WorksheetsMacromolecules - 2021 MCQs
Total questions: 79
Worksheet time: 40mins
Which of these is not a type of self-assembly?
Directed self-assembly, in which a template is used to assist the self-assembly process.
Post-modification, in which self-assembly involves the organization of several units prior to a final structure.
Strict, which is fully reversible and represents the global thermodynamic minimum.
Incommensurate, in which the product leads to a structural evolution which is dynamic.
Stereoisomers that are nonsuperimposable mirror images of each other are known as:
cis-trans isomers.
diastereoisomers.
enantiomers.
anomers.
In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces?
CH₄
CO₂
C₆H₁₃NH₂
CH₃OH
What types of intermolecular forces exist between HI and H₂S?
Dipole-dipole and ion-dipole
Dispersion forces, dipole-dipole, and ion-dipole
Dispersion forces and dipole-dipole
Dispersion forces only
The image below represents two polar molecules with permanent dipole moments. Which orientation represents the lowest energy state?
1
2
3
Both 2 and 3
Based on the molecular mass and dipole moment of the five compounds in the table below, which should have the highest boiling point?
CH₃CH₂CH₃
CH₃OCH₃
CH₃Cl
CH₃CN
What term best describes the nature of the interaction between the two molecules in the co-crystal shown in the figure below? The interaction is shown by the dashed lines.
Ion-dipole interaction
Halogen bond
Anion π interaction
Hydrogen bond
What type of information can be obtained from a Scanning Electron Microscope (SEM) that is not easily accessible from a Transmission Electron Microscope (TEM)?
Atomic-level resolution of internal structures
Chemical composition of individual atoms
Surface topography and texture of the sample
Electron diffraction patterns of crystallized materials
A true statement about hydrophobic interactions is that they:
are the driving force in the formation of micelles of amphipathic compounds in water.
do not contribute to the structure of water-soluble proteins.
have bonding energies of approximately 20–40 kJoule per mole.
involve the ability of water to denature proteins.
Which statement is INCORRECT?
Nanoscale materials have structural features (e.g. particle size or grain size) of at least one dimension in the range of 1–100 nm.
The top-down approach synthesises nanomaterials from atomic molecular species via chemical reactions or self-assembly of molecular constituents.
At the nanoscale, unique optical, magnetic, electrical, and other properties emerge.
Allotropes of carbon include graphene, nanotubes, fullerene, diamond, and graphite.
Which of the processes A–D will lead to a positive change in the entropy of the system? If all of these processes lead to a positive change in the entropy of the system, select D.
Sodium chloride crystals form as saltwater evaporates.
Helium gas escapes from the hole in a balloon.
Water freezes in a freezer.
All of these lead to a positive change in entropy of the system, as they are all spontaneous.
Suppose a chemical reaction is found to be spontaneous, but with ΔSsystem < 0. Which of the following statements must be TRUE?
ΔSsurroundings < 0 and its magnitude is < ΔSsystem. In other words, the system loses entropy and the surroundings also lose entropy. The loss by the surroundings is less than the loss by the system.
ΔSsurroundings < 0 and its magnitude is > ΔSsystem. In other words, the system loses entropy and the surroundings also lose entropy. The loss by the surroundings is greater than the loss by the system.
ΔSsurroundings > 0 and its magnitude is < ΔSsystem. In other words, the system loses entropy but the surroundings gain entropy. The gain by the surroundings is less than the loss by the system.
ΔSsurroundings > 0 and its magnitude is > ΔSsystem. In other words, the system loses entropy but the surroundings gain entropy, and the gain by the surroundings outweighs the loss by the system.
Which interaction between an electron beam and a solid sample can be used to collect information about the sample, and what information does it provide?
Elastic scattering provides information about the chemical composition of the sample.
Inelastic scattering provides information about the surface structure of the sample.
Backscattered electrons can provide information about the atomic number contrast in the sample.
X-ray emission provides information about the electrical conductivity of the sample.
Indicate which one of the following reactions results in a negative ΔSsystem.
