Biochemistry MCQ Quiz Hub

1. Molar absorbtivity is the measure of the
amount of light absorbed per unit length
amount of light absorbed per unit concentration
amount of light reflected and absorbed per unit concentration
None of the above

2. Which of the following relationships between absorbance and %transmittance is incorrect?
A = log10 100 / %T
A = 2 - log10 %T
A = log10 1 / T
All are correct

3. Why is it generally preferable to use absorbance as a measure of absorption rather than % transmittance?
Because %T cannot be measured as accurately as absorbance
Because %T is dependant on the power of the incident radiation
Because absorbance is proportional to the concentration of the analyte, whereas %T is not
none of the above

4. 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
the Fourier Transfer Algorithm allows us to scan all frequencies at once
light is faster today that it used to be
absence of broad spectrum of wavelenth
none of the above

5. Which of the following is not an IR vibrational mode?
Stretching
Scissoring
Rocking
Rolling

6. Which of the following will oscillate the fastest?
A large mass on a weak spring
A large mass on a stiff spring
A small mass on a stiff spring
A small mass on a weak spring

7. n the equation, A = ε bc, what quantity is represented by "ε"?
Absorbtivity
Molar absorbtivity
Path length
None of these

8. Why must the voltage supplied to a tungsten lamp be very stable?
Because if it wasn't, the lamp would bum out
Because amount of energy the lamp emits is proportional to the fourth power of the operating voltage
Because the lamp will only function at a specific voltage
All of the above

9. Where does a carbonyl (C=0) stretch appear in an IR spectrum?
1740-1720
1870-1650
3640-3250
160-110

10. Which of the following components of a monochromator is the dispersing element?
The collimating lens
The entrance slit
The diffraction grating
None of these

11. A simple harmonic oscillator may absorb energy
at anytime.
when the frequencies match exactly
when the amplitudes are the same.
at no time.

12. UV-Vis spectroscopy of organic compounds is usually concerned with which electronic transition(s)?
σ → σ*
n → σ*
n → π* and π → π*
none of these

13. Vibrational spectroscopy is
a large mass on a weak spring
a flashlight through a prism and shake it
a class of spectroscopic techniques which analyzes molecular motions
an Infrared spectroscopy

14. Why are rotational transitions of little use to a spectroscopist?
Because the energy required to induce a rotational transition is so small that it cannot be measured
Because rotational transitions are extremely rare
Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
All of the above

15. Why are rotational transitions of little use to a spectroscopist?
Because the energy required to induce a rotational transition is so small that it cannot be measured
Because rotational transitions are extremely rare
Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
All of the above

16. 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

17. What is the relationship between wavelength and wave number?
Wavenumber = 1 / wavelength in centimeters
Wavenumber - wavelength in nanometers = 1
Wavelength in nanometers x wavenumber = 1
None of the above

18. In the intersystem crossing
the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
a molecule converts its excess energy to light, and emits a photon
a molecule converts excess electronic energy to vibrational energy
all of the above

19. Why must the radiation source for fluorescence spectrometry be more powerful than for absorption spectroscopy?
Because the magnitude of the output signal is proportional to the power of the incident radiation
Because the sample won't fluoresce if the incident radiation is of low power
To allow for scattering by the sample
None of the above

20. Why do fluorescence spectrometers often use double-beam optics?
So a reference solution can be used
To compensate for beam attenuation by the monochromator
To compensate for power fluctuations in the radiation source
All of the above

21. For a molecule to absorb IR, why must the molecule's vibrations cause fluctuations in the dipole moment of the molecule?
Because a change in dipole moment lowers the energy required for electronic transitions
Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment
Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching
All of the above

22. nternal conversion is where
the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
A molecule converts its excess energy to light, and emits a photon
A molecule converts excess electronic energy to vibrational energy
none of the above

23. Why phosphorescence measurements are usually made at a low temperature?
To prevent thermal degradation of the phosphorescent species
To promote phosphorescence by slowing the rate of radiationless transfer processes
To increase the efficiency of the detector
To decease the efficiency of detector

24. Fluorescence occurs when
a molecule returns to the electronic ground state from an excited triplet state by losing it's excess energy as a photon
a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon
a molecule lowers its vibrational energy by losing it's excess energy as a photon
none of the above

