PRACTICE QUESTIONS Flashcards
1. A colonic biopsy specimen from a 72-year old man with diarrhoea was being examined microscopically. Which of the following is the Pathologist unlikely to see in the specimen? A. Endothelial cells B. Epithelial cells C. Osteoblasts D. Ganglion cells E. Smooth muscle cells
C
what is a form of programmed cell death?
apoptosis
what is an increased in the number of cells?
hyperplasia
what is an increase in organ dimensions with no change in cell numbers?
hypertrophy
what is an altered state of maturation?
dysplasia
Scientists in the department of Genetics at Ninewells Hospital are analysing transcripts within bone marrow cells from patients attending the Haematology department. Which of the following best describes the material the analysis is being performed on? Genomic DNA Amino acids Histones Protein RNA Mitochondrial DNA Chromosomes
RNA
Which of the following statements is true about events during human embryonic development?
A. Implantation is complete 5 days after fertilization.
B. The development of the heart begins in Week 10
C. Cranial folding forms the foregut
D. Lateral folding forms the umbilical cord
E. The size of the head, relative to the body increases with gestational age
C
A 20-year old male university student visits his general practitioner with a sore throat. A throat swab is sent for microbiological analysis and Streptococcus pyogenes (S. pyogenes) is identified. Which of the following statements is true about S. pyogenes?
A. It is rod shaped B. It is a Gram negative organism C. It is a type of protozoa D. It causes haemolysis in cultures E. It is usually penicillin resistant
D
what is tagging of microbes by antibodies
opsonisation
what is movement of a cell along a chemical gradient
chemotaxis
what is engulfing of a pathogen by a macrophage
phagocytosis
what is the functional inactivation of a lymphocyte following antigen encounter
anergy
what is a change in the type of antibody produced
class switch
what is production of plasma cells from B lymphocytes
differentiation
Which of the following statements is incorrect about animal cell membranes?
A. The phospholipid head is hydrophilic.
B. The phospholipids tail is hydrophobic.
C. The cell wall outside the membrane offers protection.
D. Cholesterol contributes to the stability of the membrane.
E. Integral proteins are embedded in the lipid bilayer.
F. Carbohydrate chains are often bound to membrane protein.
C
what is a drug that binds to a receptor to mediate an effect by the activation of that receptor.
agonist
what is the mechanism of action of a drug
pharmacodynamics
what is the absorption, distribution, metabolism and excretion of a drug, or its metabolite.
pharmacokinetics
what is the strength of association between a receptor and ligand
affinity
what is the dose, or concentration, of drug needed to produce a given effect.
potency
Phosphoglucomutase catalyses the conversion of Glucose-6-phosphate to Glucose-1-phosphate. Which of the following statements is true about this reaction?
- Glucose-6-phosphate is a substrate
- The forward reaction results in glycogen breakdown
- Glucose-6-phosphate is an enzyme
- This is an exergonic reaction
1
Which of the following are close anatomical relations of the left kidney?
A. Tail of pancreas B. 2nd part of duodenum C. Ascending colon D. Descending colon E. Spleen F. Left adrenal gland
A
D
E
F
Which of the following statements about imaging are correct?
A. CT involves high dose ionising radiation.
B. There are no absolute contraindications to MRI.
C. There are no absolute contraindications to ultrasound.
D. Modern CT scan images can be viewed without loss of quality in all anatomical planes.
E. A plain radiograph of the abdomen is a good way to assess for free intra peritoneal gas.
F. Iodine based contrast is routinely used in contrast enhanced MRI.
A
C
D
A chemical change for which the associated enthalpy change is positive:
a) cannot occur spontaneously
b) may occur spontaneously if coupled to a reaction in which the enthalpy change is negative and of greater magnitude
c) raises the temperature of the surroundings
d) will inevitably occur spontaneously
B
a chemical reaction for which the associated free energy change is large and negative:
a) cannot occur spontaneously
b) is likely to be irreversible in the cell
c) will inevitably occur spontaneously
d) will occur very rapidly
B
which one of the following statements about ATP is correct?
a) atp can diffuse through cell membranes
b) atp is considered a low energy phosphate compound
c) atp is present at high concentrations in the cell
d) hydrolysis of atp is a strong exergonic reaction
C
which of the following statements best describes how a reaction is likely to behave if it has a large, negative value for G?
a) the reaction will be at equilibrium
b) the reaction is likely to happen to a small extent, with only a small amount of product formed
c) the reaction will happen to a moderate extent, with about as much product being formed as reactant being left
d) the reaction is likely to happen to a large extent, with large amounts of product formed
D - enthalpy change is large and negative, equilibrium lies to the right suggesting spontaneous reaction that favours the formation of products
At Keq the value of the change in free energy for a chemical reaction is:
a) zero
b) greater or less than zero but remains at a stable value
c) does not change with respect to energy transfer from coupled reactions
d) The point at which the concentration of reactants and products are equal.