H2O(g) ⇌ H2O(s)
CaCO3(s) ⇌ CaO(s) + CO2(g)
CuSO4(H2O)5 (s) ⇌ CuSO4(s) + 5H2O(g)
14O2(g) + 3NH4NO3(s) + C10H22(l) ⇌ 3N2(g) + 17H2O(g) + 10CO2(g)
The bomb calorimeter is used for the precise determination of the heat change accompanying a reaction. A bomb calorimeter operates at:
constant volume and constant pressure.
constant temperature.
constant volume.
constant pressure.
Which of the following scenarios violates the first law of thermodynamics – “the conservation of energy”?
A spring that extends and retracts forever, alternating between potential and kinetic energy.
An isolated electrochemical cell that indefinitely generates an electrical current.
An efficient wind turbine that converts all its energy from mechanical movement into electrical potential energy.
A machine that converts heat energy into work energy.
A reaction is spontaneous at 500 K. The enthalpy change for the reaction is +20,000 J (20 kJ). What can you conclude about the sign and magnitude of ΔS for the reaction? Helpful equation: ΔGsystem = ΔHsystem − T ΔSsystem
ΔS is < 40 J/K
ΔS is = 0.04 J/K
ΔS is = 40 J/K
ΔS is > 40 J/K
What is the most important property of phospholipids that allows interaction with the aqueous phase in lipid bilayers?
the chain length of the fatty acid
their hydrophobicity
their hydrophilic head group
their amphipathic structure
Adenine (A) and thymine (T) can base-pair through hydrogen bonding as shown in the figure below (the .......... represent hydrogen bonds). Which one of the following statements is CORRECT for the atoms involved in the hydrogen bonding?
The nitrogen atom in the ring of adenine has four non-bonding electrons involved in the hydrogen bond
The oxygen atom (on thymine) involved in the hydrogen bonding is electron deficient
The hydrogen atom of the N-H portion of thymine is electron deficient
The nitrogen of the amine (NH₂) group on adenine is electropositive
Of the 20 standard amino acids, only ____________ is not optically active. The reason is that its side chain ____________.
glycine; is a hydrogen atom
alanine; is a methyl group
serine; contains a hydroxyl group
valine; has a branched chain
When a solid interacts with an electron beam, what type of interactions can occur between the electron beam and the sample?
Elastic scattering, absorption, and refraction
Elastic scattering, inelastic scattering, and diffraction
Polarization, reflection, and emission
Refraction, ionization, and crystallization
The structure below represents an amino acid at:
a pH above the pI of the amino acid.
a pH below the pI of the amino acid.
at a pH equal to the pI of the amino acid.
at a pH that is half the pI of the amino acid.
The pKa values for all three ionisable groups of the amino acid lysine are shown in the figure below. Using this information, the pI value for lysine would be closest to_____:
11.0
7.22
8.95
9.74
An amino acid whose ‘R’ group is predominantly hydrocarbon would be classified as
non-polar
acidic
basic
polar
Which of the following statements about aromatic amino acids is correct?
The presence of a ring structure in its R group determines whether or not an amino acid is aromatic.
Histidine’s ring structure results in its being categorized as aromatic or basic, depending on pH.
On a molar basis, tryptophan absorbs more ultraviolet light than tyrosine.
The major contribution to the characteristic absorption of light at 280 nm by proteins is the phenylalanine R group.
Which pair of amino acids can have ionic interactions?
glutamic acid and serine
leucine and alanine
glutamate and lysine
glycine and asparagine
For amino acids with neutral R groups, at any pH below the pI of the amino acid, the population of amino acids in solution will have:
a net negative charge.
a net positive charge.
no charged groups.
no net charge.
The formation of a peptide bond between two amino acids is an example of a(n) __________ reaction.
Condensation
Hydrolysis
Oxidation
Reduction
A growth modulating peptide found in human plasma is shown below. Which of the following single letter codes represents the structure of this peptide?
GHK
KHG
GYK
KYG
By adding SDS (sodium dodecyl sulfate) during the electrophoresis of globular proteins, it is possible to:
determine a protein’s isoelectric point.
determine the amino acid composition of the protein.
preserve a protein’s native structure and biological activity.
separate proteins exclusively on the basis of molecular weight.
Identify which of the following terms refers to the arrangement of different protein subunits in a multiprotein complex.
primary structure
secondary structure
tertiary structure
quaternary structure
What are the differences between Elastic and Inelastic Scattering?
