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Question 1
2 out of 2 points
Which of the following statements complete the sentence below correctly?
After decolorization (alcohol/acetone wash) step of Gram staining, Gram negative
bacteria are visible under microscope .....................
Selected Answer:
Answers:
after safranine counterstaining.
after safranine counterstaining.
due to crystal violet staining.
with no further treatment.
after iodine treatment.
Response
Feedback:
Correct answer!
Gram negative bacteria are colorless after decolorization (alcohol/acetone
wash) step due to lipid solution of LPS layer and dehydration of
peptidoglycan. They cannot be visualized without further treatment under
a microscope. They are not purple stained due to crystal violet staining, as
cells are decolorized with alcohol decolorization step. Further iodine
treatment will not impart a color for visualization under a microscope. A
counterstain (safranine) is needed to visualize them.
Question 2
2 out of 2 points
What does a "monochromator" do in a spectrophotometer?
Selected
Answer: It breaks up the wavelengths in the light into individual wavelengths
Answers:
It is the first type of material measured using a spectrophotometer.
It breaks a material down into individual atoms.
It emits light.
It breaks up the wavelengths in the light into individual wavelengths
Response Correct response:
Feedback:
It breaks up the wavelengths in the light into individual wavelengths.
(The specific wavelength of light needed to measure the characteristic
absorption of a solution is provided by the chromator).
Incorrect answers
All other answers are incorrect.
Question 3
0 out of 2 points
In the laboratory equipped with a high-tech spectrophotometer, the enzyme catalase is
measured by its absorbance in the UV region (at 340 nm).
Which amino acids are responsible for this absorbance? (Choose as many as
required).
Selected Answers: Tyrosine (Tyr)
Asparagine (Asn)
Answers: Tryptophan (Trp)
Tyrosine (Tyr)
Proline (Pro)
Asparagine (Asn)
Phenylalanine (Phe)
Response Correct Responses:
Feedback:
Phenylalanine, Tyrosine and Tryptophan
(These amino acid have aromatic side chains allowing them to absorb at
UV).
Incorrect responses:
Proline: An imino acid
Answers:
The phase contrast and differential interference contrast microscopes are
used for the observation of living cells in cultures.
The primary magnification of a bright-field microscope is defined by the power
of the ocular lens.
Hematoxylin is an acidic dye which stains the nucleus to purple color.
Immunohistochemistry is the technique used to identify specific tissue
components by means of a specific antigen/antibody reaction tagged with a
visible label.
The lipid containing adipocytes look empty under the light microscope due to
the organic solvents used in routine histological technique.
Response Hematoxylin is a basic dye that stains the acidic DNA, RNA etc. in the
Feedback:
nucleus to purple color.
The primary magnification of a bright-field microscope is not defined by
the power of the ocular lens but is defined by the objective lens.
Question 6
1.33333 out of 2 points
Match the following features with related domains.
They can live in extreme conditions: [a]
First amino acid during protein synthesis is formylmethionine: [b]
They have linear chromosome, and also have histone proteins: [c]
They are sensitive to antibiotics: [d]
They have 70S ribosomes and produce methionine as the first amino acid during
protein synthesis: [e]
They have membrane-enclosed organelles: [f]
Selected Match the following features with related domains.
Answer:
They can live in extreme conditions: Archaea
First amino acid during protein synthesis is formylmethionine:
Archaea
They have linear chromosome, and also have histone proteins:
Eukarya
They are sensitive to antibiotics: Bacteria
They have 70S ribosomes and produce methionine as the first amino
acid during protein synthesis: Eukarya
They have membrane-enclosed organelles: Eukarya
Answers: Match the following features with related domains.
They can live in extreme conditions: Archaea
First amino acid during protein synthesis is formylmethionine:
Bacteria
They have linear chromosome, and also have histone proteins:
Eukarya
They are sensitive to antibiotics: Bacteria
They have 70S ribosomes and produce methionine as the first amino
acid during protein synthesis: Archaea
They have membrane-enclosed organelles: Eukarya
All Answer Choices
Eukarya
Archaea
Bacteria
Question 7
2 out of 2 points
In a laboratory, a scientist observes the following features under the microscope. Which
of these observations supports cell theory?