A - DG Keq is the equilibrium constant, determined from ([C].[D])/[A].[B]). It represents the concentrations of products:reactants at which there is no net free energy transfer.
What is a polar molecule?
a) a molecule with no charge
b) a molecule with opposite charges at opposite ends
c) a molecule with identical charges at opposite ends
d) molecule with an unequal number of protons and electrons
B
How do water molecules arrange around ions?
a) the more negative atoms attach to positive ions
b) the more positive atoms attach to negative ions
c) water forms a hydration shell
d) all of these answers are true
D
Which is TRUE regarding the structure of hydrogen bonds?
a) Hydrogen bonds can only arise from the covalent interaction between oxygen and hydrogen atoms.
b) It is only the hydrogen atoms of a water molecule which interact with polar molecules
c) Hydrogen bonds involve a linear arrangement of one hydrogen atom between two electronegative atoms
d) Hydrogen bonds are angled at 104.3o
C
Which one of the following statements about amino acids is correct?
a) Amino acids are classified according to the structures and properties of their side chains.
b) Amino acids are uncharged at neutral pH.
c) Amino acids in proteins are mainly in the D-configuration.
d) Twenty four amino acids are commonly used in protein synthesis.
A
All amino acids contain an alpha carbon bonded to the following structures:
a) an amino group (-NH2), a carboxyl group (-COOH), a hydrogen (-H), a side chain (-R)
b) an amide group (-CONH2), a carboxyl group (-COOH), a hydrogen (-H), a side chain (-R)
c) an amino group (-NH2), a carboxyl group (-COOH), a hydroxyl group (-OH), a side chain (-R)
d) an amide group (-CONH2), a hydrogen (-H), a side chain (-R)
A
Which of the following statements is true about a peptide bond (RCONHR’)?
a) It is non planar.
b) It is capable of forming a hydrogen bond.
c) Electron resonance between amino and carbonyl groups creates a partial double bond
d) The cis configuration is favoured over the trans configuration.
C
During the formation of the peptide bond which of the following takes place?
a) The α-amino group of one amino acid acts as a nucleophile to displace the hydroxyl group of another amino acid forming a peptide bond.
b) Hydrogen atom is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
c) Hydroxyl group is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
d) Hydrogen atom is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
A
Compare solution A with pH = 4 to solution B with pH = 6.
A)The concentration of [H+] in solution A is twice that in solution B.
B)Solution A has greater buffering capacity than solution B.
C)The concentration of [H+] in solution A is 100 times that in solution B.
D)The hydroxide concentrations are equal in the two solutions since pH only measures the concentration of H+.
C - Log scale…. 0.0001 / 0.000001 = 100
Two weak acids, A and B, have pKa values of 4 and 6, respectively. Which statement is true?
A)Acid A dissociates to a greater extent in water than acid B.
B)For solutions of equal concentration, acid B will have a lower pH.
C)B is the conjugate base of A.
D)Acid A contains more ionizing groups than acid B.
The equivalence point of acid A is higher than that of acid B
A - Strong acids favour [H+].[A-] so ratio to [HA] gives a larger value. Since pKa = -logKa, pKa values become smaller with increasing acid strength
A strong acid will display a larger Ka but smaller pKa value compared to a weak acid. True or false?
a) True
b) False
A - Strong acids favour [H+].[A-] so ratio to [HA] gives a larger value. Since pKa = -logKa, pKa values become smaller with increasing acid strength
An Amino acid can act as an acid or a base?
a) True
b) False
A - The carboxyl group donates [H+] = acid
The amino group can accept [H+] and so can act as a base.