25. Thin layer chromatography is
partition chromatography
electrical mobility of ionic species
adsorption chromatography
none of the above

26. In gas chromatography, the basis for separation of the components of the volatile material is the difference in
partition coefficients
conductivity
molecular weight
molarity

27. In reverse phase chromatography, the stationary phase is made
non-polar
polar
either non-polar or polar
none of these

28. Ion exchange chromatography is based on the
electrostatic attraction
electrical mobility of ionic species
adsorption chromatography
partition chromatography

29. The general expression for the appearance of a solute in an effluent is (where V is the elution volume of a substance , V0 void volume, kD distribution constant and Vi internal water volume)
V = V0 + kDVi
V = V0/Vi
V = V0 - kDVi
V/V0 = kDVi

30. A combination of paper chromatography and electrophoresis involves
partition chromatography
electrical mobility of the ionic species
both (a) and (b)
none of these

31. HPLC stands for
High Pressure Liquid Chromatography
High Performance Liquid Chromatography
both (a) and (b)
Highly Placed Liquid Chromatography

32. The eluent strength is a measure of
solvent adsorption energy
solvent absorption energy
solvent diffusivity
solvent mixing index

33. HPLC methods include
liquid/liquid (partition) chromatography
liquid/solid (adsorption) chromatography
ion exchange and size exclusion chromatography
all of the above

34. Column efficiency is measured in terms of number of plates which is
inversely related to the square of the peak width
directly related to the square of the peak width
inversely related to the cube root of the peak width
directly related to the square of the peak width

35. For a typical adsorbent such as silica gel, the most popular pore diameters are
10 and 50 A°
60 and 100 A°
100 and 150 A°
150 and 200 A°

36. An isocratic elution in HPLC is one in which the composition of the solvent
remains constant
changes continuously
changes in a series of steps
none of these

37. n reversed phase HPLC, there is a
non polar solvent/polar column
polar solvent/non-polar column
non polar solvent/non-polar column
any of the above

38. Which of the following statements is true for a refractive index detector in HPLC?
It is more sensitive than a UV detector
It can only be used for isocratic elutions
It does not respond to many solutes
none of above

39. A gradient elution in HPLC is one in which the composition of the solvent
remains constant
is changed continuously or in a series of steps
both (a) and (b)
none of the above

40. An eluotropic series
ranks solvents by their relative abilities to displace solutes from a given absorbent
ranks column packing material by their relative abilities to retain solutes on the column
is a measure of the solvent adsorption energy
none of above

41. Dwell volume is defined as
the volume of solvent contained in a liquid chromatographic column
the time required for the gradient to reach the column
the volume of the column between the point at which solvents are mixed and the beginning of the column
none of these

42. Void volume refers to the
total volume of eluent in the column the remainder being taken up by the packing material
the volume of solvent contained in a liquid chromatographic column
the time required for the gradient to reach the column
the volume of the column between the point at which solvents are mixed and the beginning of the column

43. 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

44. Which of the following(s) is/are the advantage of HPLC over traditional LPLC (low-pressure liquid chromatography)?
Greater sensitivity and reusable column
Ideal for ionic species and large molecules
Sample recovery
All of the above

45. Which can be used as a mobile phase in HPLC applications?
Any compound with solubility in liquid
Any compound with limited solubility in liquid
Any compound with non-solubility in liquid
Any of the above

46. Which of the following two organelles look most alike structurally?
Nucleus and vesicle
Golgi apparatus and smooth endoplasmic reticulum ER
Vacuole and cytoskeleton
Lysosome and chloroplast

47. In terms of basic cell structure, what do an elephant and an oak tree have in common?
They both are eukaryotes
They both have a cell nucleus
They both have mitochondria
All of the above

48. Where in a eukaryotic cell, DNA can be found?
Nucleus
Mitochondrion
Vacuole
Both (a) and (b)

49. Which of the following structures is expected in a bacterium?
Nucleus
Plasma membrane
Golgi apparatus
Endoplasmic reticulum

