecule which stabilizes DNA thus prevents mutations from occurring |
| Answer» C. an inhibitor of gene modification | |
| 4. |
The DNA sequences of rRNA genes can be used to |
| A. | assess relatedness of eukaryotes but not prokaryotes |
| B. | obtain a tentative identification of a new microorganism |
| C. | predict the pulsed field gel pattern of a microorganism |
| D. | predict whether a bacteria will be gram-positive or gram-negative |
| Answer» C. predict the pulsed field gel pattern of a microorganism | |
| 5. |
A nonsense mutation introduced into the DNA sequence of a gene may |
| A. | cause premature termination of the mRNA |
| B. | shorten the length of the protein encoded by the gene |
| C. | have no effect on the transcript or protein made |
| D. | cause a shift in reading frame |
| Answer» C. have no effect on the transcript or protein made | |
| 6. |
What was the first eukaryotic chromosome to be sequenced? |
| A. | Yeast chromosome III |
| B. | Yeast chromosome XI |
| C. | Arabidopsis chromosome IV |
| D. | None of these |
| Answer» B. Yeast chromosome XI | |
| 7. |
Which of the following mutations arise without exposure to external agents? |
| A. | Spontaneous mutations |
| B. | Analogous mutations |
| C. | Induced mutations |
| D. | None of these |
| Answer» B. Analogous mutations | |
| 8. |
Due to which of the following DNA repair mechanisms, one is able to distinguish newly synthesized DNA strands from older one? |
| A. | New strands do not contain cytosine bases |
| B. | New strands are lower in molecular size |
| C. | Old strands are methylated while new strands are not |
| D. | New strands are methylated while old strands are not |
| Answer» D. New strands are methylated while old strands are not | |
| 9. |
Which of the following bacterial genome was sequenced first? |
| A. | <i>E. coli</i> |
| B. | <i>S. pneumoniae</i> |
| C. | <i>H. influenzae</i> |
| D. | <i>S. thermophilus</i> |
| Answer» D. <i>S. thermophilus</i> | |
| 10. |
A nonsense mutation may result into |
| A. | an abnormal elongation of a polypeptide |
| B. | a large deletion within the reading frame of a gene |
| C. | a premature termination of the synthesis of a polypeptide |
| D. | modification of mRNA |
| Answer» D. modification of mRNA | |
| 11. |
Which of these mechanisms for thymine dimers repair lead to mutations? |
| A. | Excision repair |
| B. | Photoreactivation |
| C. | SOS repair |
| D. | Never leads to mutation |
| Answer» D. Never leads to mutation | |
| 12. |
Frame shift mutation may occur as a result of |
| A. | formation of a thymine-dimer |
| B. | deamination of cytosine to uracil |
| C. | conversion of guanine to xanthine |
| D. | none of the above |
| Answer» E. | |
| 13. |
Thymine dimers are directly repaired with the help of visible light by process known as |
| A. | phosphorylation |
| B. | excision repair |
| C. | photosynthesis |
| D. | photoreactivation |
| Answer» E. | |
| 14. |
Differentiation of four different bases in automated sequencing systems is that each base has |
| A. | different radioactive tag |
| B. | cytosine at start |
| C. | unique antibody bound to it |
| D. | distinctive fluorescent tag |
| Answer» E. | |
| 15. |
Changes in which of the following characterizes mutations? |
| A. | Phenotype |
| B. | Genotype |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» D. None of these | |
| 16. |
Which of the following(s) is/are steps in excision repair mechanisms? |
| A. | Excision |
| B. | Incision |
| C. | Ligation |
| D. | All of these |
| Answer» E. | |
| 17. |
The whole-genome shotgun sequencing approach depends primarily on |
| A. | rapidly sequencing thousands of small randomly cloned fragments |
| B. | methodical sequencing a few large cloned fragments of DNA |
| C. | sequencing the bacterial chromosome while it is still intact |
| D. | all of the above |
| Answer» B. methodical sequencing a few large cloned fragments of DNA | |
| 18. |
Genetic variations are |
| A. | temporary |
| B. | influenced by the environment |
| C. | stable |
| D. | not heritable |
| Answer» D. not heritable | |
| 19. |
The mutation which will not affect the length of a protein is, |
| A. | nonsense mutation |
| B. | missense mutation |
| C. | frameshift mutation |
| D. | all of these |
| Answer» C. frameshift mutation | |
| 20. |
The promoter on an expression vector used to overproduce proteins in bacteria is |
| A. | a bacterial promoter |
| B. | expressed both in bacteria and mammalian cells |
| C. | not a regulated promoter |
| D. | the natural promoter of the gene being cloned |
| Answer» B. expressed both in bacteria and mammalian cells | |