Which 3 statements about zwitterionic amino acids are correct?
a) Reducable atoms in the amino acid side group side group enable zwitterions to alter charge depending upon prevailing pH
b) Zwitterions are dipolar molecules which act as buffers of acids and bases.
c) Charge differences at amino and carboxyl residues of zwitterions balance each other such that the molecule is non-polar.
d) Zwitterion ion charge may be positive or negative depending upon prevailing pH.
e) Zwitterions display a single pKa
f) The overall charge of a zwitterion is neutral at a pH equivalent to the isoelectric point, pI.
B D F
Which type of bonding is responsible for the secondary
structure of proteins?
a) Disulphide bridges between cysteine residues.
b) Hydrogen bonding between the C=O and N-H groups of peptide bonds.
c) Peptide bonds between amino acids.
d) Salt bridges between charged side chains of amino acids.
B
Which term below best defines the ‘quaternary structure’ of a protein?
a) The arrangement of two or more polypeptide subunits into a single functional complex
b) The folding of the polypeptide backbone in three-dimensional space.
c) The interaction of amino acid side chains.
d) The sequence of amino acids in a polypeptide chain.
A
Which of the following statements about collagen is correct?
a) Collagen contains a high proportion of hydroxylated proline residues.
b) Collagen is a globular, intracellular protein.
c) Post-translational modification of collagen involves vitamin A.
d) The structure of collagen consists of a superhelix of three α helices twisted together.
A
Which of the following amino acids is mostly likely to disrupt an alpha helix?
a) Proline.
b) Leucine.
c) Glycine.
d) Valine.
A
Which of the following most accurately describes how secondary structures in proteins are stabilised?
a) Through ionic bonds operating between oppositely charged amino acid side chains.
b) Through covalent bonds joining different parts of the peptide backbone.
c) Through hydrogen bonds between different amino acid side chains.
d) Through hydrogen bonds joining different parts of the peptide backbone.
D
Which of the following pairs of amino acids might contribute to protein conformation by forming electrostatic interactions?
a) Glycine and leucine.
b) Glutamate and lysine.
c) Phenylalanine and tyrosine.
d) Lysine and arginine.
B
Which amino acid can form disulphide bonds?
a) Glycine.
b) Proline.
c) Glutamate.
d) Cysteine.
D
Which of the following best describes a protein domain?
a) The α-helical portion of a protein.
b) A discrete region of polypeptide chain that has folded into a self-contained three-dimensional structure.
c) The β-pleated sheet portion of a protein.
d) A feature that rarely occurs in globular proteins.
B
Which of the following statements correctly describes the effect of glutamic acid to valine substitution upon the quaternary structure of hemoglobin?
a) The heme domain is acidified causing iron to move from its normal Fe(II) to Fe (III)
b) Hydrophobic interactions between hemoglobin tetramers cause aggregation.
c) charge differences result in a and b subunit disaggregation
d) Electron transfer between a and b subunits and the heme domain no longer occurs.
B
Which of the following is not a component of DNA?
- Adenine
- Thymine
- Phosphate
- Ribose
4
which is true about nucleic acids?
- New nucleotides are added to the 5’ end of growing nucleic acids
- New nucleotides are added to the 3’ end of growing nucleic acids
- New nucleosides are added to the 3’ end of growing nucleic acids
2
which is false about dna replication?
- Replication is semi-conservative
- Replication is catalysed by DNA polymerases
- Replication is discontinuous
- Replication does not require RNA molecules
4
which is false about specific transcription factors?
- They contain one of several DNA binding domains
- They bind DNA at specific regulatory sequences
- They require additional factors to bind DNA
- They regulate transcription of several genes simultaneously
3
what are introns?
- Non-coding sequences
- Coding sequences
- Present in mRNA
- Binding sites for transcription factors
1
which is false about splicing?
- It occurs in the cytoplasm
- It occurs in the nucleus
- It removes introns from the transcript, leaving only exons
- It requires a complex machinery
1
which is true about translation in eukaryotic cells?
- It only requires energy for elongation
- It only requires special protein factors for termination
- Proteins are synthesised from the N-terminus to the C-terminus
- Translation can occur while transcription is still ongoing
3
translation in eukaryotic cells..
1.Can start at several different start codons
2.Starts with the first start codon from the 5’ end of the RNA
3.Proceeds from the 3’ end to the 5’ end of the mRNA
Occurs in the nucleus
2
which is false about the genetic code?
- It is nearly universal
- It is ambiguous
- It is degenerate
- It is based on triplets of nucleotides
2
which is not a type of mutation?