I. Skeletal muscle cells that contain more than one nucleus.
II. Mature platelets without nucleus.
III. Epithelial cells that undergo mitosis.
IV. Endocrine gland tissue samples that contain cells as their main building blocks
Selected Answer: III and IV
Answers: II only
I and III
II and IV
III and IV
Question 8
2 out of 2 points
What is the name of the lipid class presented below?
The concentration of HOCl decreases.
The concentration of HOCl remains the same.
Response Correct Response:
Feedback:
The concentration of HOCl increases (If we add
additional hypochlorite ions to this reaction, the equilibrium will shift to the
left, in order to produce more Hypochlorous acid .)
Incorrect Response:
The concentration of HOCl decreases (If we add
additional hypochlorite ions to this reaction, the equilibrium will shift to the
left, in order to produce more Hypochlorous acid .)
The concentration of HOCl remains the same (If we add
additional hypochlorite ions to this reaction, the equilibrium will shift to the
left, in order to produce more Hypochlorous acid .)
The concentration of H 3
O
increases (If we add
additional hypochlorite ions to this reaction, the equilibrium will shift to the
left, in order to produce more Hypochlorous acid. So the hydronium ions will
decrease. )
Question 10
2 out of 2 points
Regarding the properties of a non-polar molecule or group, which of the followings are
correct? (Choose as many as required).
Selected Electrons are shared equally by the atoms.
Answers:
Non-polar molecules dissolve better in non-polar solvents.
CO
is a non-polar molecule.
Answers:
There is a large electronegativity difference between two atoms in the
bond.
One atom is more likely to donate its electrons to another atom in the
bond.
Electrons are shared equally by the atoms.
Non-polar molecules dissolve better in non-polar solvents.
CO
is a non-polar molecule.
Response Correct Responses
Feedback:
Electrons are shared equally by the atoms. (In non- polar molecules, they
form covalent bonds that atoms share the electrons equally, rather than fully
gaining or losing them.)
Non-polar molecules dissolve better in non-polar solvents. (Molecular
polarity affects solubility in that polar molecules are best solvated by polar
solvent molecules and nonpolar molecules are best solvated by nonpolar
solvent molecules )
CO
is a non-polar molecule. ( CO 2
is a linear molecule and the Oxygen (O)
atoms on each end are symmetrical. Polarity results from an unequal
sharing of valence electrons. Because of this symmetry there is no region of
unequal sharing and CO 2
is a nonpolar molecule.)
Incorrect responses
There is a large electronegativity difference between two atoms in the bond.
( No electronegativity difference between two atoms leads to a pure non-
polar covalent bond. A small electronegativity difference leads to a polar
covalent bond. A large electronegativity difference leads to an ionic bond)
One atom is more likely to donate its electrons to another atom in the bond.
(Ionic bonding is the complete transfer of valence electron(s) between
atoms.)
Question 11
2 out of 2 points
The melting point of fatty acids depends upon which parameter?
Selected Answer: Degree of unsaturation
Answers: Charge on the carbon
Position of the double bond
Degree of unsaturation
Shape of the fatty acid
Response Correct answer:
Feedback:
Degree of unsaturation.
Degree of unsaturation is defined for the fatty acids by the number of
double bonds in their hydrocarbon chain. Degree of
unsaturation increases with the number of double bonds which lowers the
melting point of the fatty acids due to formation of kink structures in their
hydrocarbon chain.
Incorrect answer:
Shape of the fatty acid
Position of the double bond
Charge on the carbon
These parameters do not affect the melting point of fatty acids because
they are not related to degree of unsaturation (the number of double
bonds) in fatty acids.
Question 12
2 out of 2 points
carbon dioxide and water.
Dehydration reactions link monomers together into polymers by releasing
water.