50. Which of the following organelles is directly connected to the outer membrane of the nucleus in a eukaryotic cell?
Mitochondrion
Lysosome
Golgi apparatus
Endoplasmic reticulum

51. Microtubules, motor proteins, and actin filaments are all part of
the mechanism of photosynthesis that occurs in chloroplasts
the rough ER (endoplasmic reticulum) in prokaryotic cells
the cytoskeleton of eukaryotic cells
the process that moves small molecules across cell membranes

52. A certain cell organelle which is made of a double phospholipid bilayer that has many large pores in it, is most likely
the nuclear envelope
the plasma membrane
the mitochondrion
the cytoskeleton

53. Which of the following cell organelles are expected to be associated with motor proteins?
Smooth ER
Vesicles
Plasma membrane
Chloroplasts

54. Eukaryotic cells are more efficient than prokaryotes because their internal compartmentalization
makes each compartment nutritionally independent of all others
allows for specialization through the subdivision of particular tasks
allows for specialization through merging of different tasks
reduces overall cell size

55. An organism's first line of defense against attack by an invader such as a virus or bacterium is usually
to flee or hide
its body wall
a specific immune response
a nonspecific immune response

56. According to the fluid mosaic model of cell membranes,
the most common type of molecules in the membrane are proteins
basic membrane structure results from how the proteins interact with water
the membrane is a highly mobile mixture of phospholipids and proteins
the unique properties of cell types are determined by their phospholipids

57. The simplest way to differentiate a prokaryotic cell from a eukaryotic one is to
look for a plasma membrane
see if a nucleus is present
check for the presence of DNA
. determine if the cell is an entire organism or not

58. Which of the following is the best criterion for deciding whether a cell is prokaryotic or eukaryotic?
The cell came from a single-celled or multicelled organism
The cell has a nucleus or not
The cell has cytosol or not
DNA is present in the cell or not

59. Lysosomes are specialized vesicles in __________ that contain digestive enzymes for the breakdown of food. A related organalle known as a vacuole, which is found in __________ , also contains enzymes but in addition may act as a storage organelle for nutrients or water.
animals; plants and fungi
plants; animals and fungi
plants and fungi; animals
animals and plants; fungi

60. The highly folded membranes found in such eukaryotic organelles as mitochondria and chloroplasts
increase the surface area where key chemical processes can occur
help the cell against physical damage
make it possible to package large amounts of DNA within the cell
assist with cell movement

61. Which of the following statements about prokaryotes is false?
Prokaryotic cells concentrate important materials for the cells survival
The substance known as cytosol is found within the bacterial nucleus
Prokaryotic cells are much smaller than most eukaryotic cells
Ancient prokaryotes may have given rise to some eukaryotic organelles

62. What do dystrophin, utrophin, actin, and tubulin have to do with eukaryotic cell structure and function?
They are components in the reactions of photosynthesis
They all participate in the degradation of large amounts of ATP
They all participate in the production of large amounts of ATP
They are all embedded proteins in plasma membranes

63. In which of the following cell organelles, it is expected to find the biochemical reactions that harness energy from the breakdown of sugar molecules to synthesize large amounts of ATP?
Lysosome
Vesicles
Mitochondria
Plasma membrane

64. Which of the following macromolecules are found in the plasma membrane?
Lipids and proteins only
Lipids, proteins, and carbohydrates
Proteins and carbohydrates only
Proteins only

65. Clearly defined nucleus, mitochondria in a large central vacuole and chloroplasts, indicate the group of organisms from
bacteria
fungi
plants
animals

66. Which of the following are responsible causing the diseases?
Pathogens
T cells
Lymphocytes
Macrophages

67. In which of the following cell types more cellular detail can be observed using an electron microscope compared to a light microscope?
Animal
Bacterial
Protist
All of these

68. Which of the following is present in both prokaryotes and eukaryotes?
Lysosome
Chloroplast
Plasma membrane
Vacuole

69. Hydrogen bonds in a-helices are
more numerous than Vander Waals interactions
not present at Phe residues
analogous to the steps in a spiral staircase
roughly parallel to the helix axis

70. The peptide bond in proteins is
only found between proline residues
usually cis unless proline is the next amino acid
usually trans unless proline is the next amino acid
is planar because of steric hinderance