- Inversion
- Nonsense
- Translation
- Missense
- Deletion
- Point
3
nonsense mutations…
- Introduce a wrong amino acid
- Introduce a stop codon
- Remove one or two base pairs
- Have no negative consequence
2
which is true about buffers?
- Weak acids are not good buffers
- A buffer is a solution to control the pH of a reaction mixture
- A buffer is a solution which does not change its pH
2
which is false about the henderson hasselbach equation?
- It connects the acid dissociation constant of a weak acid to the pH of a solution containing this acid
- It allows us to calculate the pH of a solution containing a weak acid
- It allows us to estimate at which pH a weak acid is a good buffer
- It shows that the pH of a solution containing a weak acid is directly proportional to the concentration of the acid
4
which is false about amino acids?
- All amino acids have an alpha carbon, a carboxyl group, and an amino group
- All amino acids have D- and L-isomers
- Polar amino acids are soluble in water
2
which is false about the acid base properties of amino acids?
- The zwitterion form has both positive and negative charges
- In solutions of low pH amino acids are positively charged
- In solutions of high pH amino acids are positively charged
- The side groups of amino acids can contain titratable groups
3
which of the following interactions isnt involved in stabilising the 3D structure of a protein? 1.Hydrophobic interactions 2.Electrostatic interactions 3.Covalent interactions 4.Hydrogen bonds None of them
4
In which of the scenarios listed should hand hygiene be achieved with anti-microbial soap and water rather than alcohol rub hand gel?
A: After taking history from a patient
B: Aiding patient to mobilize from bed to chair
C: Bringing a commode to patient’s bedside
D: Prior to inserting intravenous cannula
E: Auscultation of patient’s chest
D
What can you deduce from this information?
Hexokinase I in red blood cells and Glucokinase in liver and pancreas both catalyze the phosphorylation of glucose to glucose-6-phosphate. Hexokinase I has a Km for glucose of 0.05 mM, while Glucokinase has a Km for the same substrate of 5-6 mM.
A: Both enzymes are almost fully saturated at normal fasting blood glucose levels
B: Hexokinase I is regulated by allosteric interactions,
C: Hexokinase I has a higher affinity for glucose than Glucokinase.
D: Glucokinase can convert glucose to glucose-6-phosphate at a higher rate than Hexokinase I.
E: Glucokinase is inhibited by a competitive inhibitor
C
what is a change from one mature cell type to another known as?
metaplasia
the germ layers are formed during which stage of embryogenesis?
gastrulation
which enzyme transcribes genetic material?
RNA polymerase
a patient with this disease has trisomy 21
downs syndrome
this disease is acquired through co-dominant inheritance
sickle cell anaemia
a patient with this disease has 49 chromosomes
klienfelter syndrome
Which one of the below statements is TRUE?
A.
Apoptosis is always indicative of pathological disorder
B.
Hyperplasia is irreversible
C.
Hypertrophy is tissue enlargement due to an increase in the number of cells
D.
Hypoplasia is a developmental disorder
E.
Hyperplasia is always pathological and leads to cancer
D
what is an increase in cell number known as?
hyperplasia
what is the definition of alpha haemolysis?
partial haemolysis - green colour
Describe the appearance of neisseria meningitidis
A) anaerobic gram positive bacillus
B) aerobic gram positive cocci
C) anaerobic gram negative bacillus
D) aerobic gram negative cocci
E) anaerobic gram negative cocci
D
which of the following statements is correct?
A) Endotoxin is produced by gram negative organisms
B) Exotoxin is produced by gram negative organisms
C) Endotoxin is produced by gram positive organisms
D) Endotoxin can be produced by other gram positive and negative organisms
A
where does fertilisation normally occur?
ampulla of the uterine tube
which statement is true about staphylococci?
a They appear on gram film as negative cocci in chains
b Haemolysis is important in the classification of this genus
c These appear as Gram positive cocci in clusters on Gram stain
d These appear as Gram postive cocci in stripes on Gram stain
C
what is an increase in size of cells?
hypertrophy
what antibody is the most abundant in the blood?
IgG
what antibody exists as a dimer in breast milk, saliva and tears?
IgA
what antibody is found in the blood as a pentameric molecule?
IgM
what is the normal site of fertilisation?
ampulla
what is the definition of Km?
exactly half of the maximum velocity
what part of the hand is most commonly missed during routine handwashing?
thumb
what is the enzyme that transcribes genetic material?
RNA polymerase
