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Biochemistry MCQS PAPER SET 10
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Biochemistry MCQS PAPER SET 10
1
Molar absorbtivity is the measure of the
A
amount of light absorbed per unit length
B
amount of light absorbed per unit concentration
C
amount of light reflected and absorbed per unit concentration
D
None of the above
2
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
3
Why is it generally preferable to use absorbance as a measure of absorption rather than % transmittance?
A
Because %T cannot be measured as accurately as absorbance
B
Because %T is dependant on the power of the incident radiation
C
Because absorbance is proportional to the concentration of the analyte, whereas %T is not
D
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
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
5
Which of the following is not an IR vibrational mode?
A
Stretching
B
Scissoring
C
Rocking
D
Rolling
6
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
7
n the equation, A = ε bc, what quantity is represented by "ε"?
A
Absorbtivity
B
Molar absorbtivity
C
Path length
D
None of these
8
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
9
Where does a carbonyl (C=0) stretch appear in an IR spectrum?
A
1740-1720
B
1870-1650
C
3640-3250
D
160-110
10
Which of the following components of a monochromator is the dispersing element?
A
The collimating lens
B
The entrance slit
C
The diffraction grating
D
None of these
11
A simple harmonic oscillator may absorb energy
A
at anytime.
B
when the frequencies match exactly
C
when the amplitudes are the same.
D
at no time.
12
UV-Vis spectroscopy of organic compounds is usually concerned with which electronic transition(s)?
A
σ → σ*
B
n → σ*
C
n → π* and π → π*
D
none of these
13
Vibrational spectroscopy is
A
a large mass on a weak spring
B
a flashlight through a prism and shake it
C
a class of spectroscopic techniques which analyzes molecular motions
D
an Infrared spectroscopy
14
Why are rotational transitions of little use to a spectroscopist?
A
Because the energy required to induce a rotational transition is so small that it cannot be measured
B
Because rotational transitions are extremely rare
C
Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
D
All of the above
15
Why are rotational transitions of little use to a spectroscopist?
A
Because the energy required to induce a rotational transition is so small that it cannot be measured
B
Because rotational transitions are extremely rare
C
Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
D
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
A
B
C
D
17
What is the relationship between wavelength and wave number?
A
Wavenumber = 1 / wavelength in centimeters
B
Wavenumber - wavelength in nanometers = 1
C
Wavelength in nanometers x wavenumber = 1
D
None of the above
18
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
19
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
20
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
21
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
22
nternal 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
23
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
24
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
25
Thin layer chromatography is
A
partition chromatography
B
electrical mobility of ionic species
C
adsorption chromatography
D
none of the above
26
In gas chromatography, the basis for separation of the components of the volatile material is the difference in
A
partition coefficients
B
conductivity
C
molecular weight
D
molarity
27
In reverse phase chromatography, the stationary phase is made
A
non-polar
B
polar
C
either non-polar or polar
D
none of these
28
Ion exchange chromatography is based on the
A
electrostatic attraction
B
electrical mobility of ionic species
C
adsorption chromatography
D
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)
A
V = V0 + kDVi
B
V = V0/Vi
C
V = V0 - kDVi
D
V/V0 = kDVi
30
A combination of paper chromatography and electrophoresis involves
A
partition chromatography
B
electrical mobility of the ionic species
C
both (a) and (b)
D
none of these
31
HPLC stands for
A
High Pressure Liquid Chromatography
B
High Performance Liquid Chromatography
C
both (a) and (b)
D
Highly Placed Liquid Chromatography
32
The eluent strength is a measure of
A
solvent adsorption energy
B
solvent absorption energy
C
solvent diffusivity
D
solvent mixing index
33
HPLC methods include
A
liquid/liquid (partition) chromatography
B
liquid/solid (adsorption) chromatography
C
ion exchange and size exclusion chromatography
D
all of the above
34
Column efficiency is measured in terms of number of plates which is
A
inversely related to the square of the peak width
B
directly related to the square of the peak width
C
inversely related to the cube root of the peak width
D
directly related to the square of the peak width
35
For a typical adsorbent such as silica gel, the most popular pore diameters are
A
10 and 50 A°
B
60 and 100 A°
C
100 and 150 A°
D
150 and 200 A°
36
An isocratic elution in HPLC is one in which the composition of the solvent
A
remains constant
B
changes continuously
C
changes in a series of steps
D
none of these
37
n reversed 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
38
Which of the following statements is true for a refractive index detector in HPLC?
