MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 94 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
An FT-IR instrument record a signal in the |
| A. | time domain |
| B. | frequency domain |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» B. frequency domain | |
| 2. |
What is meant by rotating frame of reference? |
| A. | That the sample is spun rapidly in the applied field |
| B. | If the laboratory itself is imagined to be rotated at the Larmor frequency, viewing that individual magnetic moment vectors are fixed in space |
| C. | That the detector rotates around the sample |
| D. | None of the above |
| Answer» C. That the detector rotates around the sample | |
| 3. |
Which of these effects result from slow injection of a large sample volume? |
| A. | Increased resolution |
| B. | Decreased resolution |
| C. | Non-linear detector response |
| D. | Constant resolution |
| Answer» C. Non-linear detector response | |
| 4. |
Which of the following detectors give concentration-dependent signals? |
| A. | Electron-capture detector |
| B. | Thermal conductivity |
| C. | Infra-red detector |
| D. | All of these |
| Answer» E. | |
| 5. |
In scanning electron microscopy |
| A. | a specimen is fixed and then coated with thin layer of a heavy metal |
| B. | a specimen is fixed and then coated with transition metal |
| C. | a specimen is not fixed and then coated with thin layer of a heavy metal |
| D. | none of the above |
| Answer» B. a specimen is fixed and then coated with transition metal | |
| 6. |
How do you turn a signal recorded in the time domain into a frequency domain signal? |
| A. | Fourier transformation |
| B. | Measurement of peak areas |
| C. | By use of a Michelson interferometer |
| D. | None of the above |
| Answer» B. Measurement of peak areas | |
| 7. |
Which of the following are not used as stationary phases in a GC column? |
| A. | Polysiloxanes |
| B. | Silica |
| C. | Cyclodextrins |
| D. | None are used as stationary phases |
| Answer» C. Cyclodextrins | |
| 8. |
A retention gap is placed between the injector and the front of the column to |
| A. | retain contaminants and prevent them from reaching the column |
| B. | retain the sample and release it gradually to the column |
| C. | prevent backflush of the injected solution |
| D. | all of the above |
| Answer» B. retain the sample and release it gradually to the column | |
| 9. |
When radiation energy is absorbed by a spin 1/2 nucleus in a magnetic field, what happens? |
| A. | The processional frequency of the nucleus increases |
| B. | The nucleus spins faster |
| C. | The angle of precession flips so that the magnetic moment of the nucleus opposes the applied field |
| D. | none of the above |
| Answer» D. none of the above | |
| 10. |
Which of the following is the basis of first dimension of separation for two-dimensional electrophoresis? |
| A. | Molecular mass |
| B. | Solubility |
| C. | Isoelectric point |
| D. | Folding |
| Answer» D. Folding | |
| 11. |
Column bleeding occurs when |
| A. | elution of the analyte is extended over time |
| B. | the column is cracked and stationary phase leaks out |
| C. | traces of the stationary phase are eluted |
| D. | the column breaks during installation and causes personal injury |
| Answer» D. the column breaks during installation and causes personal injury | |
| 12. |
Resolution is proportional to the |
| A. | number of theoretical plates in a column |
| B. | square root of the number of theoretical plates in a column |
| C. | square of the number of theoretical plates in a column |
| D. | cube root of the number of theoretical plates in a column |
| Answer» C. square of the number of theoretical plates in a column | |
| 13. |
Doubling the column's length increases resolution by a factor of |
| A. | (2)^0.5 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» B. 2 | |
| 14. |
Theoretical plates are used to |
| A. | estimate the efficiency of a column |
| B. | determine the thickness of the stationary phase |
| C. | measure the distribution of the analyte between mobile and stationary phases |
| D. | None of the above |
| Answer» B. determine the thickness of the stationary phase | |
| 15. |
Which of the following is not used for detection in GC? |
| A. | Infrared spectroscopy |
| B. | NMR |
| C. | Flame ionisation |
| D. | Electrical conductivity |
| Answer» C. Flame ionisation | |
| 16. |
In FT-NMR, how are nuclei excited? |
| A. | By radio-frequency radiation whose frequency is swept across a predetermined range |
| B. | By an intense pulse of radiation which contains a wide range of frequencies |
| C. | By an intense pressure |
| D. | None of the above |
| Answer» B. By an intense pulse of radiation which contains a wide range of frequencies | |
| 17. |
Sample retention in the column is measured by |
| A. | retention time |
| B. | retention factor |
| C. | retention index |
| D. | all of these |
| Answer» E. | |
| 18. |
In immunofluroscence microscopy, fluroscent compounds are attached to |