Question 14
2 out of 2 points
Alcohol dehydrogenase (ADH) is an enzyme requiring oxidized nicotinamide adenine
dinucleotide (NAD
) for catalytic activity. In the reaction catalyzed by ADH, an alcohol is
oxidized to an aldehyde as NAD
is reduced to NADH and dissociates from the
enzyme.
What is the main function of NAD
in this reaction?
Selected Answer: Coenzyme
Answers: Heterotropic effector
Coenzyme
Prosthetic group
Apoenzyme
Cofactor
Response Correct Response:
Feedback:
Coenzyme (NAD - NADH) is coenzyme for oxydoreduction reactions.
Incorrect responses:
Apoenzyme (protein part of an enzyme)
Prosthetic group: This is a small molecule strongly bound to the enzyme;
however, NAD+ leaves the enzyme following the reaction
Cofactor: It is a metal
Heterotropic effector: It is a molecule which either activates or inhibits an
allosteric enzyme. Heterotropic effectors are not coenzymes.
Question 15
2 out of 2 points
The active site of an enzyme will bind to which of the following molecules? (Choose as
many as required)
Selected Answers: Substrate of the reaction
Competitive inhibitors
Answers: Substrate of the reaction
Allosteric inhibitors
Noncompetitive inhibitors
Competitive inhibitors
Response Correct responses:
Feedback:
Substrate (Substrate binds to the active site)
Competitive inhibitor (Having a structure similar to the substrate, it also
binds to the active site)
Incorrect responses:
Allosteric inhibitors (They bind to a site other than the active site)
Noncompetitive inhibitors (As they do not have a structure similar to the
substrate, they bind to another site on the enzyme)
Question 16
2 out of 2 points
In comparing the alpha-helix to the beta-sheet, which statement is correct only for the
beta-sheet?
Selected It is stabilized by interchain hydrogen bonds.
Answer:
Answers: It is stabilized by interchain hydrogen bonds.
Extensive hydrogen bonds between the carbonyl oxygen (C=O) and the
amide hydrogen (N-H) of the peptide bond are formed.
It is an example of secondary protein structure.
It may be found in typical globular proteins.
Response Correct answer:
Feedback:
It is stabilized by interchain hydrogen bonds. (This is associated only with
the beta-sheet).
Incorrect answers: All others (All others are associated with BOTH alpha
helix and beta sheet).
Explanation: The beta-sheet is stabilized by interchain hydrogen bonds
found between separate polypeptide chains and by intrachain hydrogen
bonds formed between regions of a single polypeptide.
The alpha helix, however, is stabilized only by intrachain hydrogen bonds.
The incorrect statements are true for both of these secondary structural
elements.
Question 17
0 out of 2 points
Lysine is an amino acid having the following acid dissociation constants (pKa):
pK1= 2.2 (Alpha carboxyl group)
(Asp is aspartate. The amino acid which contains a secondary amine
group is proline, which does not exist in this peptide. The
two cysteine residues can, under oxidizing conditions, from
a disulfide (covalent) bond. The peptide is a heptapeptide (contains 7
amino acid residues).
Question 19
2 out of 2 points
Which of the following statements concerning "hemoglobin" are correct? (Choose as
many as required)
Selected Answers: Hemoglobin is an allosteric protein.
Hemoglobin has four subunits, two alpha and two beta.
One hemoglobin molecule contains 4 hemes.
Answers: Hemoglobin is an allosteric protein.
Hemoglobin stores oxygen in tissues.
Hemoglobin has four subunits, two alpha and two beta.
The highest structure level of hemoglobin is tertiary.
One hemoglobin molecule contains 4 hemes.
Response Correct responses:
Feedback:
Hemoglobin has four subunits, two alpha and two
beta (Hemoglobin has two alpha and two beta chains, thus four
subunits).
One hemoglobin molecule contains four hemes (Each subunit of
Hemoglobin contains one heme).
Hemoglobin is allosteric (having quarternary structure,
hemoglobin is allosteric- subunits cooperate in binding oxygen).