A
It is more sensitive than a UV detector
B
It can only be used for isocratic elutions
C
It does not respond to many solutes
D
none of above
39
A gradient elution in HPLC is one in which the composition of the solvent
A
remains constant
B
is changed continuously or in a series of steps
C
both (a) and (b)
D
none of the above
40
An eluotropic series
A
ranks solvents by their relative abilities to displace solutes from a given absorbent
B
ranks column packing material by their relative abilities to retain solutes on the column
C
is a measure of the solvent adsorption energy
D
none of above
41
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
42
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
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
A
B
C
D
44
Which of the following(s) is/are the advantage of HPLC over traditional LPLC (low-pressure liquid chromatography)?
A
Greater sensitivity and reusable column
B
Ideal for ionic species and large molecules
C
Sample recovery
D
All of the above
45
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
46
Which of the following two organelles look most alike structurally?
A
Nucleus and vesicle
B
Golgi apparatus and smooth endoplasmic reticulum ER
C
Vacuole and cytoskeleton
D
Lysosome and chloroplast
47
In terms of basic cell structure, what do an elephant and an oak tree have in common?
A
They both are eukaryotes
B
They both have a cell nucleus
C
They both have mitochondria
D
All of the above
48
Where in a eukaryotic cell, DNA can be found?
A
Nucleus
B
Mitochondrion
C
Vacuole
D
Both (a) and (b)
49
Which of the following structures is expected in a bacterium?
A
Nucleus
B
Plasma membrane
C
Golgi apparatus
D
Endoplasmic reticulum
50
Which of the following organelles is directly connected to the outer membrane of the nucleus in a eukaryotic cell?
A
Mitochondrion
B
Lysosome
C
Golgi apparatus
D
Endoplasmic reticulum
51
Microtubules, motor proteins, and actin filaments are all part of
A
the mechanism of photosynthesis that occurs in chloroplasts
B
the rough ER (endoplasmic reticulum) in prokaryotic cells
C
the cytoskeleton of eukaryotic cells
D
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
A
the nuclear envelope
B
the plasma membrane
C
the mitochondrion
D
the cytoskeleton
53
Which of the following cell organelles are expected to be associated with motor proteins?
A
Smooth ER
B
Vesicles
C
Plasma membrane
D
Chloroplasts
54
Eukaryotic cells are more efficient than prokaryotes because their internal compartmentalization
A
makes each compartment nutritionally independent of all others
B
allows for specialization through the subdivision of particular tasks
C
allows for specialization through merging of different tasks
D
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
A
to flee or hide
B
its body wall
C
a specific immune response
D
a nonspecific immune response
56
According to the fluid mosaic model of cell membranes,
A
the most common type of molecules in the membrane are proteins
B
basic membrane structure results from how the proteins interact with water
C
the membrane is a highly mobile mixture of phospholipids and proteins
D
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
A
look for a plasma membrane
B
see if a nucleus is present
C
check for the presence of DNA
D
. 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?
A
The cell came from a single-celled or multicelled organism
B
The cell has a nucleus or not
C
The cell has cytosol or not
D
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.
A
animals; plants and fungi
B
plants; animals and fungi
C
plants and fungi; animals
D
animals and plants; fungi
60
The highly folded membranes found in such eukaryotic organelles as mitochondria and chloroplasts
A
increase the surface area where key chemical processes can occur
B
help the cell against physical damage
C
make it possible to package large amounts of DNA within the cell
D
assist with cell movement
61
Which of the following statements about prokaryotes is false?
A
Prokaryotic cells concentrate important materials for the cells survival
B
The substance known as cytosol is found within the bacterial nucleus
C
Prokaryotic cells are much smaller than most eukaryotic cells
D
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?
A
They are components in the reactions of photosynthesis
B
They all participate in the degradation of large amounts of ATP
C
They all participate in the production of large amounts of ATP
D
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?
A
Lysosome
B
Vesicles
C
Mitochondria
D
Plasma membrane
64
Which of the following macromolecules are found in the plasma membrane?
A
Lipids and proteins only
B
Lipids, proteins, and carbohydrates
C
Proteins and carbohydrates only
D
Proteins only
65
Clearly defined nucleus, mitochondria in a large central vacuole and chloroplasts, indicate the group of organisms from
A
bacteria
B
fungi
C
plants
D
animals
66
Which of the following are responsible causing the diseases?
A
Pathogens
B
T cells
C
Lymphocytes
D
Macrophages
67
In which of the following cell types more cellular detail can be observed using an electron microscope compared to a light microscope?
A
Animal
B
Bacterial
C
Protist
D
All of these
68
Which of the following is present in both prokaryotes and eukaryotes?
A
Lysosome
B
Chloroplast
C
Plasma membrane
D
Vacuole
69
Hydrogen bonds in a-helices are
A
more numerous than Vander Waals interactions
B
not present at Phe residues
C
analogous to the steps in a spiral staircase
D
roughly parallel to the helix axis
70
The peptide bond in proteins is
A
only found between proline residues
B
usually cis unless proline is the next amino acid
C
usually trans unless proline is the next amino acid
D
is planar because of steric hinderance
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