| A. | an antibody specific for the subcellular structure |
| B. | an antigen specific for the subcellular structure |
| C. | bound antibody specific for the subcellular structure |
| D. | none of these |
| Answer» B. an antigen specific for the subcellular structure | |
| 19. |
Sample injection is considered successful if |
| A. | all of the sample in the injector has been added to the column |
| B. | the sample is concentrated at the start of the column |
| C. | the sample is spread evenly along the column |
| D. | the sample is homogenously spread along the column |
| Answer» C. the sample is spread evenly along the column | |
| 20. |
What is the name given to the relaxation process due to an interaction between an excited nucleus and the magnetic fields caused by nuclei in molecules moving around in the sample? |
| A. | Spin - lattice relaxation |
| B. | Spin - spin relaxation |
| C. | Spin - spin - spin relaxation |
| D. | None of these |
| Answer» B. Spin - spin relaxation | |
| 21. |
Negative staining is a technique used in |
| A. | electron microscopy |
| B. | gel electrophoresis |
| C. | immunocytochemistry |
| D. | light microscopy |
| Answer» B. gel electrophoresis | |
| 22. |
Helium is generally preferred as carrier gas over nitrogen and hydrogen because |
| A. | it is inert |
| B. | it has a lower viscosity |
| C. | it doubles up as a party gas for balloons and funny voices |
| D. | all of above |
| Answer» E. | |
| 23. |
In column switching chromatography |
| A. | compounds trapped on one column are eluted to another column |
| B. | one column is removed and replaced by another |
| C. | the flow to the column is switched on and off repeatedly |
| D. | any of the above |
| Answer» B. one column is removed and replaced by another | |
| 24. |
Cytochrome C has an isoelectric pH of |
| A. | 8.5 |
| B. | 10.05 |
| C. | 7.5 |
| D. | 11.05 |
| Answer» C. 7.5 | |
| 25. |
Why is it advantageous to record many FID signals from the same sample and then add them together? |
| A. | To ensure that all target nuclei in the sample have been excited |
| B. | To remove inaccuracies caused by fluctuations in the applied magnetic field |
| C. | To increase sensitivity |
| D. | None of the above |
| Answer» D. None of the above | |
| 26. |
The frequency of precession, the transition frequency and the Larmor frequency are |
| A. | different terms for the same frequency |
| B. | same terms for the same frequency |
| C. | different terms for the different frequency |
| D. | same terms for the different frequency |
| Answer» B. same terms for the same frequency | |
| 27. |
What are the benefits of decreasing the column internal diameter? |
| A. | Increased sample capacity |
| B. | Increased resolution |
| C. | Reduced risk of column overloading |
| D. | All of the above |
| Answer» C. Reduced risk of column overloading | |
| 28. |
Where does a carbonyl (C=0) stretch appear in an IR spectrum? |
| A. | 1740-1720 |
| B. | 1870-1650 |
| C. | 3640-3250 |
| D. | 160-110 |
| Answer» C. 3640-3250 | |
| 29. |
What useful information can be found from a Van Deemter plot? |
| A. | The selectivity factor |
| B. | Optimum mobile phase flow rate |
| C. | Optimum column temperature |
| D. | Optimum column length |
| Answer» C. Optimum column temperature | |
| 30. |
What is the typical internal diameter of fused silica capillary columns? |
| A. | 0.2-0.3 mm |
| B. | 0.3-0.5mm |
| C. | 0.5-1.0 mm |
| D. | 1.0-2.0 mm |
| Answer» B. 0.3-0.5mm | |
| 31. |
In the intersystem crossing |
| A. | the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa) |
| B. | a molecule converts its excess energy to light, and emits a photon |
| C. | a molecule converts excess electronic energy to vibrational energy |
| D. | all of the above |
| Answer» B. a molecule converts its excess energy to light, and emits a photon | |
| 32. |
Why must the radiation source for fluorescence spectrometry be more powerful than for absorption spectroscopy? |
| A. | Because the magnitude of the output signal is proportional to the power of the incident radiation |
| B. | Because the sample won't fluoresce if the incident radiation is of low power |
| C. | To allow for scattering by the sample |
| D. | None of the above |
| Answer» B. Because the sample won't fluoresce if the incident radiation is of low power | |
| 33. |
Why do fluorescence spectrometers often use double-beam optics? |
| A. | So a reference solution can be used |
| B. | To compensate for beam attenuation by the monochromator |
| C. | To compensate for power fluctuations in the radiation source |
| D. | All of the above |
| Answer» D. All of the above | |
| 34. |
For a molecule to absorb IR, why must the molecule's vibrations cause fluctuations in the dipole moment of the molecule? |
| A. | Because a change in dipole moment lowers the energy required for electronic transitions |
| B. | Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment |
| C. | Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching |
| D. | All of the above |