Incorrect responses:
The highest structure level of Hemoglobin is tertiary (No, it is
quarternary).
Hemoglobin stores oxygen in tissues (No, hemoglobin carries
oxygen in the blood to liberate to the tissues).
Question 20
2 out of 2 points
A 28-year-old female presents with fluctuating fatigue, drooping of her eyelids, difficulty
swallowing and slurred speech (myastenia gravis). The patient is given a drug
(pyridostigmine) that affects the enzyme acetylcholinesterase's activity. Acetycholinest
arase-catalyzed reaction was analyzed kinetically in the presence and absence of the
drug, and the following results are obtained:
Effect on Km (as compared to No drug): Apparently increased
V max: not changed (as compared to No drug)
The drug exerts its effect by what kind of mechanism?
Selected Answer: Competitive inhibition
Answers: Non-competitive inhibition
Competitive inhibition
Irreversible inhibition
Activation of the enzyme
Response Correct response:
Feedback:
Competitive inhibition (The Km is apparently increased and the Vm
unchanged)
Incorrect responses:
Activation of the enzyme: In such a case, Km is expected to increase
(as in allosteric activation).
Noncompetitive inhibition: ( The Vmax is decreased and the Km not
changed)
Irreversible inhibition: (The enzyme is completly inactivated).
Question 21
2 out of 2 points
Which of the following statements regarding enzymes is correct?
Selected Enzymes increase the rate of a reaction.
Answer:
Answers: Enzymes catalyse only reversible reactions.
Enzymes prevent changes in substrate concentrations.
Enzymes increase the rate of a reaction.
Enzymes are permanently altered by the reactions they catalyze.
Enzymes increase the activation energy required for a chemical
reaction.
Response Correct answer:
Feedback:
Enzymes increase the rate of a chemical reaction.
Incorrect answers:
Enzymes increase the activation energy required for a chemical reaction.
(Enzymes decrease the activation energy required).
Enzymes catalyse only reversible reactions. (Enzymes can
catalyze reversible or irreversible reactions).
Enzymes are permanently altered by the reactions they catalyze (No,
enzymes do not themselves get altered and can be reused for many
reactions).
Enzymes prevent changes in substrate concentrations (No, as the
reaction proceeds, the substrate concentration is decreased).
Incorrect answers:
All others
(Oxydoreductase: One species is oxidized while another is
reduced
Isomerase: Isomerization takes place
Lyase: Breaking downand forming a double bond
Ligase: Joigning two species)
Question 24
2 out of 2 points
Dihydroxyacetone phosphate, shown below, is an intermediate compound of glycolysis.
What kind of functional groups are found in this molecule? (Choose the best choice.)
Selected Answer: Hydroxyl, carbonyl and phosphate groups
Answers: Sulfhydryl, hydroxyl and carboxyl groups
Amino, phosphate and hydroxyl groups
Carboxyl, hydroxyl and phosphate groups
Hydroxyl, carbonyl and phosphate groups
Response Correct response:
Feedback:
Hydroxyl, Carbonyl and phosphate groups ( Dihydroxyacetone phosphate
contains Hydroxyl (OH), Carbonyl (C=O) and phosphate groups (PO4))
Incorrect Response:
Carboxyl, hydroxyl and phosphate groups (Dihydroxyacetone phosphate
does not contain a carboxyl (COOH) group)
Sulfhydryl, hydroxyl and carboxyl groups (Dihydroxyacetone phosphate
does not contain a carboxyl (COOH) and a Sulfhydryl (SH) group)
Amino, phosphate and hydroxyl groups (Dihydroxyacetone phosphate
does not contain an amino (NH2) group)
Question 25
2 out of 2 points
A drug interfering with microtubule formation would cause a defect in which of the
following processes? (Choose as many as possible)
Selected Movement of sperm
Answers:
Axonal transport of secretory vesicles containing a neurotransmitter
Formation of cilia
Movement of chromosomes to the opposite poles during anaphase
Answers: Movement of sperm
Splitting of cells during cytokinesis
Axonal transport of secretory vesicles containing a neurotransmitter
Formation of cilia
Movement of chromosomes to the opposite poles during anaphase
Formation of lamellipodia and filopodia
Question 26
1.5 out of 2 points
Which of the following statements regarding the cytoskeletal elements are correct?