Elastic scattering occurs without any energy transfer, while inelastic scattering involves energy loss or gain.
Inelastic scattering preserves the direction of the scattered particles, while elastic scattering changes the direction.
Elastic scattering involves changes in the internal energy of the particles, while inelastic scattering does not.
Inelastic scattering only occurs in solids, whereas elastic scattering happens in gases and liquids.
α-helix has
3.4 amino residues/turn
3.6 amino residues/turn
3.8 amino residues/turn
3.0 amino residues/turn
The type of bond that is most important in maintaining secondary structure of a protein is:
hydrogen bonding between R groups.
hydrophobic interactions.
hydrogen bonding within the backbone.
salt bridges.
Which of the following does not stabilise the tertiary structure of a protein?
the hydrogen bonds
the hydrophobic effect
the amide bonds
the electrostatic interactions
For the unfolding reaction of ‘Protein X’, ΔH° = 210.6 kJ/mol. This means that:
unfolding is favored enthalpically.
folding is favored enthalpically.
the entropy is positive at all temperatures.
the entropy is negative at all temperatures.
Which of the following forces is the most unfavourable for protein folding?
Conformational entropy
Hydrophobic Interactions
Van der Waals interactions
Hydrogen bonds
Which of the following characteristics is a common feature of protein glycosylation?
Cell-specific glycosylation
Protein-specific glycosylation
Micro-heterogeneity of glycoproteins
All of the above
Which of the following statements about glycoproteins is incorrect? Glycoproteins
are an integral part the glycocalyx covering all human cell surfaces.
are generated from glycogen deposits in the cytosol of all cells.
are generated intracellularly within the glycosylation machinery.
are generated by a complex series of glycosyltransferases and glycosidases.
Solvophobic effects strongly influence the thermodynamic properties of solutions and are one of the driving forces of self-assembly processes of supramolecular structures. What other key forces will stabilise the formation of self-assembly systems?
The shape and size of the self-assembly molecules.
Non-covalent weak electrostatic interactions known as intermolecular forces.
The number of polar groups on the self-assembling molecular building blocks.
All of the above.
Cyclopropane, dimethyl ether, and acetonitrile have dipole moments of 0.0, 1.3 and 3.9 debye (D) units respectively. Arrange the solvents in order of their expected boiling point from highest to lowest.
cyclopropane, acetonitrile and dimethyl ether.
dimethyl ether, acetonitrile, and cyclopropane.
acetonitrile, dimethyl ether, and cyclopropane.
Dipole moments do not affect the boiling points of solvents.
Nucleotides consist of:
an acid bonded to a base bonded to a sugar.
an acid bonded to a base bonded to a phosphate.
a base bonded to a sugar bonded to a phosphate.
a base bonded to a phosphate bonded to a sugar
Cholesteric liquid crystals are coloured because?
of the twist and rotation between layers of self-assembled molecules
of the large number of conjugate bonds in the molecule
of large spacing between molecular layers
of the number of benzene rings in the molecule
What is NOT a viable method to produce nanodiamonds
Top-down approaches such as detonation of explosives such as trinitrotoluene (TNT)
Top-up approach such as the self-assembly of dissolved sugars
Bottom-up approaches such as chemical vapor deposition (CVD) using methane
Top-down approach by milling of High-Pressure, High-Temperature (HPHT) microdiamond particles
In the synthesis of gold nanoparticles, which of the following reducing reagents will produce the smallest gold nanoparticles
Sodium citrate
Sodium borohydride
Ascorbic acid
Tannic acid
What is the typical resolution of a modern transmission electron microscope?
Around 0.1 nanometre, 100 picometres or 1 Ångstrom
Around 1 nanometre, 1000 picometres or 10 Ångstrom
Around 10 nanometre, 10 000 picometres or 100 Ångstrom
Around 0.01 nanometre, 20 picometres or 1000 Ångstrom
What limits the resolution of a Transmission Electron Microscope?
chromatic aberrations
spherical aberration
astigmatism
All of the above.