| Answer» C. Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching | |
| 35. |
Internal conversion is where |
| A. | the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa) |
| B. | A molecule converts its excess energy to light, and emits a photon |
| C. | A molecule converts excess electronic energy to vibrational energy |
| D. | none of the above |
| Answer» D. none of the above | |
| 36. |
Fluorescence occurs when |
| A. | a molecule returns to the electronic ground state from an excited triplet state by losing it's excess energy as a photon |
| B. | a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon |
| C. | a molecule lowers its vibrational energy by losing it's excess energy as a photon |
| D. | none of the above |
| Answer» C. a molecule lowers its vibrational energy by losing it's excess energy as a photon | |
| 37. |
Why phosphorescence measurements are usually made at a low temperature? |
| A. | To prevent thermal degradation of the phosphorescent species |
| B. | To promote phosphorescence by slowing the rate of radiationless transfer processes |
| C. | To increase the efficiency of the detector |
| D. | To decease the efficiency of detector |
| Answer» C. To increase the efficiency of the detector | |
| 38. |
Thin layer chromatography is |
| A. | partition chromatography |
| B. | electrical mobility of ionic species |
| C. | adsorption chromatography |
| D. | none of the above |
| Answer» D. none of the above | |
| 39. |
Which of the following will oscillate the fastest? |
| A. | A large mass on a weak spring |
| B. | A large mass on a stiff spring |
| C. | A small mass on a stiff spring |
| D. | A small mass on a weak spring |
| Answer» D. A small mass on a weak spring | |
| 40. |
In the equation, A = ε bc, what quantity is represented by "ε"? |
| A. | Absorbtivity |
| B. | Molar absorbtivity |
| C. | Path length |
| D. | None of these |
| Answer» C. Path length | |
| 41. |
Why must the voltage supplied to a tungsten lamp be very stable? |
| A. | Because if it wasn't, the lamp would bum out |
| B. | Because amount of energy the lamp emits is proportional to the fourth power of the operating voltage |
| C. | Because the lamp will only function at a specific voltage |
| D. | All of the above |
| Answer» C. Because the lamp will only function at a specific voltage | |
| 42. |
In the past, IR spectra had to be aquired one wavelength at a time, which took a long time. Today quick spectra is due to the |
| A. | the Fourier Transfer Algorithm allows us to scan all frequencies at once |
| B. | light is faster today that it used to be |
| C. | absence of broad spectrum of wavelenth |
| D. | none of the above |
| Answer» B. light is faster today that it used to be | |
| 43. |
Which of the following relationships between absorbance and %transmittance is incorrect? |
| A. | A = log10 100 / %T |
| B. | A = 2 - log10 %T |
| C. | A = log10 1 / T |
| D. | All are correct |
| Answer» D. All are correct | |
| 44. |
Which of the following is not an IR vibrational mode? |
| A. | Stretching |
| B. | Scissoring |
| C. | Rocking |
| D. | Rolling |
| Answer» E. | |
| 45. |
Dwell volume is defined as |
| A. | the volume of solvent contained in a liquid chromatographic column |
| B. | the time required for the gradient to reach the column |
| C. | the volume of the column between the point at which solvents are mixed and the beginning of the column |
| D. | none of these |
| Answer» D. none of these | |
| 46. |
Void volume refers to the |
| A. | total volume of eluent in the column the remainder being taken up by the packing material |
| B. | the volume of solvent contained in a liquid chromatographic column |
| C. | the time required for the gradient to reach the column |
| D. | the volume of the column between the point at which solvents are mixed and the beginning of the column |
| Answer» B. the volume of solvent contained in a liquid chromatographic column | |
| 47. |
In normal phase HPLC, there is a |
| A. | non polar solvent/polar column |
| B. | polar solvent/non-polar column |
| C. | non polar solvent/non-polar column |
| D. | any of the above |
| Answer» B. polar solvent/non-polar column | |
| 48. |
Which can be used as a mobile phase in HPLC applications? |
| A. | Any compound with solubility in liquid |
| B. | Any compound with limited solubility in liquid |
| C. | Any compound with non-solubility in liquid |
| D. | Any of the above |
| Answer» B. Any compound with limited solubility in liquid | |
| 49. |
Beer's Law states that |
| A. | absorbance is proportional to both the path length and concentration of the absorbing species |
| B. | absorbance is proportional to the log of the concentration of the absorbing species |
| C. | absorbance is equal to P0 / P |
| D. | none of the above |
| Answer» B. absorbance is proportional to the log of the concentration of the absorbing species | |
| 50. |
Molar absorbtivities of compounds exhibiting charge transfer absorption are |
| A. | small |
| B. | moderate |
| C. | large |
| D. | none of these |
| Answer» D. none of these | |