(Choose as many as required)
Selected
Answers: Intermediate filaments are not polar, therefore do not have motor
proteins.
The motor protein for actin filaments is myosin.
Actin filaments form through a process called treadmilling.
Answers:
Intermediate filaments are not polar, therefore do not have motor
proteins.
The motor protein for actin filaments is myosin.
The motor protein kinesin is responsible of anterograde movement.
Actin filaments form through a process called treadmilling.
Intermediate filaments form by polymerization.
Question 27
0 out of 2 points
Which of the following statement is matched incorrectly?
Selected Electroencephalography ----- records electrical activity of the brain
Selected Regression in health
Answer:
Answers:
Usage of artificial intelligence and machine learning in diagnostic tools
Transplantation of engineered organoids
Regression in health
Three-dimensional printing of drugs to overcome the drug costs
Smartphone-based diagnostic tools
Response Answer: Modern medicine and translational medicine are affording people
Feedback:
longer and healthier lives. Researchers want to take improvements in
health even further. With advances in gene editing, technology to
overcome paralysis and efforts to address high drug costs, the future of
medicine is bright. In this respect, 3D printing of drugs, transplantation of
engineered organoids, smartphone-based diagnostic tools, and usage of
artificial intelligence and machine learning in diagnostic tools are all
associated with the improvement in the future of medicine.
The answer is a) Regression in health.
Question 30
2 out of 2 points
You have constructed a protein named "importin" that cannot bind to the nuclear
localization signal (NLS).
What would you expect about the effect of this change on macromolecules that traffic
between the nucleus and the cytoplasm?
Selected
Answer: Such a change would prevent macromolecules to be imported into the
nucleus.
Answers:
Such a change would prevent macromolecules to be imported into the
nucleus.
Such a change would reduce exportation of macromolecules out of the
nucleus.
Such a change would increase exportation of macromolecules out of
the nucleus.
Such a change would induce importation of macromolecules into the
nucleus.
Response Importin plays a role in transportation of macromolecules from cytoplasm
Feedback:
into the nucleus. The constructed importin protein would not be able to
import macromolecules into the nucleus since it will not bind to NLS.
Therefore, such a change would prevent macromolecules to be imported
into the nucleus.
Question 31
2 out of 2 points
Match the following functions with appropriate type of membrane proteins.
Allows a particular molecule or ion to cross the plasma membrane freely: [a]
Selectively interacts with a specific molecule or ion to cross the plasma membrane, and
this interaction triggers conformational change: [b]
Identifies the cells by the help of glucosyl residues: [c]
Shaped for specific ligand binding that triggers downstream cellular events: [d]
Catalyzes a specific reaction: [e]
Selected Match the following functions with appropriate type of membrane
Answer:
proteins.
Allows a particular molecule or ion to cross the plasma membrane
freely: Channel protein
Selectively interacts with a specific molecule or ion to cross the plasma
membrane, and this interaction triggers conformational change:
Carrier protein
Identifies the cells by the help of glucosyl residues: Cell
recognition protein
Shaped for specific ligand binding that triggers downstream cellular
events: Receptor protein
Catalyzes a specific reaction: Enzymatic protein
Answers: Match the following functions with appropriate type of membrane
proteins.
Allows a particular molecule or ion to cross the plasma membrane
freely: Channel protein
Selectively interacts with a specific molecule or ion to cross the plasma
membrane, and this interaction triggers conformational change:
Carrier protein
Identifies the cells by the help of glucosyl residues: Cell
recognition protein
Shaped for specific ligand binding that triggers downstream cellular
events: Receptor protein
Catalyzes a specific reaction: Enzymatic protein
All Answer Choices