In a mixture of the four proteins listed below, which should elute second in size-exclusion (gel filtration) chromatography? (Mr is the relative molecular weight)
cytochrome c Mr = 13,000 dalton
immunoglobulin G Mr = 145,000 dalton
ribonuclease A Mr = 13,700 dalton
RNA polymerase Mr = 450,000 dalton
Select the correct statement about fluorescence spectroscopy of molecules in the UV-Visible region.
Emission usually occurs at energies that are greater than the energies of excitation.
Emission usually occurs at energies that are lower than the energies of excitation.
Emission usually occurs at energies that are equal to the energies of excitation.
None of the above is correct.
From the below techniques, what is the method that can determine the most precise arrangement of atoms?
electron microscopy.
light microscopy.
Ramachandran plots.
x-ray diffraction.
Which of the statements about circular dichroism (CD) is not accurate?
The CD signal arises from the addition of the absorption of the left-handed and right-handed circularly polarized light by the sample.
The intensity of absorption of the left-handed and right-handed circularly polarised light is not the same for all types of secondary structural elements in proteins.
Compared to NMR spectroscopy or X-ray crystallography, CD is a very low-resolution method to obtain information about a polypeptide’s structure.
Monitoring changes in the CD spectrum of a protein upon heating can tell us about the thermodynamics of the unfolding process of the protein.
Haemoglobin exists in the body as a tetramer. Why is only the monomer form of haemoglobin observed during SDS-PAGE electrophoresis?
SDS-PAGE electrophoresis reduces disulfide bonds, preventing tetramer formation.
The tetramer is too large to enter the polyacrylamide gel matrix, and only the monomers can migrate.
The SDS detergent binds to the haemoglobin, causing it to unfold and separate into individual subunits.
SDS stabilizes the tertiary structure of haemoglobin, allowing it to remain as a monomer in the gel.
Collection, analysis and processing of x-ray diffraction data from a protein crystal yields a(n) ____________; analysis of 2D NMR data of a protein in solution yields a(n) ____________.
electron density map; count of hydrogen atoms in the molecule
electron density map; 3D structure of the protein
3D model; electron density map
2D image; 3D model
Which of the following statements is INCORRECT for mass spectrometry?
Mass spectrometry is used to identify unknown compounds within a sample, and to elucidate the structure and chemical properties of different molecules.
Particle are characterised by their mass to charge ratios (m/z) and relative abundances.
This technique basically studies the effect of ionizing energy on molecules.
This technique can be used on all state of matter.
What is meant by the 'phase problem' in X-ray crystallography?
The sample must be in the crystalline solid phase.
The phase of an X-ray wave changes when it is scattered by an atom.
The relative phases of diffracted X-ray beams are lost when the diffraction pattern is recorded.
Non-centrosymmetric crystal structures always give centrosymmetric diffraction patterns.
Which of the following best describes a State Function?
A property that depends on the path taken to reach a specific value
A property that is independent of the path taken and depends only on the initial and final states
A function that describes the rate of a reaction
A function that is only applicable to ideal gases
Which of the following best describes Enthalpy?
A measure of the total energy of a thermodynamic system.
The amount of disorder in a system.
The energy required to start a chemical reaction.
The rate at which a chemical reaction occurs.
Which law of thermodynamics states that as the temperature of a system approaches absolute zero, the entropy of the system approaches a constant minimum?
First Law of Thermodynamics
Second Law of Thermodynamics
Third Law of Thermodynamics
Zeroth Law of Thermodynamics
What does the Polydispersity Index measure in a sample?
The uniformity of particle sizes
The average molecular weight
The viscosity of the solution
The color intensity of the sample
Which of the following best explains the terms Configuration and Conformation?
Configuration refers to the fixed arrangement of atoms in a molecule, while conformation refers to the different spatial arrangements of atoms that can be converted by rotation around single bonds.
Configuration and conformation both refer to the fixed arrangement of atoms in a molecule.
Configuration refers to the different spatial arrangements of atoms that can be converted by rotation around single bonds, while conformation refers to the fixed arrangement of atoms in a molecule.
Configuration and conformation are terms used to describe the electronic configuration of atoms.
Which of the following are key factors that contribute to the stability of a host-guest complex?
Hydrogen bonding
Van der Waals forces
Electrostatic interactions
Temperature
Does Fluoromethane CH₃F exhibit hydrogen bonding between its molecules?
Yes, because it contains a highly electronegative atom.
No, because it lacks a hydrogen atom bonded to a highly electronegative atom.
Yes, because it can form hydrogen bonds with water.
No, because it is a nonpolar molecule.
What kind of intermolecular attractive force is shown in A?
Hydrogen bonding
Dipole-dipole interactions
London dispersion forces
Ion-dipole interactions
What kind of intermolecular attractive force is shown in B?
Hydrogen bonding
Dipole-dipole interactions
London dispersion forces
Ion-dipole interactions
What kind of intermolecular attractive force is shown in C?
Hydrogen bonding
Dipole-dipole interactions
London dispersion forces
Ion-dipole interactions
What kind of intermolecular attractive force is shown in D?
Hydrogen bonding
Dipole-dipole interactions
London dispersion forces
Ion-dipole interactions
For a chemical reaction with ΔH = −35.4 kJ, is the reaction exothermic or endothermic?
Exothermic
Endothermic
Cannot be determined
Neither
For a chemical reaction with ΔS = −85.5 J/K, does the reaction lead to an increase or decrease in the disorder of the system?
Increase
Decrease
No change
Cannot be determined
Given a chemical reaction where ΔH = −35.4 kJ, ΔS = −85.5 J/K, and the temperature is 298 K, what is the value of ΔG for the reaction?
120.9 kJ
9.6 kJ
−9.6 kJ
-120.9
For a chemical reaction with ΔH = −35.4 kJ and ΔS = −85.5 J/K, is the reaction spontaneous at 298 K under standard conditions?
Yes
No
Cannot be determined
Only at high temperatures
What are two reasons why researchers seek to achieve a ‘nano’ form of a material?
To increase the surface area and enhance reactivity
To improve the material's color and texture
To reduce the cost of production
To make the material more environmentally friendly
Hemoglobin is found in the red blood cells and carries oxygen around the body. One molecule of haemoglobin can bind up to a total of how many oxygen molecules?
Two
Three
Four
Five
Surfactants are compounds that lower the surface tension between two liquids, between a gas and a liquid, or between a liquid and a solid. An important property of surfactants is their critical micellar concentration or cmc. What is the critical micellar concentration?
The concentration at which surfactant molecules start forming micelles
The concentration at which surfactant molecules completely dissolve
The concentration at which surfactant molecules precipitate
The concentration at which surfactant molecules evaporate
What happens to a surfactant when the concentration of the surfactant is above its ‘cmc’ (critical micellar concentration) value?
The surfactant forms micelles.
The surfactant precipitates out of solution.
The surfactant becomes inactive.
The surfactant decomposes.
What is the primary function of surfactants?
Increase the boiling point of a liquid
Lower the surface tension between two liquids, between a gas and a liquid, or between a liquid and a solid
Stabilize solid structures in solutions
Increase the viscosity of liquids
Why is the critical micellar concentration (CMC) an important property of surfactants?
It determines the boiling point of the surfactant solution and offers greater stability to the solution
It marks the point at which surfactants change from reducing surface tension to forming micelles
It indicates when the surfactant begins to degrade, resulting in oil and water separation
It determines the characteristics and shape of micelles in solution at a given moment without the need for TEM
How can the critical micellar concentration (CMC) of a surfactant be determined or controlled?
By measuring the decrease in viscosity
By measuring changes in surface tension
By calculating changes in pH
By altering the temperature of the solution
The number-average molar mass and the mass-average molar mass of a mixture of two polymers are given as 71 kgmol⁻¹ and 90 kgmol⁻¹. Calculate the polydispersity index for the polymer and comment on if the solution is more likely to be monodisperse or polydisperse.
1.27, Monodisperse
1.27, Polydisperse
0.79, Monodisperse
0.79, Polydisperse
The sedimentation coefficient (s) for a macromolecule suspension is relatively easy to measure in the laboratory and is calculated from the following equation: s = M(1 - v̅ρ) / Nₐf. What happens to the value of ‘s’ when the frictional coefficient of the macromolecule doubles, but the molecular weight remains constant?
s doubles
s is halved
s remains the same
s increases fourfold
